BACKGROUND: Many antimicrobial stewardship programmes (ASPs) target the intensive care unit owing to high antimicrobial utilisation. In this review, we summarise and assess the quality of evidence supporting the implementation of various ASP strategies in the intensive care unit setting with a focus on publications between 2010 and 2015.
METHODS: We searched Medline up to April 2015 and screened publications of interest for additional relevant articles. We grouped the strategies into four categories: audit and feedback, formulary restrictions, guidelines/clinical pathways, and procalcitonin. We used GRADE terminology to describe the quality of evidence.
RESULTS AND CONCLUSIONS: We identified several studies reporting optimisation and reduction of antibiotic utilisation as well as cost reduction in all four strategies. Randomised controlled trials reviewing the role of procalcitonin demonstrate a moderate level of evidence. Given the lack of randomised controlled trials to support the role of guidelines, formulary restrictions, and audit and feedback, the level of evidence supporting these strategies is low. Importantly, there is no convincing evidence to support the main goal of ASP, namely to improve patient outcomes. Larger, rigorous long-term studies using a cluster randomised controlled trial or at least a controlled quasi-experimental design with time series are required to assess the impact of ASP on patient-important outcomes and on the emergence of resistance in the intensive care unit setting.
Keywords: quality, review, ICU, intensive care, stewardship, summary, critical care, antimicrobial
For over 50 years, experts have noted extensive inappropriate or unnecessary use of antimicrobials in the range of 30–50% [1–6]. Inappropriate use of antimicrobials is typically defined as wrong indication, spectrum, route, dose or duration of therapy . The emergence of resistance as a consequence of antibiotic use [7, 8] (see http://www.anresis.ch for current resistance patterns in Switzerland) is associated with poor clinical outcomes and increased healthcare costs [9, 10]. In fact, emergence of resistance continues to pose a challenge as demonstrated by the global spread of New Delhi β-lactamase producing Enterobacteriaceae resulting in strains that are resistant to virtually all currently available antibiotics . Furthermore, despite worldwide efforts to promote development of new antibiotics, the pipeline remains dry . In addition, antibiotic exposure is a trigger for Clostridium difficile infections and outbreaks [2, 3, 13]. Antimicrobial stewardship programmes (ASPs) continue to be implemented in hospitals and communities around the world as quality improvement and patient safety programmes aimed at curbing inappropriate use of antibiotics with the ultimate goal of optimising patient outcomes while minimising its unintended consequences .
Given the high density of antibiotic utilisation in the intensive care unit (ICU) setting and the importance of appropriate choice, particularly in septic patients , many programmes focus on this setting, assuming the greatest return on investment. A systematic review published in 2011 summarised the evidence on ASP in ICUs published up to 2010 and concluded that although more rigorous studies were required, available evidence did suggest antimicrobial stewardship was associated with improved utilisation of antimicrobials in the ICU setting, improvement in resistance and fewer adverse events .
In this review, we summarise and assess the quality of evidence supporting the implementation of various stewardship strategies in the ICU setting with a focus on the time period from 2010–2015.
We searched Medline on April 1 2015 using the search terms “(critical care) AND stewardship” and “(intensive care) AND stewardship”. We identified 133 and 193 articles, respectively, and also screened review and systematic review articles for additional studies. In this review we summarise 28 of the most relevant articles. We grouped the studies into those assessing the use of audit and feedback, formulary restrictions, procalcitonin, and those with mixed interventions or guidelines and clinical pathways. We adapted the Grading of Recommendations Assessment, Development and Evaluation (GRADE)  terminology to assess the quality of evidence for each of the four ASP strategies. A systematic assessment of the risk of bias of each included study and a full GRADE assessment of the overall level of evidence was beyond the scope of this non-systematic review article.
|Table 1: Studies on prospective audit and feedback.|
|Author||Country||Year||Design||ASP model||Acceptance rate for interventions||Outcomes and results|
|Amer ||Saudi Arabia||2010–2011||Quasi-experimental|
|ICU/ID pharmacist and ICU/ID physician||96.3%||Appropriateness: higher|
|NA||Appropriateness around day 3: unchanged|
Abx utilisation: lower
Abx costs: lower
|Diaz Granados ||USA||2006–2009||Quasi-experimental|
|66.5%||Abx utilisation: lower|
Abx selection: improved
Abx duration: shorter
|ID physician and pharmacist||82%||Abx utilisation (broad-spectrum): lower|
Abx costs: lower
Resistance pattern: improved
|Ijo ||USA||2009–2010||Comparison to published literature||ICU pharmacists||NA||LOS: lower|
Abx cost: higher
|ID physician and pharmacist|
Daily ASP rounds
|NA||% sterile cultures treated: increased|
% nonsterile cultures treated: decreased
% appropriate documentation: improved
Abx utilisation: lower
Abx costs: lower
|ID physician and pharmacist|
Daily ASP rounds
|94%||Abx utilisation: lower|
Abx costs: lower
CDI rates: unchanged
|ID fellow and pharmacist||88%||Appropriateness: higher|
Abx utilisation: lower
Mortality: unchanged (ICU)
Mechanical ventilation days: reduced
|ID physician review of positive blood cultures||80.6%||Abx utilisation: lower|
Abx costs: lower
HAI rate: unchanged
ICU re-admission: unchanged
|Abx = antibiotics; ASP = antimicrobial stewardship programme; CDI = C. difficile infection; HAI = hospital-acquired infections; ICU = intensive care unit; ID = infectious diseases; LOS = length of stay|
Audit and feedback
Prospective audit with intervention and feedback is generally regarded as the gold standard stewardship intervention and received an A-1 grading in the Infectious Diseases Society of America (IDSA) guidelines . This was based on two randomised controlled trials [16, 17] and two observational studies [18, 19], none of which were conducted in the ICU setting.
We identified nine relevant studies utilising audit and feedback in an ICU environment (table 1). The highest quality study was an interrupted time-series with a control group conducted at a large tertiary care centre in Ontario, Canada, by Elligsen et al., and targeted ICU patients on broad-spectrum antibiotics with audit and feedback on day 3 and 10 of therapy over a 1 year period . The ASP pharmacist reviewed patients, conferred with the infectious diseases physician and provided feedback to the team. They reported a reduction in broad-spectrum antibiotic use with no changes in overall use or in their two controls, resulting in a 23% reduction in antimicrobial costs ($95 000). Also, Gram-negative susceptibility to meropenem improved over time in the ICUs. There was no impact on ICU length of stay (LOS) and mortality. The design of this study had the lowest risk of bias; however, the control groups were not optimal (broad-spectrum antibiotics in medical and surgical wards, stress ulcer prophylaxis in the ICU) and it was a single-centre study.
