This study aimed to evaluate the reliability of Section GG, along with Sections B (Hearing, Speech, and Vision) and C (Cognitive Patterns), within the Centers for Medicare and Medicaid Services Inpatient Rehabilitation Facility Patient Assessment Instrument (CMS-IRF PAI) Version 1.4. The research compared these sections to the established Functional Independence Measure (FIM) motor and cognitive subscales.
The study employed a retrospective cohort design at a single inpatient rehabilitation facility. Participants included 1296 patients admitted for stroke rehabilitation between October 2016 and October 2019. No specific interventions were applied for this validation study. The main outcome measures involved comparing scores from Sections GG, B, and C against FIM motor (FIMm) and cognitive (FIMc) subscales using Spearman’s rank correlation coefficient and Bland-Altman analyses to assess agreement and bias.
Results indicated a strong correlation between Section GG and FIMm scores both at admission (ρ=0.919, P<.001) and discharge (ρ=0.929, P<.001). However, Section GG exhibited more pronounced ceiling effects at discharge (8.6%) compared to FIMm. Bland-Altman analysis revealed a bias towards higher scores in Section GG compared to FIMm at both admission (Bias=2.3%, P<.001) and discharge (Bias=6.2%, P<.001). Furthermore, Section GG showed a bias toward greater functional gains (Bias=3.9%, P<.001), particularly in mobility tasks like walking and stair climbing (bias=3.71%, P<.001). Interestingly, self-care items contributed less to the gains observed in Section GG compared to FIMm (bias=-7.5%, P<.001).
The internal consistency of a combined scale using Sections B and C (B+C scale) was found to be good (Cronbach’s alpha=0.868). This B+C scale also showed a strong correlation with FIMc (ρ=0.745). Nevertheless, the B+C scale tended to rate patients at a higher cognitive level (bias=20.0%, P<.001) and presented a greater ceiling effect at admission (20.4%) compared to FIMc (0.6%).
In conclusion, while Sections GG and the B+C scale demonstrate correlation with FIMc and FIMm subscales, they exhibit a tendency to provide higher ability ratings. The presence of ceiling effects, especially at higher levels of cognitive and functional independence, may limit their ability to differentiate among higher-functioning individuals. Further research is necessary to determine the clinical utility of Section GG total scores as a reliable outcome measure and predictor of long-term patient outcomes in rehabilitation settings.
