SF 36 health survey questionnaire: II. Responsiveness to changes in health status in four common clinical conditions.

OBJECTIVE To assess the responsiveness of the SF 36 health survey questionnaire to changes in health status over time for four common clinical conditions. DESIGN Postal questionnaires at baseline and after one year's follow up, with two reminders at two week intervals if necessary. SETTING Clinics and four training general practices in Grampian region in the north east of Scotland. PATIENTS More than 1,700 patients aged 16 to 86 years with one of four conditions: low back pain, menorrhagia, suspected peptic ulcer, and varicose veins; and a random sample of 900 members of the local general population for comparison. MAIN MEASURES A transition question measuring change in health and the eight scales of the SF 36 health survey questionnaire; standardised response means (mean change in score for a scale divided by the standard deviation of the change in scores) used to quantify the instrument's responsiveness to changes in perceived health status, and comparison of patient scores at baseline and follow up with those of the general population. RESULTS The response rate exceeded 75% in a patient population. Changes across the SF 36 questionnaire were associated with self reported changes in health, as measured by the transition question. The questionnaire showed significant improvements in health status for all four clinical conditions, whether in referred or non-referred patients. For patients with suspected peptic ulcer and varicose veins the SF 36 profiles at one year approximate to the general population. CONCLUSIONS These results provide the first evidence of the responsiveness of the SF 36 questionnaire to changes in perceived health status in a patient population in the United Kingdom.