Blood pressure control and antihypertensive treatment in Swiss general practice: a cross-sectional study using routine data

DOI: https://doi.org/https://doi.org/10.57187/s.3898

Stefania Di Gangia*, Roman Brennerb*, Thomas Grischotta, Jakob Martin Burgstallera, Oliver Senna, Thomas Rosemanna, Stefan Markuna

Institute of Primary Care, University Hospital Zurich, University of Zurich, Zurich, Switzerland

Department of Cardiology, Kantonsspital St. Gallen, St. Gallen, Switzerland

Shared first authorship

Summary

AIMS OF THE STUDY: Arterial hypertension is a major global health risk. Global surveys indicate that only half of patients with arterial hypertension receive pharmacotherapy, and only a quarter achieve the primary blood pressure target recommended by guidelines. This study aimed to evaluate the achievement of the primary blood pressure target in Swiss general practice, provide insights into arterial hypertension treatment, and identify factors associated with achieving this goal.

METHODS: This cross-sectional study utilised data from a large Swiss primary care database. Patients with arterial hypertension, aged ≥18 years, who underwent blood pressure monitoring in 2021 were included. The primary observation was blood pressure control, defined as the achievement of the primary blood pressure target of systolic blood pressure <140 mm Hg and diastolic blood pressure <90 mm Hg. Demographic data from physicians and patients, blood pressure measurements, comorbidities, cardiovascular risk factors, and pharmacotherapy were collected, and arterial hypertension stages were calculated. Unadjusted and multivariable-adjusted mixed logistic regression models were used to identify factors associated with blood pressure control.

RESULTS: A total of 49,290 patients were included, of whom 23,933 (48.6%) were female. The median patient age was 71 years (interquartile range 61–80). Blood pressure control was observed in 23,022 patients (46.7%), and 36,692 patients (74.4%) had an antihypertensive pharmacotherapy prescription. In multivariable analysis, blood pressure control was positively associated with arterial hypertension stage, antihypertensive pharmacotherapy, the intensity of blood pressure monitoring, and the number of blood pressure-increasing drugs, but negatively associated with a long-standing arterial hypertension, female sex, and old age.

CONCLUSIONS: While general practitioners appear to consider arterial hypertension stages in their treatment strategies, there is still room for improvement in arterial hypertension care by prescribing pharmacotherapy, especially in patients with long-standing arterial hypertension, female sex and old age.

Abbreviations

ACEI:

angiotensin-converting enzyme inhibitor

ARB:

angiotensin receptor blocker

CCB:

calcium channel blocker

ESC:

European Society of Cardiology

ESH:

European Society of Hypertension

Introduction

Arterial hypertension affects approximately 10% of the global population and is the leading cause of cardiovascular diseases and premature mortality worldwide [1, 2]. Along with lifestyle modifications, lowering blood pressure with pharmacotherapy is the mainstay of arterial hypertension treatment and is supported by strong evidence demonstrating its beneficial effects on key outcomes [3, 4]. Numerous trials have evaluated the optimal treatment goals for pharmacotherapy in arterial hypertension, based on blood pressure levels and patient characteristics [4–6]. However, the evidence is less clear for older patients [7–9]. Given the potential side effects of arterial hypertension pharmacotherapy and the risk of treatment discontinuation, the 2018 European Society of Cardiology (ESC) / European Society of Hypertension (ESH) guidelines for the management of arterial hypertension recommend a stepwise approach to achieve blood pressure targets: a primary blood pressure goal, and for patients who tolerate treatment well, a secondary goal [10].

Achieving the primary blood pressure target of systolic blood pressure <140 mm Hg and diastolic blood pressure <90 mm Hg is commonly referred to as blood pressure control [11]. The proportion of arterial hypertension patients with blood pressure control is frequently used as a performance indicator for the quality of hypertension care [11]. Despite this, global surveys continue to show substantial evidence-to-practice gaps, with only half of the patients with arterial hypertension receiving pharmacotherapy and only a quarter with blood pressure control [12, 13]. In Switzerland, a 2009 study reported blood pressure control in approximately 50% of patients receiving antihypertensive pharmacotherapy [14]. However, blood pressure control is influenced by both patient- and physician-related factors, which need further exploration as potential enhancers or detractors. While limited data exist on physician characteristics as predictors of blood pressure control, all relevant variables should be assessed to identify potential targets for interventions aimed at improving the quality of arterial hypertension care.

