Capturing health care utilization after occupational low-back pain: Development of an interviewer-administered questionnaire

The aim of this study was to develop and test the feasibility and validity of a patient questionnaire to assess health care utilization after occupati onal low-back pain (LBP). Items generated after a literature search were re vised and refined on the basis of their face and content validity (judged b y a group of practitioners) and pretested with six lay subjects who had LBP . The 73-item questionnaire was then tested in interviews with subjects wit h acute, subacute, or chronic LBP. Its validity was judged by comparison wi th a prospective patient diary and with care-provider reports. Chance-corre cted agreement was estimated using the kappa statistic. Response rates were 78%, 70%, and 59% for interview, diary, and provider reports, respectively . Eighty of 102 eligible workers completed the interview in an average of 4 5 minutes (SD = 17.7). Most LBP subjects (90.1%) found it easy to answer. I n the opinion of the interviewer, 94.7% of subjects showed adequate compreh ension and ability to recall. With a few exceptions, there was moderate to substantial agreement between the interview and the patient diary (most kap pa values between 0.38 and 0.78). Overall, subjects reported more health ca re services to the interviewer than they recorded in the diary. Owing to th e low response rate from providers, comparison with provider reports had to be restricted to 48 subjects and to physicians' reports only. Agreement be tween interviews and physicians' reports was substantial in use of plain X- rays (kappa = 0.79) and computed tomography scans (kappa = 0.85), but physi cians often reported referrals nor. volunteered by the subjects. Agreement on prescription medications was fair (kappa = 0.29-0.46) with no systematic over reporting or under reporting. Our interviewer-administered questionna ire had better return rate than the patient diary and provider reports. It was easy to administer and understand. On the basis of our comparison with patient diaries and physicians' reports, we conclude that this questionnair e is a sufficiently valid source of health care utilization data in subject s with LBP. J CLIN EPIDEMOL 52;5:419-427, 1999. (C) 1999 Elsevier Science I nc.