Glasgow antipsychotic side-effects scale for Clozapine - development and validation of a clozapine-specific side-effects scale

Caroline Hynes*, Dolores Keating, Stephen McWilliams, Kevin Madigan, Anthony Kinsella, Ian Maidment, Celia Feetam, Richard J. Drake, Peter M. Haddad, Fiona Gaughran, Mark Taylor, Mary Clarke

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

OBJECTIVE: The authors developed and validated a clozapine-specific side-effects scale capable of eliciting the subjectively unpleasant side-effects of clozapine.

METHODS: Questions from the original Glasgow Antipsychotic Side-effects Scale (GASS) were compared to a list of the most commonly reported clozapine side-effects and those with a significant subjective burden were included in the GASS for Clozapine (GASS-C). The original authors of the GASS and a group of mental health professionals from the UK and Ireland were enlisted to comment on the questions in the GASS-C based on their clinical experience. 110 clozapine outpatients from two sites completed the GASS-C, the original GASS and a repeat GASS-C. Statistical analyses were performed using SPSS for Windows version 19.

RESULTS: The GASS-C was shown to have construct validity, in that Spearman's correlation coefficient was 0.816 (p<0.001) with the original GASS, whilst Cohen's kappa coefficient was >0.77 (p<0.001) for one question and >0.81 (p<0.001) for remaining relevant questions. GASS-C was also shown to have strong test-retest reliability, in that Cronbach's alpha coefficient was >0.907 (p<0.001), whilst Cohen's kappa coefficient was >0.81 (p<0.001) for 12 questions and >0.61 (p<0.001) for the remaining four questions.

CONCLUSION: The GASS-C is a valid and reliable clinical tool to enable a systematic assessment of the subjectively unpleasant side-effects of clozapine. Future research should focus on how the scale can be utilised as a clinical tool to improve real-world outcomes such as adherence to clozapine therapy and quality of life.

Original languageEnglish
Article number6507
Pages (from-to)505-513
Number of pages9
JournalSchizophrenia Research
Volume168
Issue number1-2
Early online date12 Aug 2015
DOIs
Publication statusPublished - Oct 2015

Bibliographical note

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Keywords

  • adverse effects
  • atypical antipsychotic agent
  • checklist
  • drug monitoring
  • questionnaire

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