The Glasgow antipsychotic side-effects scale for clozapine in inpatients and outpatients with schizophrenia or schizoaffective disorder

Abstract

Background: The inconsistency in clinician and patient ratings of clozapine-induced side effects underscore the need to supplement clinician-based estimates of side effects with patient-reported ones.

Aims: The main aims of the study are validation of the Glasgow antipsychotic side-effects scale for clozapine (GASS-C) in Serbian inpatients/outpatients with schizophrenia or schizo-affective disorder and recommendations for its future use, based on common and rare clozapine-associated side-effects.

Methods: The GASS-C was administered to 95 outpatients/inpatients diagnosed with schizophrenia, schizoaffective, or chronic psychotic disorder.

Results: The scale showed good overall reliability, with an internal consistency coefficient of α = 0.84, an average retest coefficient of rho = 0.76, and a Spearman–Brown coefficient of validity of 0.81. Side effects were absent or mild in 64.2% of the patients, moderate in 31.6%, severe in 4.2%; 14% of the subjects considered their symptoms distressing. The most commonly reported side-effects were drowsiness, thirst, frequent urination, and dry mouth. Women reported more side effects than men, and patients not in a relationship reported significantly fewer side effects than patients in a relationship. Results indicate a weak positive correlation (rho = 0.231; p = .025) between severity of side effects and clozapine dose.

Conclusions: The GASS-C showed good psychometric characteristics in clinical population of patients on clozapine. In future studies, clozapine serum concentrations should be measured when using the GASS-C to monitor side effects.

Keywords:

• GASS-C
• clozapine
• side effects

Acknowledgments

The knowledge acquired in the project Research Ethics Education in the Balkans and Black Sea Countries, Fogarty International Program helped in preparation of this article.

Disclosure statement

The authors report no conflicts of interest.

Additional information

Funding

Hereby authors would like to express gratitude to the Grant No175014 and 175007 of Ministry of Science and Technological Development of The Republic Serbia, out of which this study was partially financed.