Global Assessment of Functioning

The Global Assessment of Functioning (GAF) is a numeric scale used by mental health clinicians and physicians to rate subjectively the social, occupational, and psychological functioning of an individual, e.g., how well one is meeting various problems-in-living. Scores range from 100 (extremely high functioning) to 1 (severely impaired).

The scale was included in DSM-IV, but replaced in DSM-5 with the WHODAS (WHO Disability Assessment Schedule), a survey or interview with detailed items The WHODAS is supposed to be more detailed and objective than a single global impression. The main advantage of the GAF would be its brevity.

Interest in a quantifiable global rating of functioning date back to as early as 1962 with the publication of the Health-Sickness Rating Scale (which was rated 0 to 100) by Luborsky et al. in the paper "Clinicians' Judgements of Mental Health". This was subsequently revised in 1976 as the Global Assessment Scale (GAS) in the paper "The Global Assessment Scale:Procedure for Measuring Overall Severity of Psychiatric Disturbance" by Endicott et al. The rating scale was further modified and published as the Global Assessment of Functioning Scale in the DSM-III-R and DSM-IV. Some versions of the scale stopped at 90 as the maximum score, and others extended to 100. Because the scale was most often used with people seeking health services, it would be rare to have scores over 90, as they would indicate not just a lack of symptoms, but also "superior functioning."

The related SOFAS (Social and Occupational Functioning Assessment Scale) scale was initially described in a paper by Goldman et al. in 1992 in the paper "Revising Axis V for DSM-IV: A review of measures of social functioning." The DSM-IV included the SOFAS within the section "Criteria Sets and Axes Provided for Further Study." The SOFAS scale is similar to the GAF, but it only looks at social and occupational functioning rather than also considering symptom severity.

DSM-5 removed the multiaxial system, including Axis V disability and functioning; and the DSM-5 Task Force recommended the GAF be replaced by the WHO Disability Assessment Schedule (WHODAS 2.0) in an effort to increase the reliability of scores.

Montalvo attempts to substitute "overall level of functioning and carrying out activities of daily living" with "social, occupational, or school functioning". It is possible to see the recourse of some degree of overlap because "social functioning" is arguably a subset of overall functioning and activities of daily living. However, it is arguable whether equivalence is clearly stated in DSM-IV-TR.

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