Therefore, to consolidate the epidemiological basis for better arterial hypertension management, this study primarily seeks to provide updated insights into blood pressure control in Swiss general practice and, secondarily, to identify factors associated with blood pressure control, including arterial hypertension stage, pharmacotherapy, and patient and physician characteristics.

Materials and methods

Study design, setting, participants and ethics statement

We conducted a cross-sectional study based on data from Family Medicine Research using Electronic Medical Records (FIRE), a large Swiss general practice database established in 2009 [15]. The database currently includes data from 750 individual general practitioners and over 12 million consultation records, including administrative information, laboratory test results, vital sign measurements, and pharmacotherapy prescriptions. For this study, we included general practitioners who contributed data in 2021. Patient inclusion criteria were as follows: arterial hypertension diagnosis before 2021, age ≥18 years, and blood pressure monitoring during 2021 (i.e., at least one office blood pressure measurement recorded in 2021). Arterial hypertension was defined as at least one of the following at any time during the patient's medical history: (1) antihypertensive drug therapy as defined by the Swiss Pharmaceutical Cost Group [16]; (2) a general practitioner-assigned reason for encounter codes K85, K86, or K87 of the International Classification of Primary Care, 2nd edition (ICPC-2) [17]; or (3) at least two office-based blood pressure measurements with systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg each, with the second confirmatory measurement collected within 7 days to 6 months of the first, or a single blood pressure measurement of systolic blood pressure ≥180 mm Hg or diastolic blood pressure ≥110 mm Hg without a second confirmatory measurement [10, 18].

The local ethics committee of the Canton of Zurich waived approval for this study as it was based on anonymised data and thus fell outside the scope of the Swiss Federal Act on Research Involving Human Beings (BASEC-Nr. Req2017–00797).

Database query and definitions

For each patient, the last available blood pressure measurement in 2021 was defined as the index measurement. The most recent information prior to the index measurement was used to determine sex, age (continuous and categorical variables: <30, 30–64, 65–80, >80 years, or <65, ≥65 years as appropriate), and comorbidities (obesity, chronic kidney disease, dyslipidaemia, diabetes mellitus, and cardiovascular disease, as defined in appendix table S1, according to established methods [19, 20]). To capture active antihypertensive pharmacotherapy at the time of the index measurement, we queried all antihypertensive medications documented in the 5 years preceding the index measurement that had not been subsequently discontinued, based on their Anatomical Therapeutic Chemical (ATC) codes [21]. Data on potentially blood pressure-increasing pharmacotherapy were considered from 3 months prior to the index measurement.

Antihypertensive drugs were divided into the following classes: angiotensin-converting enzyme inhibitors (ACEI), angiotensin II receptor blockers (ARB), beta-blockers, calcium channel blockers (CCB), diuretics, and other antihypertensives (list of ATC codes is provided in appendix table S2). The following were classified as blood pressure-increasing drugs: antidepressants, oestrogens or testosterone, stimulants, anti-obesity agents, decongestants, antipsychotics, and systemic preparations of non-steroidal anti-inflammatory drugs (NSAIDs) and steroids (table S2) [22]. For combination drugs, each antihypertensive/blood pressure-increasing component was counted towards the total number of prescribed medications. Antihypertensive treatment intensity was classified as monotherapy, dual therapy, triple therapy, or more than three antihypertensive substances.

Arterial hypertension stages 1 to 3 were determined using the definitions outlined in the 2018 ESC guidelines for the management of arterial hypertension [10] and adapted to the variables available in FIRE (table S3 in the appendix). According to these guidelines [10], arterial hypertension was classified as controlled when the primary blood pressure goal was achieved (systolic blood pressure [SBP] <140 mm Hg and diastolic blood pressure [DBP] <90 mm Hg), with further sub-classification based on the achievement of the secondary blood pressure goal (age <65 years: SBP <130 mm Hg and DBP <80 mm Hg; age ≥65 years: SBP <140 mm Hg and DBP <80 mm Hg). Arterial hypertension was classified as uncontrolled when the primary blood pressure goal was not achieved (SBP ≥140 mm Hg or DBP ≥90 mm Hg), with further sub-classification into uncontrolled systolic (SBP ≥140 mm Hg and DBP <90 mm Hg), uncontrolled diastolic (SBP <140 mm Hg and DBP ≥90 mm Hg) or uncontrolled combined systolic-diastolic (SBP ≥140 mm Hg and DBP ≥90 mm Hg). Patients with uncontrolled arterial hypertension were further classified as having resistant arterial hypertension if they were taking antihypertensive medications from three or more different drug classes at the time of the index measurement, including a diuretic.

