Reliability and content validity of the Disability Assessment Structured Interview (DASI): A tool to assess functional limitations in claimants

Objective The aim of this study is to investigate the reliability and validity of the Disability Assessment Structured Interview (DASI). The DASI is a semi-structured interview for assessing long-term functional limitations concerning the work disability assessment of claimants. Methods A randomized controlled trial was conducted. Patients applying for a work-disability pension after 21 months of sick leave were independently interviewed and examined either by two physicians who had completed a DASI training period (n = 32) or by two physicians from a control group (n = 30) without any DASI training. Agreement percentages within both groups of physicians, eligibility for a disability benefit, and differences between the groups in terms of the scores given on the work-limitation items from the Functional Ability List (FAL) were measured to investigate reliability and concurrent validity. To determine the content validity, the insurance physicians who completed DASI training (n = 8) were asked to fill out a questionnaire concerning their opinion of the DASI. Additionally, patients filled out a questionnaire to measure their satisfaction as to the behavioral aspects of the physicians. Results The groups showed no important differences in agreement percentages (mean percentage about 80%) and eligibility for a disability benefit. In 9 out of 21 items the physicians of the control group indicated fewer work limitations compared to physicians using the DASI. All physicians agreed on the fact that the DASI was an acceptable tool in daily practice, one that provided a realistic picture of the patient and provided sufficient information to assess functional limitations. In addition, between the two groups, no differences were found as to the satisfaction of patients concerning the behavioral aspects of the physicians. Conclusion The DASI is a tool with a reasonable to good inter-rater reliability and content validity, and it appears to be acceptable to both patients and physicians. It did not improve inter-observer agreement beyond that of usual interview procedures used in the Netherlands. The DASI would seem to be a worthwhile tool for collecting self-reported information in order to assess functional limitations in claimants.