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Original article

Vol. 145 No. 4344 (2015)

A low observed-to-expected postoperative mortality ratio in a Swiss high-standard peri-operative care environment – an observational study

  • Nadine Wickboldt
  • Guy Haller
  • Cecile Delhumeau
  • Bernhard Walder
DOI
https://doi.org/10.4414/smw.2015.14205
Cite this as:
Swiss Med Wkly. 2015;145:w14205
Published
18.10.2015

Summary

QUESTIONS UNDER STUDY/PRINCIPLES: The objective was to assess observed-to-expected in-hospital postoperative 30-day mortality and to identify associated risks.

METHODS: A single centre, retrospective study was performed in Geneva University Hospitals, Switzerland. Hospitalised adult surgical patients who received anaesthesia and stayed in the Post Anaesthesia Care Unit – Intermediate Care Unit (PACU-IMC) between July 2008 and June 2011 were included. Outcome measure was in-hospital 30-day mortality. Expected probabilities of in-hospital death were estimated with the surgical mortality probability model (S-MPM). Descriptive statistics were calculated. Univariate and multivariate logistic regressions (odds ratio [OR] with 95% confidence interval [95% CI]) were used to identify risk factors of mortality.

RESULTS: Overall in-hospital mortality was 0.8% (176/24 160 patients). Observed 30-day in-hospital mortality was 0.7%; expected mortality from the S-MPM was 1.2%. Independent risk factors were age (OR 1.05, 95% CI 1.03–1.06), American Society of Anesthesiologists Physical Status score (ASA PS 3–5 vs ASA PS 1-2: OR 5.48, 95% CI 3.12–9.63), nonelective surgery (vs elective surgery) (OR 3.15, 95% CI 2.04–4.86), head  surgery (OR 2.83, 95% CI 1.41–5.67) and duration of PACU-IMC stay (OR 1.00, 95% CI 1.00–1.00). A protective factor was a high body mass index (OR 0.92, 95% CI 0.89–0.96). The procedural risk, type and time of anaesthesia and day of intervention were not independent risk factors of mortality.

CONCLUSION: The postoperative observed-to-expected mortality ratio was favourable. Independent postoperative risk factors for mortality were well-established factors such as age, ASA PS, non elective surgery but also duration of PACU-IMC stay which was considered as a surrogate of postoperative complications.

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