- Donald A Redelmeier, professor of medicine1234,
- Finlay A McAlister, professor5,
- Christopher E Kandel, medical student1,
- Hong Lu, statistical analyst3,
- Nick Daneman, assistant professor123
- 1Department of Medicine, University of Toronto, Toronto, Canada
- 2Clinical Epidemiology Program, Sunnybrook Health Sciences Centre, Ontario, Canada
- 3Institute for Clinical Evaluative Sciences in Ontario, Ontario, Canada
- 4Patient Safety Service, Sunnybrook Health Sciences Centre
- 5Department of Medicine, University of Alberta, Edmonton, Canada
- Correspondence to: D A Redelmeier, Sunnybrook Health Sciences Centre, G-151, 2075 Bayview Ave, Ontario, Canada M4N 3M5
- Accepted 25 March 2010
Objective To test whether gastric acid suppressants are associated with an increased risk of postoperative pneumonia in patients undergoing elective surgery.
Design Population-wide retrospective cohort analysis.
Setting Canadian acute care hospitals between 1 April 1992 and 31 March 2008.
Patients Consecutive patients aged >65 years admitted for an elective operation.
Outcome measure Postoperative pneumonia recorded in inpatient postoperative notes.
Results A total of 593 265 patients were included, of whom about 21% were taking an acid suppressant (most commonly omeprazole or ranitidine). Overall, 6389 patients developed postoperative pneumonia, with a rate significantly higher for those taking acid suppressants (13 per 1000) than controls (10 per 1000), equivalent to a 30% increase in frequency (odds ratio 1.30 (95% confidence interval 1.23 to 1.38), P<0.001). However, no increase in risk was observed after adjustment for duration of surgery, site of surgery, and other confounders (odds ratio 1.02 (0.96 to 1.09), P=0.48). The general safety of acid suppressants extended to those patients prescribed proton pump inhibitors, experiencing long term treatment, receiving high doses, and undergoing high risk procedures.
Conclusion After adjustment for patient and surgical characteristics, acid suppressants are not associated with an increased risk of postoperative pneumonia among elderly patients admitted for elective surgery.
Contributors: We thank Daniel Hackam, David Juurlink, Gabor Kandel, Muhammad Mamdani, Matthew Stanbrook, Damon Scales, Steven Shumak, and Arthur Slutsky for helpful comments on earlier drafts of this article. All authors contributed to the design of the study, interpretation of results, and manuscript preparation. Both DAR and HL were responsible for checking all computer programming and computer output. All authors except HL were responsible for literature review and bibliography construction. DAR is guarantor and accepts full responsibility for the work, conduct of the study, access to the data, and decision to publish.
Funding: This project was supported by the Canada Research Chair in Medical Decision Sciences, a Military Health Services Research grant from the Canadian Forces Health Services, the Physicians Services Incorporated Foundation of Ontario, the Alberta Heritage Foundation for Medical Research, and the University of Toronto Comprehensive Research Experience for Medical Students programme. The funding organisations had no role in the design and conduct of the study; collection, management, analysis, and interpretation of data; and preparation, review, or approval of the manuscript. The views expressed in this paper are those of the authors and do not necessarily reflect the Ontario Ministry of Health.
Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from DAR) and declare that all authors had: (1) no financial support for the submitted work from anyone other than their employer; (2) no financial relationships with commercial entities that might have an interest in the submitted work; (3) no spouses, partners, or children with relationships with commercial entities that might have an interest in the submitted work; (4) no non-financial interests that may be relevant to the submitted work.
Data sharing: No additional data available.
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