Glasgow Antipsychotic Side-effects Scale for Clozapine - Development and validation of a clozapine-specific side-effects scale.
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.


CONCLUSIONS
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.
Saint John of God Hospital, Stillorgan, Co. Dublin, Ireland. Electronic address: carolinehynes@gmail.com.
Caroline
C
Hynes
Saint John of God Hospital, Stillorgan, Co. Dublin, Ireland. Electronic address: dolores.keating@sjog.ie.
Dolores
D
Keating
Saint John of God Hospital, Stillorgan, Co. Dublin, Ireland. Electronic address: stephen.mcwilliams@sjog.ie.
Stephen
S
McWilliams
DETECT Early Intervention in Psychosis Service, Dublin, Ireland. Electronic address: kevin.madigan@sjog.ie.
Kevin
K
Madigan
DETECT Early Intervention in Psychosis Service, Dublin, Ireland. Electronic address: akinsella212@gmail.com.
Anthony
A
Kinsella
Aston University, School of Life and Health Sciences, Birmingham, United Kingdom. Electronic address: i.maidment@aston.ac.uk.
Ian
I
Maidment
Aston University, School of Life and Health Sciences, Birmingham, United Kingdom. Electronic address: celiafeetam@madasafish.com.
Celia
C
Feetam
University of Manchester, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. Electronic address: richard.drake@manchester.ac.uk.
Richard J
RJ
Drake
Greater Manchester Health NHS Foundation Trust, Manchester, United Kingdom. Electronic address: peterhaddad@doctors.org.uk.
Peter M
PM
Haddad
South London and Maudsley NHS Foundation Trust, National Psychosis Unit, London, United Kingdom. Electronic address: fiona.1.gaughran@kcl.ac.uk.
Fiona
F
Gaughran
NHS Lothian, Edinburgh, United Kingdom. Electronic address: marktaylor2@nhs.net.
Mark
M
Taylor
DETECT Early Intervention in Psychosis Service, Dublin, Ireland. Electronic address: mary.clarke@sjog.ie.
Mary
M
Clarke
D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects*; D003024:Clozapine / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007494:Ireland; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D006113:United Kingdom; D055815:Young Adult
D014150:Antipsychotic Agents; D003024:Clozapine
Adverse effects; Atypical antipsychotic agent; Checklist; Drug monitoring; Questionnaire