Comparison of standard goal attainment scaling (GAS) and the GAS-light method for evaluation of goal attainment during neurorehabilitation of the upper limb

Background: Goal attainment scaling (GAS) is now widely used as a person-centered measure of outcome from rehabilitation and has demonstrated validity in diverse populations with sensitivity to change. However, as originally described, it is time-consuming for use in busy clinical settings. The "GAS-light" is a simplified version designed for application in routine clinical practice. Although increasingly taken up by clinicians, published evidence of the validity of GAS-light method is currently lacking. Objective: To evaluate the validity and sensitivity of the GAS-light rating method as a measure of goal attainment in clinical neurorehabilitation practice. To examine its agreement with the standard GAS rating (as originally described by the developers) as the gold standard and to assess its clinical utility and acceptability. Methods design: A direct, head-to-head comparison of the 2 GAS rating methods in a cohort of adults undergoing upper limb motor rehabilitation programs across a range of rehabilitation settings, including hospital, community outpatient, and spasticity clinic services. Study population: 60 patients (n=54 poststroke) set a total of 136 goals (range 1-4 per patient). In this comparative study, patients acted as their own controls. Measures: The 2 rating methods were applied independently and in parallel from a single goal-setting discussion. Goal attainment was measured on the original 5-point GAS using a predetermined follow-up guide and the GAS-light with its 6-point verbal rating scale. The evaluation included concurrent validity (intraclass correlation coefficients and agreement between the 2 ratings) and sensitivity to change using the standardized response mean (SRM). Thirteen clinicians and 52 participants completed surveys of clinical utility and patient acceptance, respectively. Results: Individual absolute agreement of 2-way mixed-effects intraclass correlation between the tools indicated good agreement (ICC(A,1)=0.88, 95% CI: 0.80, 0.93), and small systematic bias (-1.72 (95% CI: -3.04, -0.41). Both tools measured similar levels of change over time (GAS SRM=1.79; GAS-light SRM=1.62). Clinicians perceived GAS-light had stronger clinical utility, being quicker and easier to administer, score, and understand. Patients perceived GAS-light as acceptable, comfortable, worthwhile, and helpful. Conclusions: GAS-light is reliable and sensitive to change, with better clinical utility than the standard GAS. Either tool may be used to assess goal attainment in clinical upper limb neurorehabilitation.