The general practitioner characteristics collected were: age (both continuous and categorical variables: ≤50, >50 years), sex, type of practice organisation (single, double, or group practice), working position (employee, self-employed), workload (expressed as percentage of full-time equivalent) in the practice, and the practice’s postal code, which was used to identify the practice’s location area (urban, suburban, rural) according to the Eurostat Degree of Urbanisation index for Switzerland [23].

Observations

The primary observation was blood pressure control, defined as the achievement of the primary blood pressure goal (yes, no). Secondary observations included the achievement of the secondary blood pressure goal (yes, no) and arterial hypertension pharmacotherapy (categorical), as defined above in terms of drug classes and treatment intensity.

We considered the following variables as potential factors associated with blood pressure control: (3a) patient-related: age (categorical: <65, ≥65 years), sex, arterial hypertension stage, pharmacotherapy for arterial hypertension (yes, no), number of blood pressure-increasing drugs used (categorical: 0, 1, ≥2), long-lasting arterial hypertension diagnosis (≥5 years: yes, no), intensity of blood pressure monitoring in 2021 (categorical: ≤5, >5 measurements); (3b) general practitioner-related: age (categorical), sex, practice organisation, working position and workload, and practice location area.

Statistical analysis

Summary statistics were presented as numbers (n) and percentages (%) for categorical and binary variables, and as mean and standard deviation (SD) or median and interquartile range (IQR), as appropriate, for continuous variables. An available case analysis was performed. Blood pressure control and the achievement of the secondary blood pressure goal were presented as proportions of all included patients and within each arterial hypertension stage and age group, with the latter stratification represented graphically. Descriptive statistics for arterial hypertension pharmacotherapy were reported overall and stratified by patients with and without blood pressure control. To identify factors associated with blood pressure control, both unadjusted (univariable) and multivariable-adjusted mixed logistic regression models were used. Random intercept effects were included at the general practitioner level to account for correlations between patients cared for by the same general practitioner. Predictors for the multivariable final model were selected using a stepwise backward approach, starting from a full model that included all variables with p <0.2 in univariable analyses. Multicollinearity was assessed using the variance inflation factor (VIF), generalised for logistic regression, for each predictor.

The results of the regression analyses were reported as odds ratios (OR) with 95% confidence intervals (CI). The final model results were represented in an odds ratio (OR) plot.

Test results were considered statistically significant at p ≤0.05. All analyses were conducted using the R statistical package, version 4.1.0 [24], with additional packages: dplyr version 1.1.2, tidyverse version 2.0.0, tableone version 0.13.2, ggplot2 version 3.4.2, finalfit version 1.0.6, ggVennDiagram version 1.2.2.

Results

Patient characteristics

We identified 458,240 eligible patients in the FIRE database, with 49,290 meeting the inclusion criteria (figures S1–S2 in the appendix, for the full inclusion process and identification criteria). Patient characteristics, overall and stratified by arterial hypertension stage, are shown in table 1. Of the total patient cohort, 23,933 (48.6%) were women. The median patient age was 71 years (IQR 61–80). The most prevalent comorbidities were dyslipidaemia, obesity, and cardiovascular disease, affecting 22,764 (46.2%), 14,582 (29.6%), and 13,631 (27.7%) patients, respectively.

Table 1Demographic characteristics, comorbidities, and blood pressure characteristics at the index measurement of the 49,290 patients included, overall and stratified by arterial hypertension stage.

