COMPARISON OF RESPONSES TO SF-36 HEALTH SURVEY QUESTIONS WITH ONE-WEEK AND 4-WEEK RECALL PERIODS

Objective. To compare the measurement properties of acute (one-week re call) and standard (four-week recall) versions of SF-36 Health Survey (SF-36) scale scores. Data Sources. SF-36 data collected from 142 part icipants (60% female, average age 39) in a clinical trial of an asthma medication: 74 patients randomized to the acute form and 68 to the st andard. Data Collection. The SF-36 was self-administered at the time o f a clinic visit (before clinical examination) to synchronize with cli nical measures of disease severity at three different time points duri ng the clinical trial: -2 weeks (two weeks before randomization to tre atment), baseline (week 0 or randomization), and +4 weeks (four weeks after baseline). Principal Findings. The acute form yielded high-quali ty data; scales conformed to the assumptions of the summated ratings m ethod used to score the standard SF-36; and scales had good distributi onal properties, were reliable, and had a factor content similar to th e standard. The data indicated that while the acute form was more sens itive than the standard to change in health status associated with cha nges in acute symptoms, acute scale scores may not be comparable to na tional norms based on the standard, particularly for those scales that assess frequency of health events during a specified time period. Con clusions. Results support the use of the acute form in its intended ap plications; however, further research is required to document the gene ralizability of greater sensitivity of the acute form to recent change s in health and to explore whether norms based on the standard can be used to interpret the acute scale scores.