October 29th, 2013
A Comparative Effectiveness Research (CER) study shows that surgery is better than medical treatment for a particular cardiac condition. My patient is 78 years old and has complicated diabetes. – does the study apply? Another patient 48 years old and otherwise healthy. Does it apply here?
Can the overall results of a CER study be applied to all patients in the target population? Are there substantial, undetected variations among patients in the results of CER? What is the extent of exceptions? These are important policy questions in applying results of CER to day-to-day decisions, clinical guidelines, performance measures and other facets of the modern healthcare system.
The “gold standard” approach to CER is the randomized (RCT), a scientific comparison of two or more clinical strategies, with the downsides that it is generally conducted in a special environment and usually has a rather narrow (and possibly unrepresentative) population spectrum. Two variants, the Practical (or Pragmatic) Clinical Trial (PCT) and the Large Simple Trial (LST) are inclusive of a wider spectrum of patients and more diverse clinical settings.
These approaches provide “average” results and for the most part it is thought that averages do apply to a large segment of the population at large for which they are intended. However, there are clearly differences in effect (heterogeneities of treatment effect – HTE’s) that manifest among CER study subjects and presumably to a greater extent in the intended population outside the study. Two approaches may be equivalent on the average but one may be better in a particular group, and differences may be less apparent when the study’s population base is narrow. A long list of factors contribute to these HTEs for CER and other trials – comorbidities, severity of illness, genetics, age, medication adherence, susceptibility to adverse events, ethnicity, site, economics and others.Read the rest of this entry »