Observational research in the evidence based environment: eclipsed by the randomised controlled trial?

Patient based measures of outcome are assuming an increasing importance in the evaluation of therapeutic intervention. A classic, theoretical example of the importance of this approach involves the reporting of trials evaluating surgical procedures for benign prostatic obstruction. High quality studies might report significant improvements in appropriate outcome measures, such as the urinary flow rate or frequency of nocturia, and establish an apparent superiority over conservative treatment. When, however, patient satisfaction is considered, a side effect of erectile impotence in the surgical group may reverse this position. A number of instruments have been developed for the quantitative assessment of what is now often referred to as “quality of life”. These may be generic, examining several aspects or dimensions of physical function and perceived well being. Others are disease specific with, for example, the Seattle Angina Questionnaire and the Cardiac Health Profile representing leading instruments in the assessment of angina pectoris.