The work limitations questionnaire

OBJECTIVE. The objective of this work was to develop a psychometrically sou nd questionnaire for measuring the on-the-job impact of chronic health prob lems and/or treatment ("work limitations"). RESEARCH DESIGN. Three pilot studies (focus groups, cognitive interviews, a nd an alternate forms test) generated candidate items, dimensions, and resp onse scales. Two field trials tested the psychometric performance of the qu estionnaire (studies 1 and 2). To test recall error, study 1 subjects were randomly assigned to 2 different questionnaire groups, a questionnaire with a 4-week reporting period completed once or a 2-week version completed twi ce. Responses were compared with data from concurrent work limitation diari es (the gold standard). To test construct validity, we compared questionnai re scores of patients with those of healthy job-matched control subjects. S tudy 2 was a cross-sectional mail survey testing scale reliability and cons truct validity. SUBJECTS. The study subjects were employed individuals (18-64 years of age) from several chronic condition groups (study I, n = 48; study 2, n = 121) and, in study 1, 17 healthy matched control subjects. MEASURES. Study I included the assigned questionnaires and weekly diaries. Study 2 included the new questionnaire, SF-36, and work productivity loss i tems. RESULTS. In study 1, questionnaire responses were consistent with diary dat a but were most highly correlated with the most recent week. Patients had s ignificantly higher (worse) limitation scores than control subjects. In stu dy 2,4 scales from a 25-item questionnaire achieved Cronbach alphas of grea ter than or equal to0.90 and correlated with health status and self-reporte d work productivity in the hypothesized manner (P less than or equal to0.05 ). CONCLUSIONS. With 25 items, 4 dimensions (limitations handling time, physic al, mental-interpersonal, and output demands), and a 2-week reporting perio d, the Work Limitations Questionnaire demonstrated high reliability and val idity.