Individual-level responsiveness of the original and short-form postural assessment scale for stroke patients

Background. The group-level responsiveness of the Postural Assessment Scale for Stroke Patients (PASS) is similar to that of the short-form PASS (SFPASS). This result is counterintuitive because the PASS has more items (12) and response levels (4) than does the SFPASS (5 items and 3 response levels). Objective. The purpose of this study was to compare individual-level responsiveness between both measures to determine whether the SFPASS can detect change with as much sensitivity as the PASS. Study Design and Setting. Two hundred fifty-one patients were assessed using the PASS at 14 and 30 days after stroke onset in a medical center. Methods. The SFPASS scores were calculated from the patients' responses on the PASS. Individual-level responsiveness was calculated on the basis of the value of minimal detectable change (MDC). If a patient's change score was greater than the MDC of the PASS or SFPASS, his or her improvement was considered significant. The difference in the number of patients scoring greater than the MDC and the units of MDC (the MDC ratio) improved by the patients on both measures was examined. Results. Fifty-three percent of the patients scored greater than the MDC of the PASS, whereas 43.0% of the patients scored greater than the MDC of the SFPASS. The difference was significant. The mean (±SD) MDC ratio of the PASS (1.8±1.7) was significantly higher than that of the SFPASS (1.2 ±1.3). Limitations. The scores of the SFPASS were retrieved from those of the PASS, which limits the generalization of our findings. Conclusions. The PASS has better individual-level responsiveness than does the SFPASS. To comprehensively report effects of clinical trials, future studies using the PASS should report the individual-level effect (eg, number of patients scoring greater than the MDC).