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Theresa Smith, Lisa Foret, Guy Davis, Kyoko Fujiwara, Robert W Massof; The relationship of Goal Attainment Scaling to an interval measure of low vision rehabilitation functional outcomes. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1975.
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© 2017 Association for Research in Vision and Ophthalmology.
Goal Attainment Scaling (GAS) is an adaptive outcome measure for rehabilitation goals. At evaluation, the therapist identifies the patient’s goals and rates how far the patient is from the expected rehabilitation outcome for each goal (-2, -1, or 0). GAS ratings are repeated at discharge (D/C ) with the addition of two more rating categories (+1 and +2). GAS can be used as a tool for assessing therapists’ biases in selecting goals and judging patients’ rehabilitation potential. In this study, we applied GAS to low vision rehabilitation (LVR) and mapped GAS ratings onto interval-scaled measures of functional ability anchored to patient reports.
The Activity Inventory (AI) was administered to 40 patients. An occupational therapist (OT) specializing in LVR evaluated the patient and developed a plan of care (POC). The OT assigned a Functional Independence Measure (FIM) rating and a FIM rating expected at D/C to each AI goal rated by the patient to be at least somewhat important and at least somewhat difficult. The OT also assigned a GAS rating to each patient’s AI goals based on the patient’s rehabilitation potential and POC. After D/C, the OT assigned FIM and GAS ratings to the same AI goals
Rasch analysis was performed on the FIM ratings of AI goals at baseline and at D/C with item measures anchored to values estimated previously. Average functional reserve (FR) was calculated for each FIM rating category across all person/item combinations to which the rating category was applied. Baseline, targeted and D/C FIM ratings were transformed to FR for patients’ AI goals. Assuming that the targeted FIM represents the expected functional outcome of the POC goal, the difference between FR at baseline and targeted FR was compared to the corresponding baseline GAS rating. The difference between FR at D/C and targeted FR was compared to the corresponding D/C GAS rating. The same monotonic relationship was observed at baseline and D/C between GAS ratings and observed minus targeted FR. FR at D/C equaled or exceeded targeted FR for 84% of the patients.
Interval-scaled measures of FR can be estimated from Rasch analysis of FIM ratings of patients’ goals. If OTs provide estimates of expected FIM ratings of goals after completion of the POC, then the equivalent of GAS ratings can be mapped to the same interval functional ability scale.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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