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"Quantification of the External Validity of Randomized Controlled Trials Supporting Clinical Care Guidelines: the Case of Thromboprophylaxis."
Am J Med. 2016 Mar 8;
Authors: Morin-Ben Abdallah S, Dutilleul A, Nadon V, Yang J, Marchand-Sénécal X, Van Nguyen P, Lamarre-Cliche M, Wistaff R, Kolan C, Laskine M, Durand M
Abstract
BACKGROUND: Clinical guidelines are based on the results of several randomized controlled trials. However, due to the stringent exclusion criteria of these trials, their external validity may be low. We aimed to evaluate the external validity of the randomised controlled trials cited in the American College of Chest Physicians guidelines for the use of pharmacological thromboprophylaxis in hospitalized medical patients.
METHODS: We conducted a cross sectional, chart-review study of a random sample of patients admitted between July 1st 2013 and June 30th 2014 to the Internal Medicine ward of a large Canadian teaching university hospital. We identified the proportion of our population presenting exclusion criteria used in the randomised controlled trials cited in support of clinical care guidelines on thromboprophylaxis in the medical setting.
RESULTS: Nine trials were identified for a total of 28,793 included patients following 23 distinct exclusion criteria. We included 429 patients. Median age was 65(IQR 51-77) and 236(55%) were males. Of those not already anticoagulated at admission (n=351), between 26% and 67%(weighted average 51%) of our population presented at least one exclusion criterion, making them ineligible to be enrolled in randomised controlled trials. When restricting our population to patients with an indication for thromboprophylaxis based on a Padua risk score at admission ≥4, 21% to 76%(weighted average 55%) were ineligible to be enrolled in individual trials.
CONCLUSIONS: Our cross sectional study illustrates that the external validity of randomised controlled trials cited in the guidelines was low in our population, and lower when applying the risk stratification tool recommended by guidelines. This can bias the clinicians toward treating patients that were not represented in the supporting evidence.
PMID: 26968472 [PubMed - as supplied by publisher]