A second time-series analysis was published by Wang et al. from Taiwan . They assessed the impact of a blood culture-guided de-escalation of empirical antimicrobials as an add-on to an existing stewardship programme in their 16 adult ICUs. They extended their pre-existing computerised antimicrobial approval system by flagging patients with a positive blood culture for a second review within 48 hours. Antibiotic utilisation, primarily carbapenems, gentamicin and those with activity against vancomycin-resistant Enterococcus, showed a significant reduction. This was reflected by a 19% decrease in antimicrobial costs. However, patient outcomes remained unchanged. Notably, this was an extension of a robust pre-existing ASP, thus, the findings might not be generalisable to a setting where an ASP has not been established.
Finally, Bornard et al. published a time-series study from France . The intervention included thrice-weekly ASP rounds by an infectious diseases specialist combined with teaching sessions and daily contact with a microbiologist. They found a nonsignificant improvement in appropriate courses of antimicrobials during the intervention (80% vs 73% at baseline), with a higher rate of modification on days 2–4. This study was small (37 and 44 patients, respectively), and the lack of improvement might have been due to a ceiling effect that was attributed to a higher than expected baseline appropriateness of antibiotics.
We also identified five uncontrolled quasi-experimental studies [23–27]. Amer et al. from Saudi Arabia targeted five antibiotics and compared the appropriateness of empirical treatment in patients receiving these antibiotics before and after programme implementation . Appropriateness of treatment increased from 30.6% to 100%. Prior to the ASP review, 20.9% of patients were treated appropriately, but the acceptance rate for ASP recommendations was 96.3%. The intervention resulted in a 68% reduction in the targeted antibiotics from 1 177.8 to 376.2 defined daily doses / 1000 patient days (DDD/1 000PD). This study was small (n = 24 and n = 49 in the two groups, respectively), and the intervention team was also assessing the appropriateness; thus, it was to be expected that the appropriateness postimplementation was high. It is unclear what resulted in the large reduction in drug utilisation, as only 8% of interventions (i.e. two interventions) targeted de-escalation or discontinuation of antibiotics. Katsios et al. from Canada emphasised appropriate documentation and treatment of sterile versus nonsterile cultures . The proportion of cultures treated increased for sterile sites and the ratio decreased for nonsterile sites. They noted a significant improvement in appropriate daily documentation for antibiotic courses including the medication, dose, route and duration, as well as de-escalation, if applicable. They also reported a reduction in antimicrobial utilisation and acquisition costs. A strength of this study was the unique goal to improve documentation through education as a component of audit and feedback, and measurement of the proportion of cultures treated as a surrogate for appropriate antibiotic usage. Rimawi et al. reported a significant improvement in guideline-concordant treatment and a reduction in utilisation of extended-spectrum penicillins, carbapenems, vancomycin and metronidazole, and antibiotic costs, but an increase in narrow-spectrum penicillins in a medical ICU in the USA . A significant improvement in patient outcomes was reported: reduced mechanical ventilation days, LOS, and hospital mortality. However, the mortality difference was only observed for overall hospital mortality, and not for ICU mortality; therefore, these differences in reported outcomes may not be directly attributable to the ASP intervention. Diaz Granados targeted imipenem and piperacillin/tazobactam in a USA community hospital . The acceptance rates for recommendations were comparably low (66.5%); however, they found an improvement in appropriate antimicrobial selection and resistance rates. They also reported a shorter overall and ICU LOS as well as shorter courses of treatment with similar mortality rates. Limitations included different patient populations in their study periods as well as their approach to quantifying resistance rates, which has neither been validated nor represents standard of practice for measurement. Finally, Leung et al. found a reduction in costs (36.2%) and antibiotic utilisation (38.9%) for antipseudomonal broad-spectrum antibiotics in a Canadian hospital . Their model included an ASP pharmacist and physician who conducted daily reviews of ICU patients. No significant differences in C. difficile infection rates or mortality rates were reported.
Finally, the study by Ijo et al. from the USA was the least rigorous from this group since the authors compared patient outcomes (LOS and mortality) during a 4-month ASP audit and feedback intervention with the published literature . They found a shorter LOS and similar mortality rates in the 70 patients included compared to the published literature.
Restriction and preauthorisation of specific anti-infectives is recommended by the IDSA guideline as an A-II recommendation to improve drug utilisation and reduce costs. All studies cited in the guidelines were single centre, non-ICU focused, and all but one study targeted parenteral antibiotics. Four of the studies required a verbal approval from an infectious diseases physician prior to release of the antibiotic [29–32] and three studies utilised clinical pharmacists to enforce restriction criteria [33–35].
We identified only three recent studies related to restriction and preauthorisation. Sistanizad et al. conducted a controlled quasi-experimental study in a teaching hospital in Iran . They restricted carbapenems for the treatment of documented multidrug-resistant organisms when no other therapeutic options were available in a medical ICU using the general ICU as the control group. Consequently, carbapenem use decreased significantly by 60% (from 68.6 to 27.5 DDD/1 000PD) while the overall antibiotic utilisation remained unchanged. Limitations of this study included potential for cross-contamination between the intervention and control unit since physicians were practicing in both settings and, subsequently, carbapenem utilisation also decreased in both units.
Guarascio et al. developed an “antifungal bundle” intervention that was implemented in a medical and surgical ICU at a university hospital in the USA in order to limit excessive use of echinocandins, with a clinical pharmacist providing daily reassessment of treatment . Historic controls were used for comparison in a matched cohort study design. The reduction in the medical ICU was significant (median DOT 4.0 vs 2.0) with a potential for cost savings of $1 013 per patient.
Finally, Sharma and Barman implemented and assessed the impact of an antibiotic restriction form that outlined appropriate indications for reserved antibiotics in a tertiary care hospital in India . They showed a reduction in carbapenem use from 18.8 at the beginning to 10.6 DDD/100 bed days at the end of a 4-month intervention and the antifungal use decreased from 56.1 to 22.1 DDD/100 bed days.
