Examining the Function In Sitting Test for Validity,Responsiveness, and Minimal Clinically Important Difference in Inpatient Rehabilitation

ObjectivesTo determine the responsiveness of the Function In Sitting Test (FIST), compare scores at admission and discharge from inpatient rehabilitation (IPR) with other balance and function measures, and determine the minimal clinically important difference (MCID).DesignProspective, nonblinded, reference-standard comparison study.SettingFour accredited inpatient rehabilitation units.ParticipantsPopulation-based sample of adults (N=125) with sitting balance dysfunction, excluding persons with spinal cord injury, significant bracing/orthotics, and inability to perform testing safely.InterventionsNot applicable.Main Outcome MeasuresFIST, FIM, and Berg Balance Scale (BBS) at admission and discharge, and Global Rating of Change for function and balance at discharge.ResultsThe FIST demonstrated good to excellent concurrent validity with the BBS and FIM at admission and discharge (Spearman ρ=.71–.85). Significant improvement (P<.000; 95% confidence interval [CI], 10.73–15.41) occurred in the FIST from admission (mean ± SD: 36.81±15.53) to discharge (mean ± SD: 49.88±6.90). The standard error of measurement for the FIST was 1.40, resulting in a minimal detectable change of 5.5 points. The receiver operator characteristic curve differentiated participants with meaningful balance changes (area under the curve, .78; P>.000; 95% CI, .66–.91), with a change in FIST score of ≥6.5 points designating the MCID. Findings support the strong responsiveness of the FIST during IPR as evidenced by the large effect size (.83), standardized response mean (1.04), and index of responsiveness (1.07).ConclusionsIn this study, the FIST correlated well with balance and function measures (concurrent validity) and was responsive to change during IPR. A clinically meaningful change was indicated by an increase in score of ≥6.5 points.