Systematic reviews of randomised controlled trials provide an evidence base for treatment but too often fail to give adequate information on long term outcomes, which are important for people with chronic diseases. Elphick and colleagues (p 381) discuss the limitations of systematic reviews of randomised controlled trials for patients with chronic diseases and maintain that long term observational studies have a place in evaluating the benefits and risks of treatment.
. 2002 Aug 17;325(7360):0.