Guidelines, clinical pathways and mixed interventions
A combination of strategies will likely maximise the success of an ASP within an institution. Education, clinical pathways, antimicrobial cycling and integration of healthcare information technology are elements discussed in the IDSA guidelines .
Overall, we identified nine studies that evaluated guidelines, clinical pathways and/or mixed interventions in an ICU setting (table 2).
Evidenced-based guidelines and pathways
The IDSA guidelines highlighted that evidence-based guidelines developed by a multidisciplinary team incorporating local resistance patterns can improve antimicrobial utilisation as an A-III recommendation  based on two randomised controlled trials [39, 40] and three quasi-experimental studies [41–43].
We identified two recent uncontrolled quasi-experimental studies [44, 45]. Rodriguez et al. implemented a prophylactic antibiotic protocol precluding the use of aminoglycosides or glycopeptides for open fractures in a USA hospital . Use of these antibiotics was significantly reduced from 53.5% to 16.4% with no change in rates of surgical site infections.
Chiu et al. implemented a guideline restricting the use of vancomycin for late-onset sepsis in two tertiary care neonatal ICUs in the USA . Vancomycin start rates were significantly decreased from 6.9 and 17 to 4.5 and 6.4 per 1 000 patient-days, respectively. No statistical difference in the overall incidence of late-onset sepsis, meningitis, duration of bacteraemia and mortality were found.
Education is considered to be an important element of any intervention and is graded as A-III evidence in the IDSA guidelines. However, education alone is deemed to be marginally effective in modifying prescribing behaviour . This recommendation was based on two quasi-experimental studies [46, 47].
Meyer et al. provided teaching sessions on changing antibiotic prophylaxis to a single cefuroxime dose prior to central nervous system shunt insertion and found a significant reduction in cefuroxime use in a time-series analysis . Unexpectedly, the proportion of third generation resistant Escherichia coliincreased postintervention. Limitations included the absence of clinically meaningful data such as shunt-related infections, and the unexplained change in resistance rates. Chaves et al. provided quarterly education sessions, developed ICU-specific treatment guidelines and implemented a reminder on the medication record for proper documentation . Compared with the historical control, adherence to documentation standards significantly improved across all items: start date (72% to 90%), stop date (16% to 63%), indication (58% to 83%). Furthermore, antibiotic use concordance with national guidelines significantly improved from 74% to 89%.
Computerised decision support system
The recommendation of a computerised decision support system (CDSS) received a B-II grading in the IDSA guidelines . The majority of the studies discussed in the IDSA guidelines were single centre experiences in the USA [50–53]. In these quasi-experimental studies, the authors demonstrated that CDSS significantly reduced the number of pharmacy interventions and adverse drug reactions, decreased antimicrobial consumption and associated drug costs. The only randomised controlled trial was from Shojania et al., in which national guidelines advocating appropriate vancomycin use were incorporated into the hospital’s computerised physician order entry (CPOE) system , resulting in an overall reduction in vancomycin use and duration with no impact on patient-important outcomes reported.
More recently, Nachtigall et al. evaluated the impact of a CDSS that guided clinicians through a systematic, evidence-based approach in management of common infections in ICU, while addressing de-escalation strategies and targeted antibiotics following pathogen identification . Guideline adherence and antibiotic-free days increased significantly compared with the historical control. Finally, the authors also found a lower mortality in patients where CDSS was adhered to (8% vs 12.3%). Overall, this study demonstrated the sustained effects of a CDSS over a 5-year period; however, the generalisability may be limited owing to the predominantly surgical patient population.
Ananda-Rajah et al. implemented a bundle consisting of CDSS, twice-weekly infectious diseases physician rounds and enhanced infection control practices in a mixed medical-surgical ICU in Australia . Using time-series analysis, they reported a decrease in the Staphylococcus aureus incidence density by 83% (89% for methicillin-resistant Staph. aureus specifically) over the 8.5-year period and found a 26% decrease in broad-spectrum antibiotic utilisation. As a result of the bundle approach, however, the impact of individual interventions remained unknown.
Finally, Wilde et al implemented a computerised clinical pathway (CCP) to facilitate antimicrobial selection for ventilator-associated pneumonia treatment in the three ICUs of their tertiary care institution in USA . They achieved 100% compliance and 70.8% of patients received appropriate antibiotics within 24 hours of diagnosis of ventilator-associated pneumonia with mandatory use of CCP which was significantly better than voluntary use (44% and 56.3%, respectively). In addition, mandatory CCP shortened time to appropriate therapy and facilitated de-escalation in a greater proportion of patients.
In a mixed medical/surgical ICU in the USA, Slain et al. implemented prospective audit and feedback, formulary restriction and preauthorisation, education, pocket cards, and a ventilator-associated pneumonia antibiotic cycling protocol with streamlining and de-escalation in a step-wise fashion . Ciprofloxacin and ceftazidime use declined from 148 and 62.5 to 40 and 24.5 DDD/1 000PD, respectively, as did the overall use of antibiotics, but no effect on Pseudomonas aeruginosa resistance patterns was noted.
Similarly, Dortch et al. implemented routine bronchoscopy in cases of suspected pneumonia, surgical prophylaxis protocols, treatment guidelines and quarterly antibiotic cycling . The proportion of healthcare-associated infections caused by multidrug resistant Gram-negative pathogens decreased from 37.4% to 8.5% over 8 years. Antibiotic cycling appeared to have a significant association with a reduction of multidrug resistant healthcare-associated infections, although this was not the primary endpoint. The potential benefits and risks of antibiotic cycling, which received a C-II grading due to insufficient data in the IDSA guidelines, are beyond the scope of this review .
Biomarkers, in particular procalcitonin, are emerging as potentially very useful laboratory tests to aid in the diagnosis of bacterial infections such as respiratory infections  and sepsis [55, 56]. Numerous studies have found procalcitonin to be useful in various settings, including the emergency department  and ICU (table 3).
In 2013, Prkno et al. conducted a meta-analysis to evaluate the use of procalcitonin in patients with severe sepsis . They compared procalcitonin-guided therapy with standard of care, with mortality as the primary outcome. They included seven randomised controlled trials, four of which will be described in more detail [62–65]. Duration of antibiotics was reported in five studies and suggested a significant reduction in the median duration of antimicrobials in the procalcitonin guided group compared to the control group (hazard ratio 1.27, 95% confidence interval [CI] 1.01–1.53]) while mortality and ICU LOS remained unchanged. The authors noted a moderate risk of bias across the studies. Although there was no statistical heterogeneity, there was clinical heterogeneity with the use of different procalcitonin algorithms, targeting escalation, de-escalation or a combination thereof, and differences in patient populations. Finally, duration of therapy in the control arms varied.
