Abstract
Purpose :
To compare occupational therapist (OT) Functional Independence Measure (FIM) ratings of functional abilities to low vision patient self-reports using the Activity Inventory (AI).
Methods :
136 low vision rehabilitation patients served by 10 different OTs rated the importance and difficulty of goals in the AI before and after rehabilitation. For each goal rated with nonzero importance and difficulty, the patient’s OT also rated the patient’s independence using the FIM.
Ratings were analyzed using a Rasch model: The Method of Successive Dichotomizations (MSD), in R with item measures anchored. This allowed us to compare person measures estimated from patient ratings and from therapist ratings on the same scale.
Results :
Rater bias can be estimated from the intercepts of Deming regression lines fitted to the pre- and post-rehabilitation data. The intercept for pre-rehabilitation data was -1.48 logits (SE = 0.24), while for post-rehabilitation it was 0.09 logits (SE = 0.24). This shows that patients and OTs were in agreement post-rehabilitation, but that OTs underestimated patients’ functional abilities at baseline. In both cases the slopes were not significantly different from 1. The average difference between person measures from pre to post was 1.60 logits for OTs and 0.28 logits for patients rating themselves.
Conclusions :
Our findings indicate a strong bias leading to overestimation of improvement in functional ability measures based on OT ratings relative to outcome measures based on patient self-reports in low vision rehabilitation.
This is a 2021 ARVO Annual Meeting abstract.