Inadequate statistical power of published comparative cohort studies on ventilator-associated pneumonia to detect mortality differences

Falagas, ME; Kouranos, VD; Michalopoulos, A; Rodopoulou, SP; Athanasoulia, AP; Karageorgopoulos, DE

dc.contributor.author	Falagas, ME	en
dc.contributor.author	Kouranos, VD	en
dc.contributor.author	Michalopoulos, A	en
dc.contributor.author	Rodopoulou, SP	en
dc.contributor.author	Athanasoulia, AP	en
dc.contributor.author	Karageorgopoulos, DE	en
dc.date.accessioned	2014-03-01T01:33:38Z
dc.date.available	2014-03-01T01:33:38Z
dc.date.issued	2010	en
dc.identifier.issn	1058-4838	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/20504
dc.subject.classification	Immunology	en
dc.subject.classification	Industrial Relations & Labor	en
dc.subject.classification	Infectious Diseases	en
dc.subject.classification	Microbiology	en
dc.subject.other	article	en
dc.subject.other	cohort analysis	en
dc.subject.other	comparative study	en
dc.subject.other	human	en
dc.subject.other	mortality	en
dc.subject.other	priority journal	en
dc.subject.other	publication	en
dc.subject.other	risk assessment	en
dc.subject.other	statistical significance	en
dc.subject.other	uncertainty	en
dc.subject.other	ventilator associated pneumonia	en
dc.subject.other	Cohort Studies	en
dc.subject.other	Data Interpretation, Statistical	en
dc.subject.other	Humans	en
dc.subject.other	Pneumonia, Ventilator-Associated	en
dc.title	Inadequate statistical power of published comparative cohort studies on ventilator-associated pneumonia to detect mortality differences	en
heal.type	journalArticle	en
heal.identifier.primary	10.1086/649929	en
heal.identifier.secondary	http://dx.doi.org/10.1086/649929	en
heal.language	English	en
heal.publicationDate	2010	en
heal.abstract	Background. Comparative cohort studies are often conducted to identify novel therapeutic strategies or prognostic factors for ventilator-associated pneumonia (VAP). We aimed to evaluate the power of such studies to provide clinically and statistically significant conclusions with regard to mortality differences. Methods. We searched in PubMed and Scopus for comparative cohort studies that evaluated mortality in patients with VAP. We calculated the central estimates and corresponding 95% confidence intervals (CIs) for mortality differences between compared patient groups. We also calculated the statistical power of the included studies to detect a difference in mortality that corresponds to a risk ratio of 0.80. Results. We identified 39 (20 prospective) comparative cohort studies on VAP as eligible for inclusion in this analysis. The median absolute risk difference in mortality between compared groups was 10% (interquartile range [IQR], 5%-18%), and the median width of the 95% CI of the absolute risk difference in mortality was 34% (IQR, 28%-42.5%). The median power of the included studies to detect a risk ratio for mortality of 0.80 was 14.7% (IQR, 10.696-21.8%). Conclusions. There is considerable uncertainty around the central estimate of comparative cohort studies on VAP with regard to mortality differences. For a wiser use of resources allocated to research, we emphasize the need to conduct cohort studies with larger sample size so that potential differences between the compared groups are more likely to be shown. © 2010 by the Infectious Diseases Society of America. All rights reserved.	en
heal.publisher	UNIV CHICAGO PRESS	en
heal.journalName	Clinical Infectious Diseases	en
dc.identifier.doi	10.1086/649929	en
dc.identifier.isi	ISI:000273846400007	en
dc.identifier.volume	50	en
dc.identifier.issue	4	en
dc.identifier.spage	468	en
dc.identifier.epage	472	en