Side effects of clozapine in older adults with treatment‐resistant schizophrenia compared to younger adults

• Published in: International journal of geriatric psychiatry Vol. 39; no. 1; pp. e6051 - n/a
• Main Authors: Groenewald, Floor C. E., Kok, Rob M.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.01.2024
• Subjects: Age groups; Aged; Clozapine; Clozapine - adverse effects; Constipation; Extrapyramidal system; Geriatric psychiatry; Humans; Mental disorders; Mental Health; older adults; Older people; Retrospective Studies; Schizophrenia; Schizophrenia - drug therapy; Schizophrenia, Treatment-Resistant; Side effects; Tachycardia; treatment‐resistant schizophrenia; older adults; clozapine; side effects; treatment-resistant schizophrenia
• ISSN: 0885-6230; 1099-1166
• DOI: 10.1002/gps.6051

Objectives To study the differences in side effects of clozapine between older adults aged ≥55 years and younger adults aged 18–55 years with treatment‐resistant schizophrenia. Methods A retrospective cohort study in a large mental health institute in the Netherlands. All patients diagnosed with treatment‐resistant schizophrenia who started with clozapine between 2011 and 2020 (N = 284) were included. We compared the number and type of side effects reported in the electronic patient files as well as the number of treatment discontinuations and the time until discontinuation, both due to side effects, of older adults versus younger adults. Results In the younger age group (N = 183), the number of reported side effects was significantly higher in the first 3 months of treatment (Mann–Whitney U = 7341.5, p = 0.004) and after those 3 months (Mann–Whitney U = 5668.5, p < 0.001) compared with the number reported in the older age group (N = 101). Sedation, hypersalivation, dizziness, tachycardia, heartburn, nausea, weight gain, and constipation were reported significantly more often in the younger age group, and only extrapyramidal symptoms were reported significantly more often in the older age group. There was no significant difference in the number of treatment discontinuations due to side effects (23% vs. 21.8%, Chi‐2 = 0.051, df = 1, p = 0.821) and time until discontinuation due to side effects (b = 0.091, SE = 0.335, p = 0.798) between younger and older adults. Conclusions Side effects of clozapine were reported significantly less often in older patients compared with younger patients. Older patients did not discontinue treatment due to side effects more often or earlier than younger patients. Older patients with schizophrenia may not be more vulnerable to side effects than younger adults. Key points Only a few studies are published on the use of clozapine in older patients with treatment‐resistant schizophrenia. Contrary to our expectations, side effects of clozapine were reported significantly less often in older patients compared with younger patients and discontinuation rates did not differ significantly. This study suggest that older patients with treatment‐resistant schizophrenia may not be more vulnerable, and perhaps are even less vulnerable, to side effects than younger adults.