Overall Stage 1 arterial hypertension Stage 2 arterial hypertension Stage 3 arterial hypertension
Total, n (%) 49,290 24,302 (49.3) 10,897 (22.1) 14,091 (28.6)
Demographic characteristics Sex* (female) n (%) 23,933 (48.6) 12,454 (51.2) 5533 (50.8) 5946 (42.2)
Age (years) median (IQR) 71 (61–80) 66 (56–75) 74 (63–82) 77 (69–83)
Co-occurring conditions**, n (%) Obesity 14,582 (29.6) 6327 (26.0) 4134 (37.9) 4121 (29.2)
Chronic kidney disease 7695 (15.6) 511 (2.1) 3402 (31.3) 3782 (26.8)
Chronic kidney disease grade 3 or higher 6300 (12.8) 0 (0.0) 3171 (29.1) 3129 (22.2)
Dyslipidaemia 22,764 (46.2) 7427 (30.6) 5007 (45.9) 10,330 (73.3)
History of smoking 909 (1.9) 347 (1.6) 174 (1.6) 388 (2.8)
Diabetes mellitus 11,709 (23.8) 0 (0.0) 7063 (64.8) 4646 (33.0)
Cardiovascular disease 13,631 (27.7) 0 (0.0) 0 (0.0) 13,631 (96.7)
– Heart failure or atrial fibrillation 2027 (4.1) 0 (0.0) 0 (0.0) 2027 (14.4)
– Obstructive atherosclerotic disease 12,444 (25.2) 0 (0.0) 0 (0.0) 12,444 (88.3)
– Pulmonary heart disease 40 (0.0) 0 (0.0) 0 (0.0) 40 (0.0)
Blood pressure index measurement, mean (SD) Systolic blood pressure (mm Hg) 139.9 (18.7) 141.1 (18.2) 139.1 (18.8) 138.6 (19.3)
Diastolic blood pressure (mm Hg) 81.9 (11.4) 84.5 (10.9) 80.6 (11.1) 78.6 (11.3)
Blood pressure goal achievement, n (%) Primary (i.e., blood pressure control) 23,022 (46.7) 10,379 (42.7) 5439 (49.9) 7204 (51.1)
Secondary 12,411 (25.2) 4619 (19.0) 3127 (28.7) 4665 (33.1)
Uncontrolled arterial hypertension, n (%) Isolated systolic 14,015 (28.4) 6201 (25.5) 3214 (29.5) 4600 (32.6)
Isolated diastolic 2610 (5.3) 1698 (7.0) 485 (4.5) 427 (3.0)
Combined systolic-diastolic 9643 (19.6) 6024 (24.8) 1759 (16.1) 1860 (13.2)
Resistant arterial hypertension 6326 (12.8) 2282 (9.4) 1464 (13.4) 2580 (18.3)

IQR: interquartile range

* Sex was missing for 2 patients, 1 with stage 2 arterial hypertension and 1 with stage 3 arterial hypertension.

** See definitions in appendix table S1.

Blood pressure control

The average index measurement was 139.9 mm Hg (SD 18.7) for systolic blood pressure and 81.9 mm Hg (SD 11.4) for diastolic blood pressure (systolic and diastolic blood pressure distributions are shown in figure S3–S4 in the appendix). Overall, blood pressure control was observed in 23,022 patients (46.7%), while the secondary blood pressure goal was met in 12,411 patients (25.2%). The percentages increased with the arterial hypertension stage, with blood pressure control rates of 42.7%, 49.9%, and 51.1%, and achievement of the secondary goal in 19.0%, 28.7%, and 33.1% of cases in arterial hypertension stages 1 to 3, respectively. Blood pressure control and the achievement of the secondary blood pressure goal, stratified by arterial hypertension stage and age group, are shown in table 1 and figure 1, respectively. 

Figure 1Blood pressure control (BPC) (defined as achieving systolic <140 mm Hg and diastolic <90 mm Hg) and achievement of the secondary blood pressure goal (systolic <130 mm Hg, or <140 mm Hg if aged ≥65 years, and diastolic <80 mm Hg). Percentages are reported overall and stratified by patient age group. BP: blood pressure.

Antihypertensive pharmacotherapy

Overall, 36,692 patients (74.4%) had active antihypertensive prescriptions at the time of the blood pressure index measurement. Among the remaining 12,598 patients (25.6%), 6092 (12.4%) had never been treated, and 6506 (13.2%) had previously been prescribed antihypertensive pharmacotherapy, which was later discontinued. Regarding treatment intensity, 12,820 patients (26.0%) were prescribed monotherapy, 11,937 (24.2%) were prescribed dual therapy, 7771 (15.8%) received triple therapy, and 4164 (8.4%) received more than three antihypertensive substances.

The most frequently prescribed drug class overall was ARB, prescribed to 17,102 patients (34.7%), followed by beta-blockers to 15,756 patients (32.0%), and ACEI to 14,956 patients (30.3%). The distribution of individual drug classes across monotherapy, dual therapy, triple therapy, and four or more therapies is shown in figure 2.