Hochreiter et al. conducted a single centre, open-label randomised controlled trial in a surgical ICU in Germany . They included patients with confirmed or suspected bacterial infection and two or more systemic inflammatory response syndrome criteria comparing a procalcitonin-guided arm with an 8-day standard course. The authors found a significant reduction in the duration of treatment (5.9 vs 7.9 days) and in the LOS in the ICU. The frequency of overriding the protocol was unclear as was the proportion of patients with infections requiring greater than 8 days of therapy. Of note, using an 8-day course as a comparator is questionable since shorter treatment courses can be used in the absence of procalcitonin [66, 67].
Using a noninferiority open-label randomised controlled design in seven ICUs in France, Bouadma et al. assessed a procalcitonin-guided protocol to initiate or discontinue antimicrobials . The difference in mortality rates was within the 10% non-inferiority margin (21.2% vs 20.4%, risk difference 0.8 [95% CI −4.6 to 6.2] at 28 days). There was also a significant increase in antibiotic-free days from 11.6 to 14.3 days. There was no statistical difference in relapse, superinfection, number of days without mechanical ventilation, length of ICU or hospital stay. However, physicians overruled the procalcitonin algorithm 53% of the time. Furthermore, a 10% noninferiority margin for a mortality outcome is wide and the difference in mortality rates would not have met the noninferiority requirements with a smaller margin.
In another multicentre randomised controlled trial in nine ICUs in France reported by Annane et al., healthcare providers and investigators in the control arm were blinded to procalcitonin levels . They included patients who presented with severe sepsis, no clear infection source and negative microbial cultures. The study was stopped early because of low patient enrolment; therefore, the two groups were not balanced and the study was underpowered. They did not find a significant difference between the procalcitonin arm and the control group in the proportion of patients receiving antibiotics on day 5. Furthermore, there was a high rate of protocol deviation, with up to 37% of patients being managed outside of the algorithm recommendations at day 5.
In Denmark, Jensen et al. conducted another multicentre, open-label, randomised controlled trial across nine ICUs . In this escalation study, a procalcitonin level >1 mcg/l suggested expanding the antimicrobial coverage and searching for uncontrolled sources of infection. The primary outcome, 28-day survival, was similar. However, days of mechanical ventilation and median ICU LOS were significantly elevated in the procalcitonin arm. Antibiotic utilisation, particularly piperacillin-tazobactam and ciprofloxacin was increased in the procalcitonin arm. This may be explained by the large proportion of surgical patients in this study (41%), as surgical patients have elevated procalcitonin levels for other reasons, which may have prompted clinicians to continue antimicrobial therapy unnecessarily .
A more recent randomised controlled trial was published by Shehbabi et al. . They evaluated the effect of procalcitonin on antimicrobial prescribing across 11 Australian ICUs in addition to twice-weekly antimicrobial stewardship rounds. Duration of antibiotic treatment was similar (9 days; interquartile range [IQR] 6–21 vs 11 days; IQR 6–22), as were antibiotic-free days (20 days; IQR 11–22 vs 17 days; IQR 7–22). However, there was a significant reduction in total antimicrobial consumption in DDDs. No difference was reported in ICU LOS, total LOS, and in the 90-day all-cause mortality. Of note, the cut-offs used for the procalcitonin algorithm were lower than those that have been applied in other randomised controlled trials, potentially leading to no difference in duration of therapy.
Finally, in a German surgical ICU, Hohn et al. conducted a quasi-experimental study evaluating the implementation of a procalcitonin protocol with ASP (antibiotic prescription restricted to senior ICU physician, daily ASP rounds, regular teaching, and local guidelines) . There was a reduction in antimicrobial utilisation of 15.4% between 2010–2011 and 2011–2012, driven by a reduction of aminoglycosides, cephalosporins and fluoroquinolones, resulting in a reduction in antimicrobial costs by 43%. There was no difference in ICU LOS, and mortality rates. Owing to the bundle approach, it is unclear whether the effect is attributable to ASP, or to the use of procalcitonin.
A more extensive review of the literature for procalcitonin in the ICU setting was beyond the scope of this article, and we refer to the recently published review article by Albrich et al. .
|Table 2: Education, evidence-based guidelines and pathways, mixed interventions.|
|Author||Country||Year||Design||Patient population||ASP intervention(s)||Outcome and results|
|Adults; medical surgical ICU||CDSS, prospective audit and feedback, dedicated ICP||S. aureus incidence density: lower|
Rates of MRSA bacteraemia: lower
Broad spectrum abx: lower
|Chaves ||Australia||2010–2012||Quasi-experimental |
|Adults; medical & surgical ICU||Education, reminder stickers||Documentation (start/stop dates and indication): improved|
Abx concordant with guidelines: increased
|Neonates||Guideline (restriction of vancomycin)||Vancomycin use: lower|
Duration of bacteraemia, incidence of complications or death in late-onset sepsis: unchanged
|Dortch ||USA||2001–2008||Quasi-experimental |
|Adults; surgical and trauma ICU||Protocol and treatment guidelines + abx cycling + de-escalation (based on bronchoscopy results in suspected VAP)||% HAI due to MDR Gram-negative pathogens: lower |
% HAI due to pan-sensitive pathogens: higher
Rate of HAI due to MDR: lower
Interrupted time series
|Adults; surgical ICU||Comprehensive education on cerebrospinal shunt insertion prophylaxis||Abx use: lower|
Abx resistance: variable
|Nachtigall ||Germany||2006–2010||Cohort study||Adults; primarily surgical ICU units||CDSS||Adherence to treatment guidelines: higher |
Abx-free days: increased
|Level 1 trauma centre; adults with open extremity fractures||Evidence-based protocol for antibiotic prophylaxis||Abx utilisation (aminoglycosides and glycopeptides): lower|
|Adults; medical and surgical ICU||Prospective audit and feedback + formulary restriction + preauthorisation + education + VAP abx cycling protocol with streamlining/de-escalation||Abx utilisation (antipseudomonal agents): lower from 2004–2007, but increased 2008–10|
P. aeruginosa resistance rate: variable
