Responsiveness of the activity measure for post-acute care (AM-PAC) from discharge from inpatient stroke rehabilitation to six month follow-up

Abstract

Functional stroke scales must detect significant change over time, but defining “significant” is difficult. The activity measure for post-acute care (AM-PAC) measures activity limitations in 3 domains: basic mobility (BM), daily activity (DA), and applied cognitive (AC). This study assesses the ability of the AM-PAC to detect change from inpatient rehabilitation facility (IRF) discharge (DC) to an outpatient setting 6 months (6 M) later. We analyzed data from a observational database for stroke patients treated at our academic IRF. We assessed AM-PAC domains at IRF DC and again by phone 6 M later. Change between DC and 6 M was calculated by: – standardized response mean (SRM, 0–0.4–0.6 = moderate effect); – proportion achieving the minimal clinically important difference (MCID, estimated as 0.5SD of baseline scores after Norman et al., 2003) with our data; – the published, mixed population minimal detectable change (MDC). Of 273 patients at DC, 139 (51%) had both AM-PAC scores and were included. Those included were not demographically different but were better on physical and cognitive measures at IRF admission. The mean age = 67.1 ± 14.8 y, NIHSS = 7.9 ± 7.5, discharge FIM = 84.1 ± 19.1, FIM Gain = 20.2 ± 10.6, and rehabilitation length of stay = 14.8 ± 7.6d. The mean DC/6 M scores for BM were 51.7 ± 11.2/56.0 + 12.1, DA = 44.4 ± 9.9/49.2 + 14.5 and AC = 40.0 ± 9.8/44.7 + 9.2. Change metrics for the 3 AM-PAC domains are given in Table 1 . Between 40%–50% of stroke patients were classified as “significantly” improved, depending on measure, suggesting the AM-PAC is able to capture “real life” change. The sample experienced change at the lower end of “moderate improvement” by SRM. Estimated MCID and the MDC were similar for DA and AC, not BM. Further research should explore factors, which predict functional success or failure.