Figure 2Drug classes by intensity of prescribed pharmacotherapy. Percentages are stratified across patients receiving monotherapy, dual therapy, triple therapy, and four or more therapies. ACEI: angiotensin-converting enzyme inhibitor; ARB: angiotensin receptor blocker; BB: beta-blocking agent; CCB: calcium channel blocker; D: diuretic; O: other antihypertensives.

Table 2 describes the prescribed antihypertensive pharmacotherapies overall and stratified by blood pressure control status (ATC codes listed in table S4 in the appendix).

Table 2Numbers (percentages) of patients with (or without) specific antihypertensive pharmacotherapy at index measurement, overall and stratified by blood pressure control. Only drug combinations exceeding 1% within classes are shown.

  Overall Patients with BPC Patients without BPC
n = 49,290 n = 23,022 n = 26,268
Pharmacotherapy
Active* antihypertensive pharmacotherapy n (%) 36,692 (74.4) 17,483 (75.9) 19,209 (73.1)
No active antihypertensive pharmacotherapy n (%) 12,598 (25.6) 5539 (24.1) 7059 (26.9)
– Never prescribed 6092 (12.4) 2243 (9.7) 3849 (14.7)
– Prescribed but discontinued 6506 (13.2) 3296 (14.3) 3210 (12.2)
Type of antihypertensive pharmacotherapy
Monotherapy n (%) Overall 12,820 (26.0) 6181 (26.8) 6639 (25.3)
ACEI 3953 (8.0) 1793 (7.8) 2160 (8.2)
ARB 3399 (6.9) 1479 (6.4) 1920 (7.3)
Beta-blocker 3836 (7.8) 2174 (9.4) 1662 (6.3)
CCB 1453 (2.9) 650 (2.8) 803 (3.1)   
Diuretic 115 (0.2) 53 (0.2) 62 (0.2)
Dual therapy, n (%) Overall 11,937 (24.2) 5693 (24.7) 6244 (23.8) 
All fixed-dose combinations 5779 (11.7) 2615 (11.4) 3164 (12.0)
ARB + diuretic, total 2225 (4.5) 970 (4.2) 1255 (4.8)
… as fixed-dose combination 2144 (4.3) 944 (4.1) 1200 (4.6)
ARB + CCB, total 1791 (3.6) 760 (3.3) 1031 (3.9)
… as fixed-dose combination 942 (1.9) 412 (1.8) 530 (2.0)
ARB + beta-blocker, total 1298 (2.6) 645 (2.8) 653 (2.5)
… as fixed-dose combination
ACEI + CCB, total 1538 (3.1) 674 (2.9) 864 (3.3)
… as fixed-dose combination 678 (1.4) 309 (1.3) 369 (1.4)
ACEI + beta-blocker, total 1819 (3.7) 1081 (4.7) 738 (2.8)
… as fixed-dose combination
ACEI + diuretic, total 1607 (3.3) 733 (3.2) 874 (3.3)
… as fixed-dose combination 1560 (3.2) 709 (3.1) 851 (3.2)
CCB + beta-blocker, total 716 (1.5) 343 (1.5) 373 (1.4)
… as fixed-dose combination 50 (0.1) 27 (0.1) 23 (0.1)
Triple therapy n (%)   Overall 7771 (15.8) 3718 (16.1) 4053 (15.4)
As single drugs 2592 (5.3) 1281 (5.6) 1311 (5.0)
Including a dual fixed-dose combination 3968 (8.1) 1849 (8.0) 2119 (8.1)
As a triple fixed-dose combination 1211 (2.5) 588 (2.6) 623 (2.4)
ARB + CCB + diuretic, total 1930 (3.9) 846 (3.7) 1084 (4.1)
… including a dual fixed-dose combination 1010 (2.0) 420 (1.8) 590 (2.2)
… as triple fixed-dose combination 890 (1.8) 416 (1.8) 474 (1.8)
ARB + CCB + beta-blocker, total 992 (2.0) 456 (2.0) 536 (2.0)
… including a dual fixed-dose combination 404 (0.8) 180 (0.8) 224 (0.9)
… as triple fixed-dose combination
ARB + beta-blocker + diuretic, total 1024 (2.1) 500 (2.2) 524 (2.0)
… including a dual fixed-dose combination 977 (2.0) 480 (2.1) 497 (1.9)
… as triple fixed-dose combination
ACEI + CCB + diuretic, total 985 (2.0) 457 (2.0) 528 (2.0)
… including a dual fixed-dose combination 631 (1.3) 270 (1.2) 361 (1.4)
… as triple fixed-dose combination 321 (0.7) 172 (0.7) 149 (0.6)
ACEI + CCB + beta-blocker, total 865 (1.8) 453 (2.0) 412 (1.6)   
… including a dual fixed-dose combination 275 (0.6) 157 (0.7) 118 (0.4)
… as triple fixed-dose combination
ACEI + beta-blocker + diuretic, total 731 (1.5) 381 (1.7) 350 (1.3)
… including a dual fixed-dose combination 671 (1.4) 342 (1.5) 329 (1.3)
… as triple fixed-dose combination
Four or more therapies n (%) 4164 (8.4) 1891 (8.2) 2273 (8.7) 
Number of drugs median (IQR) 1 (0–2)  1 (1–2)  1 (0–2)

