Outcome measures for studying patients with low back pain.

There is growing recognition in the treatment of back pain that patient perspectives are essential in judging the results of treatment. Improving the patient's "quality of life" is often the main goal of therapy. Thus, although clinical research in the past has focused on physiologic outcomes, such as range of motion, muscle strength, or neurologic deficits, increasing attention is being given to the rigorous measurement of symptoms, functional status, role function, satisfaction with treatment, and health care costs. In many cases, these so-called "soft" outcomes can be measured with a level of reproducibility similar to more conventional clinical data such as imaging test results. Because symptoms and functional outcomes are sometimes only loosely associated with physiologic phenomena, the former outcomes should be measured directly. Modern questionnaires for measuring patient quality of life combine the expertise of social scientists and clinicians and have demonstrated validity. Furthermore, they have some important advantages over simple ratings of "excellent, good, fair, and poor" outcomes, or work status alone. Several modern instruments for measuring health-related quality of life in patients with low back pain are reviewed briefly, describing their content and length. Wider use of these instruments would help to increase clinician familiarity with their meaning and avoid duplication of effort in questionnaire development.