GAS - Goal Attainment Scaling in Rehabilitation

GAS is a method of scoring the extent to which patient’s individual goals are achieved in the course of intervention. In effect, each patient has their own outcome measure but this is scored in a standardised way as to allow statistical analysis. Traditional standardised measures include a standard set of tasks (items) each rated on a standard level. In GAS, tasks are individually identified to suit the patient, and the levels are individually set around their current and expected levels of performance.

How is GAS rated?

An important feature of GAS is the ‘a priori ‘ establishment of criteria for a ‘successful’ outcome in that individual, which is agreed with the patient and family before intervention starts so that everyone has a realistic expectation of what is likely to be achieved, and agrees that this would be worth striving for. Each goal is rated on a 5-point scale, with the degree of attainment captured for each goal area:

If the patient achieves the expected level, this is scored at 0.

If they achieve a better than expected outcome this is scored at:

+1 (more than expected)

+2 (much more than expected)

 

If they achieve a worse than expected outcome this is scored at:

-1 (less than expected) or

-2 (much less than expected)

Goals may be weighted to take account of the relative importance of the goal to the individual, and/or the anticipated difficulty of achieving it.

GAS depends on two things – the patient’s ability to achieve their goals and the clinician’s ability to predict outcome, which requires knowledge and experience. A computerised programme calculates the baseline score, the T Score (achieved score) and change score. This is available as a stand alone Excel file or within the UKROC software. 

Our department has led an international programme of work to encourage the consistent use of GAS in routine clinical practice. This has led to the development of the following resources:

  • the GAS-Light – a simplified version of GAS designed to be usable in routine clinical practice
  • a verbal rating scale for clinicians who prefer verbal descriptors to numbers
  • a GAS calculation spreadsheet for calculating GAS T scores
  • Scales to measure patient engagement in goal setting and their satisfaction with the goals selected

These resources are free to use and may be downloaded by clicking the links below

GAS Calculation Sheet

GAS Practical Guide

GAS-Light only

GAS Verbal Record Sheet

GAS Engagement Scales

 

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