Clinical review Observational studies as alternatives randomized clinical trials in surgical clinical research

CLINICAL EPIDEMIOLOGY AS A DISCIPLINE has evolved rapidly dur ing the last decade. However, application of epidemiotogic principles in surgical clinical research has been limited. In the March 1996 issue of SURGERY we discussed the principles, application, and limitations of randomized clinical trials (RCTs) in surgery. RCTs are often viewed as the gold standard for evaluation of therapeutic efficacy because they are the closest that clinical medicine can come to the controlled environmen t of laboratory research. However, clinical decisions often have to be made in the absence of data obtained this way. In this issue we will discuss some alternatives that can be used in surgical clinical research. Alternatives to RCTs fall into the purview of observational epidemiology, which can be grouped into five major categories: case reports, case series, cross-sectional studies, case-control studies, and cohort studies. The former three are often referred to as descriptive studies, and the remaining two are labeled as analytic or comparative studies.