Quantification of the External Validity of Randomized Controlled Trials Supporting Clinical Care Guidelines: The Case of Thromboprophylaxis

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 randomized 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 1, 2013 and June 30, 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 randomized 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 years (interquartile ratio 51-77 years), 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 randomized 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 randomized 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.

Interprofessional meetings in geriatric assessment units: a matter of care organization

Inpatient geriatric assessment units (GAUs) exist in Quebec, Canada, to deliver comprehensive, integrated care to older vulnerable patients. Most cases should be discussed at interprofessional meetings (IMs), but research has shown this not to be so for 39% of GAU patients. Consequently, a study was undertaken to (1) describe GAU team composition and (2) identify GAU and patient characteristics associated with case discussion at IMs at least once during a patient's stay. To this end, 877 hospitalization records from 44 GAUs were reviewed. Results showed most teams were composed of attending physicians, nurses, physical and occupational therapists, dietitians and social workers; 66% included clinical pharmacists and 43% liaison nurses. Multilevel modeling showed longer length of stay to be the strongest predictor of case discussion at an IM. Case discussion was also more likely for patients admitted via in- or inter-hospital transfer rather than via the emergency department, if the GAU included a liaison nurse, and if the GAU was not located in an urban area. In summary, case discussion at an IM depended more on how and where a patient was admitted than on the patient characteristics per se, suggesting that this is a matter of care organization.