Abbreviations: ACEI, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker; CCB, calcium channel blocker; IQR, interquartile range.

*Active pharmacotherapy included all antihypertensive drugs documented but not subsequently discontinued in the 5 years preceding the index measurement.

The most frequently prescribed combinations in patients who received dual therapy were ARB + diuretic and ACEI + beta-blocker (prescribed to 4.5% and 3.7% of patients, respectively). The most prescribed triple therapies were ARB + CCB + diuretic (3.9%) and ARB + beta-blocker + diuretic (2.1%). Among patients on dual or triple antihypertensive therapies, 10,958 (22.2% of all patients) were prescribed fixed-dose combinations.

Factors associated with blood pressure control

The final adjusted regression model, shown in figure 3, revealed that blood pressure control was positively associated with arterial hypertension stage. Compared to stage 1 patients, stage 2 patients had an OR of 1.38 (CI 1.31–1.45), and stage 3 patients had an OR of 1.46 (CI 1.39–1.54). Other factors positively associated with blood pressure control included the intensity of blood pressure monitoring in 2021, with an OR of 1.35 (CI 1.23–1.48) for patients with more than five measurements compared to those with fewer. Treatment with blood pressure-increasing drugs was also positively associated with blood pressure control, with an OR of 1.06 (CI 1.01–1.12) for one blood pressure-increasing drug prescribed, and 1.14 (CI 1.06–1.23) for more than one blood pressure-increasing drug, compared to no blood pressure-increasing drugs. Conversely, blood pressure control was negatively associated with female sex (OR 0.86, CI 0.83–0.90) compared to male sex, patient age ≥65 years (OR 0.88, CI 0.84–0.91) compared to younger age, lack of antihypertensive pharmacotherapy (OR 0.86, CI 0.82–0.91) compared to being on antihypertensive pharmacotherapy, and a long-lasting diagnosis (OR 0.91, CI 0.86–0.96) compared to a diagnosis within the last five years. Further results are provided in table S5 in the appendix.

Figure 3Unadjusted (univariable) and multivariable (adjusted) logistic mixed regression model (forest plot) of blood pressure control. General practitioners (GPs) were considered as random effects. AH: arterial hypertension; BP: blood pressure; OR: odds ratio; CI: confidence interval.

Discussion

Main findings

In this study, we aimed to improve the understanding of blood pressure control and pharmacotherapy in patients with arterial hypertension treated in Swiss general practice. We found nearly half of the patients with blood pressure control, and one in four met the secondary blood pressure goal. Three-quarters of patients with arterial hypertension received antihypertensive pharmacotherapy, predominantly in the form of monotherapy or dual therapy. Blood pressure control was positively associated with arterial hypertension stage, the intensity of blood pressure monitoring, and the number of blood pressure-increasing drugs, but negatively associated with the absence of antihypertensive pharmacotherapy, long-standing arterial hypertension diagnosis, female sex, and older age.

Patient selection and sample representativeness

We identified patients with arterial hypertension from a large Swiss primary care database and found a prevalence of approximately 22%. This figure aligns closely with the prevalence reported by Godwin et al., who used highly comparable methods in a Canadian general practice-based study [25]. Another study estimated the prevalence of arterial hypertension in Swiss general practice to be 20% [26], supporting the validity of our data. The patients in our study were, on average, more than five years older than those in similar studies using routine general practice data [14, 25, 27]. This difference may be due to our study design. First, unlike Godwin et al., we did not impose an upper age limit. Second, our study required patients to have undergone blood pressure monitoring in 2021, which may have selected older patients requiring more intensive follow-up.