|Adults; medical, surgical and neurotrauma ICU||CDSS (comparison was between mandatory versus voluntary use)||Appropriate Abx within 24 hours for VAP: unchanged|
|Abx = antibiotics; CDSS = computerised decision support system; HAI = hospital-acquired infections; ICP = infection control practitioner; MRSA = methicillin-resistant S. aureus; ICU = intensive care unit; SSTI = skin and soft tissue infection; VAP = ventilator-associated pneumonia|
|Table 3: Procalcitonin studies in the ICU setting.|
|Author||Country||Year||Design||Patient population||Procalcitonin protocol||Outcome and resultsesults|
|Annane ||France||2006–2009||Multicentre RCT||Medical/surgical ICU patients with sepsis (not microbiologically proven)|
n = 58
|No Abx when PCT <0.25 mcg/l and abx discouraged when PCT ≥0.25 mcg/l to <0.5 mcg/l||Proportion of abx treated patients at day 5: no difference|
|Bouadma ||France||2007–2008||Multicentre, open-label noninferiority RCT||Medical/surgical ICU|
n = 621
|Starting Abx if level >0.5 mcg/l|
Discontinuing Abx if PCT level <0.25 mcg/l, or decrease of >80% from peak concentration or PCT level ≥0.25 and <0.5 mcg/l
|Mortality: noninferiority for the PCT group vs standard care|
Abx-free days: higher in the PCT arm
|Hochreiter ||Germany||2006–2007||Single centre, open-label, RCT||Surgical ICU|
n = 110
|Discontinuation of abx if PCT level <1 mcg/l, or if PCT > 1 mcg/l but decreased 25–35% over 3 days vs standard care||Duration of therapy: reduced in PCT arm|
Length of ICU stay: reduced in PCT arm
|Hohn ||Germany||2010–2012||Single centre, retrospective quasi-experimental||Surgical ICU|
n = 2 422
|Discontinuation of abx when PCT <0.25 mcg/l, or –with clinical improvement – when PCT ≥0.25 to <0.5 mcg/l or PCT decreases to 10% of peak level||Abx use density: decrease|
|Jensen ||Denmark||2006–2009||Multicentre, open-label, RCT||Medical/surgical ICU|
n = 1 200
PCT level ≥1.0 mcg/l suggested to expand antimicrobial coverage or search for uncontrolled sources of infection.
|28-day mortality: no difference|
Days on mechanical ventilation: higher in the PCT arm
ICU LOS: higher in the PCT arm
|Prkno ||NA||NA||Systematic review and meta-analysis||7 studies|
n = 1 075 patients
|Variable||Hospital mortality: no difference|
28-day mortality: no difference
Duration of Abx: reduced
|Shehbabi ||Australia||2011–2012||Multi-centre RCT||Medical/surgical ICU|
n = 394
|Stop abx if PCT <0.1 mcg/l, if PCT is 0.1 to 0.25 mcg/l and infection was unlikely, or if PCT has decreased >90% from baseline||Time to Abx cessation: no difference|
Ab- free days: no difference
At day 28 total DDD: reduced in PCT group
Hospital LOS: no difference
90-day all-cause mortality: no difference
|abx = antibiotic; DDD = defined daily dose; ICU = intensive care unit; LOS = length of stay; PCT = procalcitonin, DDD = defined daily dose; RCT = randomised controlled trial|
The evidence for ASPs in the ICU setting is based on quasi-experimental studies with or without times-series analysis and/or control groups and – with the exception of studies on procalcitonin – no randomised controlled trials were identified. While individual-patient randomised controlled trials would not be feasible for the majority of interventions given the hospital-wide implementation of ASP and the risk of cross-contamination, cluster randomised controlled trials with or without a cross-over design would be feasible. The lack of randomisation increases vulnerability to both measured and unmeasured confounders. Also, in the absence of rigorous time-series analyses with an appropriate control group, these studies are at risk of bias as a result of temporal trends . While the impact of ASP intervention on appropriateness of antibiotics, utilisation and costs is fairly consistent across the studies, there is currently no convincing evidence that there is an effect on patient-important outcomes or resistance rates. One unpublished and not yet fully analysed study on audit and feedback from 11 academic hospitals with 14 participating ICUs in Ontario, Canada was recently conducted using a quasi-experimental stepped wedge design. Although again a nonrandomised study, the sample size of this study may allow for the detection of changes in patient-important outcomes as well as an impact on the antimicrobial susceptibility patterns.
Prospective audit and feedback received an A-I grading in the IDSA guideline based on two non-ICU randomised controlled trials . We identified several rigorously conducted quasi-experimental studies that used either time-series and/or a control group; thus, there is good evidence suggesting that audit and feedback has a positive impact on antibiotic utilisation in the ICU setting. However, given the lack of evidence from randomised controlled trials, our confidence in this finding is low when using GRADE terminology .
Formulary restrictions and preauthorisation is listed as an A-II recommendation in the IDSA guidelines . Despite the high grading of the evidence in the guideline, we found a small number of recent studies on this topic. This might be related to the common concern of a “squeezing the balloon” phenomenon for this type of approach : restriction of certain classes of antibiotics may result in a reduction in use and resistance rates, but without additional measures in place, it may also result in a shift to a higher usage of other antibiotics [32, 33, 35], thus negatively affecting the resistance rates for those alternative antibiotics. The previous evidence summarised in the IDSA guidelines  suggesting that restriction and preauthorisation impact antibiotic utilisation was corroborated by the more recent studies, but downstream effects due to increased use of other antibiotics was not assessed in these studies. Similar to other strategies, the lack of randomised controlled trials results in a low level of evidence for these strategies.
The use of education, evidence-based guidelines and pathways, CDSS and mixed interventions are all endorsed by IDSA . Our review of the literature found that the majority were uncontrolled quasi-experimental studies. Existing evidence appears to suggest that any of these interventions, alone or in combination, have a positive impact on process measures such as adherence rate or antimicrobial utilisation. Results on clinically relevant outcomes such as infection rates or resistant patterns were variable. The absence of randomised controlled trials and inclusion of multiple components in the intervention are two recurring challenges when reviewing this group of literature. Given these limitations, we can assign only a low grading.
