JAMA   
May 18, 2011, Vol 305, No. 19, pp 1937-2024
http://jama.ama-assn.org/current.dtl

Commentaries
From Efficacy to Effectiveness in the Face of Uncertainty: Indication Creep and Prevention Creep
Benjamin Djulbegovic, Ash Paul
JAMA. 2011;305(19):2005-2006.doi:10.1001/jama.2011.650

Extract
Therapeutic and prevention clinical research is typically performed to address questions of efficacy (“Can intervention work in the ideal study setting?”), effectiveness (“Does it work, generalized to real-world settings and applied to individual patients?”), and cost-effectiveness (“Is it worth it and should it be paid for?”). To date, both public and private research enterprise has predominantly funded efficacy research. Comparative effectiveness research holds promise to generate much-needed effectiveness data. However, given the large number of important clinical questions, it will not be possible to provide reliable empirical efficacy, effectiveness, and cost-effectiveness data for every question to help guide individual decision-making. 1 Instead, practitioners will continue to rely on inductive reasoning to apply the results of the study (“group averages” from an efficacy trial) to individual patients who often differ in important ways from patients enrolled in the efficacy trial (eg, these patients may be older, have comorbid conditions, or might …