Risk-stratified strategy for blood pressure control

In our study, 74% of patients received pharmacotherapy for arterial hypertension, and nearly 50% achieved blood pressure control, a figure consistent with studies from other high-income Western countries [13] and a previous Swiss study [14]. We found a positive association between arterial hypertension stage and blood pressure control, suggesting a risk-stratified treatment strategy. This represents a shift from previous evidence from Swiss general practice in 2009, where a negative association was observed [14]. However, a risk-stratified approach was introduced in the 2013 ESC/ESH guidelines for arterial hypertension management and appears to have been adopted by Swiss general practitioners [28].

This risk-stratified approach was even more pronounced for the secondary blood pressure goal, with significant differences between groups: 19% of arterial hypertension stage 1 patients and 33% of arterial hypertension stage 3 patients achieved the secondary goal. However, it should be noted that the secondary goal is age-dependent, and arterial hypertension stage 3 patients, who were on average six years older, had a more attainable target. Nevertheless, the stage 3 group also had double the proportion of patients with resistant hypertension compared to the stage 1 group (18% vs 9%), indicating further pharmaceutical escalation in response to higher risk.

Paradoxically, patients receiving blood pressure-increasing drugs were more likely to have blood pressure control. However, for non-steroidal anti-inflammatory drugs, the most frequently prescribed blood pressure-increasing drugs, the effects on blood pressure control are controversial [29]. In our data, 86% of patients on blood pressure-increasing drugs also received antihypertensive pharmacotherapy, compared with 70% of those not on blood pressure-increasing drugs, potentially offsetting the blood pressure-increasing effects. Moreover, it is possible that general practitioners were aware of the risks and prescribed blood pressure-increasing drugs selectively to patients with relatively low blood pressure levels.

Intensive blood pressure monitoring was also positively associated with blood pressure control, consistent with findings from previous studies that showed the benefits of monitoring interventions on blood pressure control [30–33].

Factors negatively associated with blood pressure control

Other findings warrant attention and could inform future quality improvement efforts. First, patients with long-standing arterial hypertension were less likely to have blood pressure control. This may indicate treatment inertia or status quo bias, which can result in a reluctance to adjust treatment over time [34, 35]. Furthermore, long-standing arterial hypertension leads to vascular remodelling, making it more challenging to treat [36]. Second, we found that female patients were less likely than male patients to have blood pressure control. This could be partly due to the higher proportion of older women in our study, as hypertensive women tend to have stiffer large arteries and consequently higher blood pressure than older men [37]. Although hypertension treatment and blood pressure control are generally less common in men than in women in most countries, this difference is small in high-income countries, and, in line with our findings, a reverse pattern is observed in a few countries [13, 38]. This issue requires further investigation and targeted quality initiatives, especially if unwarranted underuse of guideline-recommended therapy in female patients is contributing to this disparity [39]. Third, older patients were less likely to have blood pressure control. This finding is consistent with previous studies [40] and may be attributed to vascular ageing, degenerative processes [37], or reduced tolerability of antihypertensive pharmacotherapy in older patients. Additionally, general practitioners may be more reluctant to initiate or intensify treatment in older patients. However, the negative association between age and blood pressure control was significant only after adjusting for other potential confounders, suggesting that age alone is not a strong predictor of blood pressure control. Importantly, for patients aged ≥80 years, the risk-benefit ratio of antihypertensive pharmacotherapy remains unclear, but age alone should not justify treatment de-intensification [9, 10].

Finally, although the negative association between general practitioner age and blood pressure control was statistically significant, its relevance was limited. This is a novel finding that requires further research, though it may be explained by the higher proportion of older patients cared for by older general practitioners in our study.

Pharmacotherapy

Regarding pharmacotherapy, our findings were consistent with those of the SWISSHYPE study [14], which examined general practice patients receiving treatment for arterial hypertension in 2009: approximately one-third of patients received monotherapy, one-quarter received dual therapy, one-fifth were on triple therapy, and one-fifth received a fixed-dose combination. Both low adherence to medication and a “sequential monotherapy” treatment strategy may impede blood pressure control [10]. Most patients in randomised controlled arterial hypertension trials ultimately required combination therapy to control their blood pressure [41], and the PATHWAY study found that initial combination therapy resulted in higher blood pressure control rates than sequential monotherapy [42], likely due to the synergistic effects of different pharmacological mechanisms. Moreover, a recent meta-analysis found that single-pill combination therapy was superior to free-equivalent combination therapy in terms of drug adherence, persistence, and blood pressure control [43]. Increasing the use of fixed-dose combinations is therefore a promising strategy to improve blood pressure control, as recommended by the new ESC guidelines [44]. Nonetheless, in our study, fixed-dose combinations were used in only approximately 30% of treated patients. However, the availability of dual and triple-fixed-dose antihypertensive combinations is steadily increasing, which may increase the proportion of combination therapies.