The use of procalcitonin in the ICU setting has been well studied in numerous randomised controlled trials and the findings are promising in terms of reduction of antibiotic use without negatively affecting patient outcomes. While the majority of studies favoured the procalcitonin arm, one large procalcitonin-escalation study found a negative impact on antibiotic utilisation as well as on days on mechanical ventilation and LOS . Several limitations were identified: there was significant heterogeneity in protocols, with some studies using procalcitonin to initiate, others to discontinue antibiotics or both. In addition, there is variability in the procalcitonin cut-offs that were used. The populations studied are heterogeneous, as some studies evaluated medical/surgical patients whereas others looked predominately at surgical patients. Only two studies from our review explicitly stated there were ASPs present in the ICUs [69, 70]; thus, the added value of procalcitonin within a strong ASP remains unclear. Furthermore, there was significant deviation from the procalcitonin-protocol noted [62, 63]. Finally, costs remain a concern given the comparably high costs for testing, although a recent cost-minimisation and cost-utility study suggested improved patient quality of life with reduced costs in ICU patients with bacterial infections and sepsis . Overall, there is a moderate level of evidence supporting the use of procalcitonin to reduce duration of antibiotics in the ICU setting.
While we found overall convincing data – within the limitations of nonrandomized studies- that most stewardship strategies are potentially effective in reducing and optimizing antibiotic utilisation, the impact on patient-important outcomes has been variable with no convincing evidence at this point. The absence of such evidence does not imply ASP strategies in the ICU setting are not beneficial to patient-important outcomes, but their detection is difficult given the small event rates of failures, and the lag time until effects may affect future patients, for example, due to reduction of the emergence of resistance. Future studies should be large, i.e. multi-centre studies, optimally using a cluster randomised control trial design or at least controlled quasi-experimental studies with time-series analysis over a prolonged period of time in order to be able to identify the impact of ASP on patient-important outcomes and on the emergence of resistance.
Disclosure statement: DM is a recipient of a Research Early Career Award from Hamilton Health Sciences Foundation (Jack Hirsh Fellowship).
Correspondence: Dominik Mertz, Assistant Professor, McMaster University, Department of Medicine, Division of Infectious Diseases, Associate Appointment Department of Clinical Epidemiology and Biostatistics, Medical Director Infection Prevention & Control, Hamilton Health Sciences, Juravinski Hospital and Cancer Center, 711 Concession Street, Section M, Level 1, Room 3, Hamilton, ON, L8V 1C3, Canada, mertzd[at]mcmaster.ca
1 Dellit TH, Owens RC, McGowan JE, Jr., et al. Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America guidelines for developing an institutional program to enhance antimicrobial stewardship. Clin Infect Dis. 2007;44(2):159–77.
2 Srigley JA, Brooks A, Sung M, Yamamura D, Haider S, Mertz D. Inappropriate use of antibiotics and Clostridium difficile infection. Am J Infect Control. 2013;41(11):1116–8.
3 Polgreen PM, Chen YY, Cavanaugh JE, et al. An outbreak of severe Clostridium difficile-associated disease possibly related to inappropriate antimicrobial therapy for community-acquired pneumonia. Infect Control Hosp Epidemiol. 2007;28(2):212–4.
4 Cusini A, Rampini SK, Bansal V, et al. Different patterns of inappropriate antimicrobial use in surgical and medical units at a tertiary care hospital in Switzerland: a prevalence survey. PLoS One. 2010;5(11):e14011.
5 Bugnon-Reber A, de Torrente A, Troillet N, Genne D. Antibiotic misuse in medium-sized Swiss hospitals. Swiss Med Wkly. 2004;134(33-34):481–5.
6 Reimann HA. The misuse of antimicrobics. Med Clin North Am. 1961;45:849–56.
7 Blaettler L, Mertz D, Frei R, et al. Secular trend and risk factors for antimicrobial resistance in Escherichia coli isolates in Switzerland 1997–2007. Infection. 2009;37(6):534–9.
8 Ansari F, Erntell M, Goossens H, Davey P. The European surveillance of antimicrobial consumption (ESAC) point-prevalence survey of antibacterial use in 20 European hospitals in 2006. Clin Infect Dis. 2009;49(10):1496–504.
9 McGowan JE, Jr. Economic impact of antimicrobial resistance. Emerg Infect Dis. 2001;7(2):286–92.
10 Cosgrove SE, Carmeli Y. The impact of antimicrobial resistance on health and economic outcomes. Clin Infect Dis. 2003;36(11):1433–7.
11 Johnson AP, Woodford N. Global spread of antibiotic resistance: the example of New Delhi metallo-beta-lactamase (NDM)-mediated carbapenem resistance. J Med Microbiol. 2013;62(Pt 4):499–513.
12 Boucher HW, Talbot GH, Benjamin DK, Jr., et al. 10 x '20 Progress – development of new drugs active against gram-negative bacilli: an update from the Infectious Diseases Society of America. Clin Infect Dis. 2013;56(12):1685–94.
13 Aldeyab MA, Harbarth S, Vernaz N, et al. Quasiexperimental study of the effects of antibiotic use, gastric acid-suppressive agents, and infection control practices on the incidence of Clostridium difficile-associated diarrhea in hospitalized patients. Antimicrob Agents Chemother. 2009;53(5):2082–8.
14 Kumar A, Roberts D, Wood KE, et al. Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in human septic shock. Crit Care Med. 2006;34(6):1589–96.
15 Kaki R, Elligsen M, Walker S, Simor A, Palmay L, Daneman N. Impact of antimicrobial stewardship in critical care: a systematic review. J Antimicrob Chemother. 2011;66(6):1223–30.
16 Fraser GL, Stogsdill P, Dickens JD, Jr., Wennberg DE, Smith RP, Jr., Prato BS. Antibiotic optimization. An evaluation of patient safety and economic outcomes. Arch Intern Med. 1997;157(15):1689–94.
17 Solomon DH, Van Houten L, Glynn RJ, et al. Academic detailing to improve use of broad-spectrum antibiotics at an academic medical center. Arch Intern Med. 2001;161(15):1897–902.
18 Carling P, Fung T, Killion A, Terrin N, Barza M. Favorable impact of a multidisciplinary antibiotic management program conducted during 7 years. Infect Control Hosp Epidemiol. 2003;24(9):699–706.
19 LaRocco A, Jr. Concurrent antibiotic review programs – a role for infectious diseases specialists at small community hospitals. Clin Infect Dis. 2003;37(5):742–3.
