Generalizing results of randomized trials to clinical practice: reliability and cautions

Abstract

Complex therapies need careful consideration before they can be applied routinely from trials into practice, and applying results from one health care environment to a different one should be carried out with caution. Generalizing results from well conducted trials to clinical practice can mostly be carried out with confidence, especially for simple therapies with good evidence of benefit.

Editorial: Vertebral compression fractures

“…The process of extrapolating clinical research data to clinical practice relies on a critical evaluation of the generalizability of the results presented. 6,18,22,30,31,34 Despite their status as the gold standard of clinical research, RCTs are often a form of "test tube" medicine. The restrictions and circumstances present in the study protocol and participating institutions rarely match the heterogeneity and characteristics of "real-life" practice.…”

“…The restrictions and circumstances present in the study protocol and participating institutions rarely match the heterogeneity and characteristics of "real-life" practice. 1,18,34 Generalizing results from RCTs requires a deep understanding of the tightly controlled conditions of the trial and the often unique characteristics of the patients enrolled. The results of single-center trials such as that of Farrokhi et al 17 (and in essence Buchbinder et al…”

“…10,12,25 However, as mentioned already, patients enrolling in RCTs are at best a selected subgroup and at worst a completely misrepresentative sample of the population at large with the disease of interest. 18,20 These population differences often result in differences in how interventions perform when implemented in general practice than when subjected to rigorous clinical trial. Not infrequently, treatment effects are larger or more beneficial in practice than they are in the tight confines of an RCT.…”

“…3,7,18 Biases on the part of both investigators and patients may alter the estimated effect of the intervention on outcomes, particularly when the outcome measure is something as subjective as pain.…”

“…Multi-center trials with large patient enrollment mitigate these threats to external validity, but even in the best of circumstances, the characteristics of patients willing to enroll in RCTs are known to be different from those in the general population, often with respect to disease severity and treatment preferences. 1,3,7,18,19,34 The practicing clinician, therefore, has to interpret the results of RCTs within the context of his or her own practice setting and population.…”