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

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.