20 Elligsen M, Walker SA, Pinto R, et al. Audit and feedback to reduce broad-spectrum antibiotic use among intensive care unit patients: a controlled interrupted time series analysis. Infect Control Hosp Epidemiol. 2012;33(4):354–61.
21 Wang HY, Chiu CH, Huang CT, et al. Blood culture-guided de-escalation of empirical antimicrobial regimen for critical patients in an online antimicrobial stewardship programme. Int J Antimicrob Agents. 2014;44(6):520–7.
22 Bornard L, Dellamonica J, Hyvernat H, et al. Impact of an assisted reassessment of antibiotic therapies on the quality of prescriptions in an intensive care unit. Med Mal Infect. 2011;41(9):480–5.
23 Amer MR, Akhras NS, Mahmood WA, Al-Jazairi AS. Antimicrobial stewardship program implementation in a medical intensive care unit at a tertiary care hospital in Saudi Arabia. Ann Saudi Med. 2013;33(6):547–54.
24 DiazGranados CA. Prospective audit for antimicrobial stewardship in intensive care: impact on resistance and clinical outcomes. Am J Infect Control. 2012;40(6):526–9.
25 Katsios CM, Burry L, Nelson S, et al. An antimicrobial stewardship program improves antimicrobial treatment by culture site and the quality of antimicrobial prescribing in critically ill patients. Crit Care. 2012;16(6):R216.
26 Leung V, Gill S, Sauve J, Walker K, Stumpo C, Powis J. Growing a “positive culture” of antimicrobial stewardship in a community hospital. Can J Hosp Pharm. 2011;64(5):314–20.
27 Rimawi RH, Mazer MA, Siraj DS, Gooch M, Cook PP. Impact of regular collaboration between infectious diseases and critical care practitioners on antimicrobial utilization and patient outcome. Crit Care Med. 2013;41(9):2099–107.
28 Ijo I, Feyerharm J. Pharmacy intervention on antimicrobial management of critically ill patients. Pharm Pract (Granada). 2011;9(2):106–9.
29 Seligman SJ. Reduction in antibiotic costs by restricting use of an oral cephalosporin. Am J Med. 1981;71(6):941–4.
30 Coleman RW, Rodondi LC, Kaubisch S, Granzella NB, O’Hanley PD. Cost-effectiveness of prospective and continuous parenteral antibiotic control: experience at the Palo Alto Veterans Affairs Medical Center from 1987 to 1989. Am J Med. 1991;90(4):439–44.
31 Maswoswe JJ, Okpara AU. Enforcing a policy for restricting antimicrobial drug use. Am J Health Syst Pharm. 1995;52(13):1433–5.
32 White AC, Jr., Atmar RL, Wilson J, Cate TR, Stager CE, Greenberg SB. Effects of requiring prior authorization for selected antimicrobials: expenditures, susceptibilities, and clinical outcomes. Clin Infect Dis. 1997;25(2):230–9.
33 Britton HL, Schwinghammer TL, Romano MJ. Cost containment through restriction of cephalosporins. Am J Hosp Pharm. 1981;38(12):1897–900.
34 Hayman JN, Sbravati EC. Controlling cephalosporin and aminoglycoside costs through pharmacy and therapeutics committee restrictions. Am J Hosp Pharm. 1985;42(6):1343–7.
35 Woodward RS, Medoff G, Smith MD, Gray JL, 3rd. Antibiotic cost savings from formulary restrictions and physician monitoring in a medical-school-affiliated hospital. Am J Med. 1987;83(5):817–23.
36 Sistanizad M, Kouchek M, Miri M, et al. Carbapenem Restriction and its Effect on Bacterial Resistance in an Intensive Care unit of a Teaching Hospital. Iran J Pharm Res. 2013;12(3):503–9.
37 Guarascio AJ, Slain D, McKnight R, et al. A matched-control evaluation of an antifungal bundle in the intensive care unit at a university teaching hospital. Int J Clin Pharm. 2013;35(1):145–8.
38 Sharma PR, Barman P. Antimicrobial consumption and impact of “Reserve antibiotic indent form” in an intensive care unit. Indian J Pharmacol. 2010;42(5):297–300.
39 Marrie TJ, Lau CY, Wheeler SL, Wong CJ, Vandervoort MK, Feagan BG. A controlled trial of a critical pathway for treatment of community-acquired pneumonia. CAPITAL Study Investigators. Community-Acquired Pneumonia Intervention Trial Assessing Levofloxacin. JAMA. 2000;283(6):749–55.
40 Singh N, Rogers P, Atwood CW, Wagener MM, Yu VL. Short-course empiric antibiotic therapy for patients with pulmonary infiltrates in the intensive care unit. A proposed solution for indiscriminate antibiotic prescription. Am J Respir Crit Care Med. 2000;162(2 Pt 1):505–11.
41 Price J, Ekleberry A, Grover A, et al. Evaluation of clinical practice guidelines on outcome of infection in patients in the surgical intensive care unit. Crit Care Med. 1999;27(10):2118–24.
42 Ibrahim EH, Ward S, Sherman G, Schaiff R, Fraser VJ, Kollef MH. Experience with a clinical guideline for the treatment of ventilator-associated pneumonia. Crit Care Med. 2001;29(6):1109–15.
43 South M, Royle J, Starr M. A simple intervention to improve hospital antibiotic prescribing. Med J Aust. 2003;178(5):207–9.
44 Chiu CH, Michelow IC, Cronin J, Ringer SA, Ferris TG, Puopolo KM. Effectiveness of a guideline to reduce vancomycin use in the neonatal intensive care unit. Pediatr Infect Dis J. 2011;30(4):273–8.
45 Rodriguez L, Jung HS, Goulet JA, Cicalo A, Machado-Aranda DA, Napolitano LM. Evidence-based protocol for prophylactic antibiotics in open fractures: improved antibiotic stewardship with no increase in infection rates. J Trauma Acute Care Surg. Sep 2014;77(3):400–7; discussion 407–8; quiz 524.
46 Bantar C, Sartori B, Vesco E, et al. A hospitalwide intervention program to optimize the quality of antibiotic use: impact on prescribing practice, antibiotic consumption, cost savings, and bacterial resistance. Clin Infect Dis. 2003;37(2):180–6.
47 Girotti MJ, Fodoruk S, Irvine-Meek J, Rotstein OD. Antibiotic handbook and pre-printed perioperative order forms for surgical antibiotic prophylaxis: do they work? Can J Surg. 1990;33(5):385–8.