The prevalence of beta-blocker prescriptions as monotherapy was higher than in the SWISSHYPE study [14]. Since treatment with beta-blockers is recommended for arterial hypertension treatment only under specific conditions [44], our findings suggest a gap between guidelines and practice in the management of arterial hypertension that requires further investigation.

Strengths and limitations

The strengths of this study include its size and representativeness, as it draws on the large FIRE database [45]. Furthermore, we identified patients with arterial hypertension not only through diagnostic codes and pharmacotherapy but also by including blood pressure measurements. This approach provided valuable insights into the management of patients, including those who did not receive pharmacotherapy, and allowed us to study different blood pressure goals. Our approach to identifying patients based on electronic records is highly reproducible and can be utilised in follow-up studies and interventional studies aimed at improving the quality of care at the general practitioner level. A further strength of this study is its novel consideration of both patient and general practitioner characteristics as potential factors associated with blood pressure control.

The main limitation of this study is the potential for misclassification. Firstly, although there are established guidelines for measuring blood pressure [46], we cannot confirm that a standardised measurement protocol was always followed. However, it is highly likely that most blood pressure measurements in the electronic medical records were office-based readings, which can detect “white coat hypertension” in up to 24% of cases [47, 48]. This “white coat hypertension” can be reproduced in about half of patients after a single measurement [49], and since 11% of patients in our sample were identified solely by blood pressure measurement, up to 5% may have been misclassified as having arterial hypertension, potentially biasing the blood pressure control rate towards a lower proportion. Secondly, false-positive identification based on pharmacotherapy cannot be ruled out, especially in cases where antihypertensive drugs were prescribed primarily for other cardiovascular indications, such as heart disease. However, since most cases of heart disease are associated with arterial hypertension (even if not formally diagnosed), this may be of limited concern. Thirdly, we used arterial hypertension staging criteria according to the 2018 ESC/ESH guidelines [10], but without access to information on hypertension-mediated organ damage, which was unavailable in our database. This may have led to an overestimation of the number of stage 1 patients at the expense of stage 2 patients. However, given that cardiovascular disease is likely to be accurately detected in our database, the main results of our study are unlikely to be affected by this limitation.

Fourthly, we acknowledge that about half of the patients with arterial hypertension were excluded because they did not have any blood pressure measurements in 2021. This could affect the validity of our results concerning blood pressure control, as blood pressure control is contingent upon blood pressure measurements being recorded.

Another limitation is the study design, which did not allow for the investigation of causality, only associations with blood pressure control. Moreover, we lacked information on several factors that could have influenced blood pressure control, such as patient awareness of arterial hypertension, lifestyle (diet, physical activity, stress), socio-economic and educational status, non-pharmacological treatment, or compliance with pharmacotherapy [44, 50].

Conclusions

Our findings suggest that general practitioners are adopting a risk-stratified management strategy for patients with arterial hypertension, in line with the revised guidelines. This represents a paradigm shift compared to the management strategies employed a decade ago. However, uncontrolled arterial hypertension remains prevalent in Swiss general practice, and there is significant potential to improve the quality of care, particularly for patients not receiving arterial hypertension pharmacotherapy, those with long-standing arterial hypertension, female sex or old age. The results of this study may inform policymakers and health professionals in designing interventions to enhance blood pressure control.

Open science

An unpublished research protocol was used to guide the study. Data supporting the results are not publicly available due to institutional data protection restrictions but can be obtained from the corresponding author upon reasonable request, along with the R-script used for the statistical analysis.

Notes

This research was funded by an unrestricted research grant from Servier Pharmaceuticals.

All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. RB has received speaker fees from Servier Pharmaceuticals. The other authors did not disclose individual conflicts of interest related to the content of this manuscript.

Stefania Di Gangi

Institute for Primary Care

University Hospital Zurich

Pestalozzistrasse 24

CH-8091 Zurich

stefania.digangi[at]usz.ch

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Appendix

The appendix is available in the pdf version of the article at https://doi.org/10.57187/s.3898.