The penumbra of randomized control trials.

Pre-occupation with randomized control trials as the basis of evidence-based medicine has increasingly shadowed other study designs over the last half a century. These include surveys, case-control studies, and case-cohort studies. They have the potential to overcome several ethical and cost constraints, but depend on the embedding of research in routine practice, emphasis on relevant but limited, accurate, and complete data, harnessing of information technology for this purpose, and epidemiological and statistical literacy among clinicians. Only then will it be possible to nurture and network research-oriented practices by therapeutic areas. Given these, the alternative study designs can pave the way to regulatory reforms that will ultimately benefit the discoverers, approvers and users of health-care tools.