48 Meyer E, Schwab F, Pollitt A, Bettolo W, Schroeren-Boersch B, Trautmann M. Impact of a change in antibiotic prophylaxis on total antibiotic use in a surgical intensive care unit. Infection. 2010;38(1):19–24.
49 Chaves NJ, Ingram RJ, MacIsaac CM, Buising KL. Sticking to minimum standards: implementing antibiotic stewardship in intensive care. Intern Med J. 2014;44(12a):1180–7.
50 Evans RS, Pestotnik SL, Classen DC, et al. A computer-assisted management program for antibiotics and other antiinfective agents. N Engl J Med. 1998;338(4):232–8.
51 Evans RS, Pestotnik SL, Classen DC, Burke JP. Evaluation of a computer-assisted antibiotic-dose monitor. Ann Pharmacother. 1999;33(10):1026–31.
52 Pestotnik SL, Classen DC, Evans RS, Burke JP. Implementing antibiotic practice guidelines through computer-assisted decision support: clinical and financial outcomes. Ann Intern Med. 1996;124(10):884–90.
53 Mullett CJ, Evans RS, Christenson JC, Dean JM. Development and impact of a computerized pediatric antiinfective decision support program. Pediatrics. 2001;108(4):E75.
54 Shojania KG, Yokoe D, Platt R, Fiskio J, Ma’luf N, Bates DW. Reducing vancomycin use utilizing a computer guideline: results of a randomized controlled trial. J Am Med Inform Assoc. 1998;5(6):554–62.
55 Nachtigall I, Tafelski S, Deja M, et al. Long-term effect of computer-assisted decision support for antibiotic treatment in critically ill patients: a prospective “before/after” cohort study. BMJ Open. 2014;4(12):e005370.
56 Ananda-Rajah MR, McBryde ES, Buising KL, et al. The role of general quality improvement measures in decreasing the burden of endemic MRSA in a medical-surgical intensive care unit. Intensive Care Med. 2010;36(11):1890–8.
57 Wilde AM, Nailor MD, Nicolau DP, Kuti JL. Inappropriate antibiotic use due to decreased compliance with a ventilator-associated pneumonia computerized clinical pathway: implications for continuing education and prospective feedback. Pharmacotherapy. 2012;32(8):755–63.
58 Slain D, Sarwari AR, Petros KO, et al. Impact of a Multimodal Antimicrobial Stewardship Program on Pseudomonas aeruginosa Susceptibility and Antimicrobial Use in the Intensive Care Unit Setting. Crit Care Res Pract. 2011;2011:416426.
59 Dortch MJ, Fleming SB, Kauffmann RM, Dossett LA, Talbot TR, May AK. Infection reduction strategies including antibiotic stewardship protocols in surgical and trauma intensive care units are associated with reduced resistant gram-negative healthcare-associated infections. Surg Infect (Larchmt). 2011;12(1):15–25.
60 Hausfater P, Garric S, Ayed SB, Rosenheim M, Bernard M, Riou B. Usefulness of procalcitonin as a marker of systemic infection in emergency department patients: a prospective study. Clin. Infect. Dis. 2002;34(7):895–901.
61 Prkno A, Wacker C, Brunkhorst FM, Schlattmann P. Procalcitonin-guided therapy in intensive care unit patients with severe sepsis and septic shock – a systematic review and meta-analysis. Crit. Care. 2013;17(6):R291.
62 Annane D, Maxime V, Faller JP, et al. Procalcitonin levels to guide antibiotic therapy in adults with non-microbiologically proven apparent severe sepsis: a randomised controlled trial. BMJ Open. 2013;3(2).
63 Bouadma L, Luyt CE, Tubach F, et al. Use of procalcitonin to reduce patients' exposure to antibiotics in intensive care units (PRORATA trial): a multicentre randomised controlled trial. Lancet. 2010;375(9713):463–74.
64 Hochreiter M, Kohler T, Schweiger AM, et al. Procalcitonin to guide duration of antibiotic therapy in intensive care patients: a randomized prospective controlled trial. Crit Care. 2009;13(3):R83.
65 Jensen JU, Hein L, Lundgren B, et al. Procalcitonin-guided interventions against infections to increase early appropriate antibiotics and improve survival in the intensive care unit: a randomized trial. Crit Care Med. 2011;39(9):2048–58.
66 Sawyer RG, Claridge JA, Nathens AB, et al. Trial of short-course antimicrobial therapy for intraabdominal infection. N Engl J Med. 2015;372(21):1996–2005.
67 Solomkin JS, Mazuski JE, Bradley JS, et al. Diagnosis and management of complicated intra-abdominal infection in adults and children: guidelines by the Surgical Infection Society and the Infectious Diseases Society of America. Clin Infect Dis. 2010;50(2):133–64.
68 Clec’h C, Fosse JP, Karoubi P, et al. Differential diagnostic value of procalcitonin in surgical and medical patients with septic shock. Crit Care Med. 2006;34(1):102–7.
69 Shehabi Y, Sterba M, Garrett PM, et al. Procalcitonin algorithm in critically ill adults with undifferentiated infection or suspected sepsis. A randomized controlled trial. Am J Respir Crit Care Med. 2014;190(10):1102–10.
70 Hohn A, Heising B, Hertel S, Baumgarten G, Hochreiter M, Schroeder S. Antibiotic consumption after implementation of a procalcitonin-guided antimicrobial stewardship programme in surgical patients admitted to an intensive care unit: a retrospective before-and-after analysis. Infection. 2015.
71 Albrich WC, Harbarth S. Pros and cons of using biomarkers versus clinical decisions in start and stop decisions for antibiotics in the critical care setting. Intensive Care Med. 2015.
72 Angebault C, Andremont A. Antimicrobial agent exposure and the emergence and spread of resistant microorganisms: issues associated with study design. Eur J Clin Microbiol Infect Dis. 2013;32(5):581–95.
73 Atkins D, Best D, Briss PA, et al. Grading quality of evidence and strength of recommendations. BMJ. 2004;328(7454):1490.
74 Burke JP. Antibiotic resistance – squeezing the balloon? JAMA. 1998;280(14):1270–1.
75 Harrison M, Collins CD. Is procalcitonin-guided antimicrobial use cost-effective in adult patients with suspected bacterial infection and sepsis? Infect Control Hosp. Epidemiol. 2015;36(3):265–72.
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