روابط بین ارزیابی کلی کارکرد و سایر مقیاس های رتبه بندی در مطالعات بالینی برای اسکیزوفرنی

The relationship between the Global Assessment of Functioning (GAF) with other scales in schizophrenia has rarely been investigated. A systematic literature search was conducted to identify articles that reported the GAF score together with scores in the Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression (CGI) or Brief Psychiatric Rating Scale (BPRS), using MEDLINE, EMBASE and PsycINFO, with keywords of schizophrenia, clinical trial and global assessment of functioning (last search 30 June 2013). Correlational analyses with weighting by the study participant numbers across these rating scales were performed. In 40 clinical trials (n=8000) that reported cross-sectional data on the GAF and PANSS, a significant but modest correlation was noted (Pearson׳s r=−0.401, p<0.0001). Furthermore, a correlation between the GAF and CGI-severity (CGI-S) at study baseline in 38 studies (n=11,315) was robust (r=−0.893, p<0.0001). In longitudinal studies, changes in the GAF scores were negatively correlated with those in the PANSS as well as CGI-S scores (p<0.0001 for both). Data on the BPRS were all statistically significant although relatively scarce. While optimal degree of concordance is undetermined among psychiatric scales that are presumed to be measuring different but overlapping constructs, this study found significant correlations in the GAF and CGI-S or PANSS, both cross-sectionally and longitudinally. The GAF-CGI-S relationship was especially tighter, making it a reliable clinical indicator.

Recently the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) eliminated the Global Assessment of Functioning (GAF) (American Psychiatric Association, 1994) because a single score from the GAF is unlikely to convey information to adequately assess diagnosis, severity of symptoms and diagnosis, dangerousness to self or others, and disability in social and self-care spheres, which are likely to vary independently over time, and because the GAF requires specific training to be used properly. Nevertheless, global functioning in schizophrenia represents an important outcome and a heuristic endpoint in the real-world clinical practice since functional impairment is an obvious obstacle against social integration. Measuring this outcome is important from the viewpoint of any successful treatment aiming for remission and recovery (Lieberman et al., 2008). For that purpose, the GAF amongst others has been occasionally utilized (Suzuki, 2011). However, to the best of authors׳ knowledge, global functioning in schizophrenia has rarely been the primary outcome measure in clinical trials and its relationship with other commonly utilized rating scales has rarely been a topic of investigation. “Measuring” outcome, frequently commenced with the existing rating scales, is of utmost importance to critically appraise the effect of any interventions including psychopharmacotherapy for schizophrenia. To address the gap in the literature, we examined the correlations between the GAF and other frequently recorded scales i.e., the Positive and Negative Syndrome Scale (PANSS) (Kay et al., 1987), the Clinical Global Impression (CGI) (Guy, 1976) and the Brief Psychiatric Rating Scale (BPRS) (Overall and Gorham, 1988) in clinical trials for schizophrenia, in order to shed light on their cross-sectional and longitudinal correlations and their robustness.

An effort to quantify real-world outcome is surely a complex task in schizophrenia (Leifker et al., 2011) and global functioning may represent a tip of the iceberg, which emphasizes the need of further investigations. In conclusion, in clinical trials for schizophrenia, the correlations between the GAF and the PANSS or CGI-S were significant, and the link between the GAF and CGI-S, both cross-sectionally and longitudinally, was especially tight, which makes it a reliable indicator. The data presented herein would hopefully serve as an anchor relationship between the scales, in an effort to improve clinical management and set realistic goals for patients with schizophrenia.