Early prediction of chronic disability after occupational low back injury

Study Design. An inception cohort design was used to study a consecutive sampl Objective. To refine and to test the Vermont Disability Prediction Questionnaire's ability to indicate an individual's relative risk for chronic disability after occupational low back injury. Summary of Background Data. Although most back-injured workers return to work quickly, the minority who do not account for the majority of associated costs and health care. Early identification of workers at high risk for disability would facilitate intervention strategies. Methods. During the study recruitment period, people aged 18-60 years reporting occupational low back injury to the Vermont Department of Labor and Industry within 11 days of onset were eligible. A Vermont Disability Prediction Questionnaire was mailed to the 442 subjects who could be contacted and who gave informed consent. One hundred sixty-three of the 166 subjects who completed and returned the questionnaire within 15 days of initial injury were telephoned 3 months later to determine work status. Those who returned the questionnaire were compared with those who would not consent or did not return the questionnaire in time according to age, sex, residence, wages, work hours per week, and length of employment. Employment status (inability to work because of low back pain) was evaluated by telephone interview 3 months after initial injury. Results. The follow-up interviewer was blinded to the Vermont Disability Prediction Questionnaire scores. Of the 163 subjects, 16 (10%) were not working because of low back pain. Using a simple dichotomous scoring system for 11 questionnaire items, a cut-off score of 0.48 identified 3-month postinjury work status, with 0.94 sensitivity and 0.84 specificity. Conclusion. The Vermont Disability Prediction Questionnaire is a brief, easily administered and scored tool for identifying back-injured workers at relative risk for chronic disability. Such early identification should increase the efficiency of disability prevention strategies by directing them toward people who need them most. The accuracy of the questionnaire needs to be tested in a variety of different clinical and socioeconomic settings.