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Clozapine Treatment and Offending: A Within-Subject Study of Patients With Psychotic Disorders in Sweden

Research output: Contribution to journalArticle

Vishal Bhavsar, Kyriaki Kosidou, Linnea Widman, Nicola Orsini, John Hodsoll, Christina Dalman, James H. MacCabe

Original languageEnglish
Pages (from-to)303-310
Number of pages8
JournalSchizophrenia Bulletin
Issue number2
Early online date31 May 2019
Publication statusPublished - Mar 2020

King's Authors


Clozapine treatment may have beneficial effects on behavioral outcomes in psychotic disorders, including violent offending. Although clozapine and other antipsychotics have been linked to lower levels of violent behavior, these have been primarily in small selected samples, and population-based estimates have been limited and imprecise. We aimed to assess the effect of clozapine treatment on the rate of violent and nonviolent offending. We carried out a within-person mirror-image study of the Swedish population with linked prescription, hospitalization, and sociodemographic registers. Outcomes were violent, nonviolent, and overall offences occurring before and after clozapine, or olanzapine, initiation. Comparison of effects of clozapine and olanzapine on key variables was modeled with interaction terms. We found periods of mirror-image observation time with clozapine treatment were associated with a much lower rate of violent offending compared to periods before treatment (rate ratio [RR]: 0.13 (95% CI: 0.05, 0.34). Reductions in nonviolent offences were smaller in magnitude (RR: 0.37, 95% CI: 0.17, 0.80). There was a statistically greater rate reduction effect on violent offences for clozapine than olanzapine (RR for interaction: 4.84, 95% CI: 1.56, 14.86, P = .002). In patients with psychotic disorders, clozapine treatment is associated with a lower rate of violent offending compared to olanzapine.

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