Goal attainment scaling as an outcome measure for randomised controlled trials: a scoping review

Objectives: (1) Identify the healthcare settings in which goal attainment scaling (GAS) has been used as an outcome measure in randomised controlled trials. (2) Describe how GAS has been implemented by researchers in those trials.

Design: Scoping review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews approach.

Data sources: PubMed, CENTRAL, EMBASE and PsycINFO were searched through 28 February 2022.

Eligibility criteria: English-language publications reporting on research where adults in healthcare settings were recruited to a randomised controlled trial where GAS was an outcome measure.

Data extraction and synthesis: Two independent reviewers completed data extraction. Data collected underwent descriptive statistics.

Results: Of 1,838 articles screened, 38 studies were included. These studies were most frequently conducted in rehabilitation (58%) and geriatric medicine (24%) disciplines/populations. Sample sizes ranged from 8 to 468, with a median of 51 participants (IQR: 30-96). A number of studies did not report on implementation aspects such as the personnel involved (26%), the training provided (79%) and the calibration and review mechanisms (87%). Not all trials used the same scale, with 24% varying from the traditional five-point scale. Outcome attainment was scored in various manners (self-report: 21%; observed: 26%; both self-report and observed: 8%; and not reported: 45%), and the calculation of GAS scores differed between trials (raw score: 21%; T score: 47%; other: 21%; and not reported: 66%).

Conclusions: GAS has been used as an outcome measure across a wide range of disciplines and trial settings. However, there are inadequacies and inconsistencies in how it has been applied and implemented. Developing a cross-disciplinary practical guide to support a degree of standardisation in its implementation may be beneficial in increasing the reliability and comparability of trial results.

Prospero registration number: CRD42021237541.