Using the GAF as a national mental health outcome measure in the Department of Veterans Affairs

Abstract

Objective: Data from the Veterans Health Administration (VHA) were used to evaluate the strengths and weaknesses of the Global Assessment of Functioning (GAF), a single-item mental health status measure, as an outcome measure for large mental health care systems.

Methods: The sample consisted of VHA mental health patients who had at least two GAF scores 45 days apart in 2002 (N=283,754). First, to evaluate the discriminant validity of the GAF change measures, the authors examined the association of these measures with sociodemographic and clinical characteristics. Facility-level risk-adjusted measures of GAF change were then created in three different clinical samples at more than 130 VHA medical centers, adjusting for patients' sociodemographic characteristics and diagnoses. The internal consistency of the scale created by using these items and their consistency across medical centers over time was evaluated.

Results: The analysis supported the discriminant validity of the GAF-derived measures. As expected, veterans who had a diagnosis of schizophrenia or Alzheimer's disease or who had service-connected disability ratings above 50 percent had lower baseline GAF scores and showed less improvement. The overall GAF performance measure had a high level of internal consistency (a standardized alpha of .85) and was highly consistent across facilities over time.

Conclusions: The results of this study provide preliminary empirical support for cautious use of a GAF-derived scale in monitoring changes in average facility-level outcomes over time. However, because of the potential for gaming of the measures and uncontrolled variation in the scale's administration across facilities, the scale should not be used to compare outcomes across facilities.