The assessment of symptom severity and functional impairment with DSM-IV axis V

The Global Assessment of Functioning scale (GAF) is included as axis V in the DSM-IV multiaxial diagnostic system. The GAF is simple to administer and routinely used in treatment planning and as a measure of program performance. The GAF assesses both symptom severity and functional impairment, but the resultant rating provides no information about the contribution of each of these domains. This study aimed to improve the clinical utility of the GAF by creating subscales.

The authors divided the scale into its two principal domains: descriptors of social and occupational functioning (SOFAS) and descriptors of symptoms (GAF minus SOFAS descriptors). These and other measures of symptoms and functioning were used to assess 407 patients while acutely psychotic and again after treatment.

Symptom scores were of greater severity than functional impairment scores in most cases. Because of this, the GAF score tended to reflect symptom severity rather than functional impairment. The symptom rating was more strongly correlated with measures of positive symptoms, and the functional rating had higher associations with negative symptoms and functional impairment. Both scales were good indicators of clinical change.

Findings indicate that GAF ratings for patients with psychosis tend to reflect symptom severity rather than functional impairment. Splitting the GAF into two parts resulted in greater discrimination for this patient group yet retained ease of administration.