Factors that affect continuation of antipsychotic long-acting injections

Long-acting injection (LAI) is a drug administration method that reduces symptoms and prevents recurrence or relapse of schizophrenia. We examined factors related to the continuation of LAI treatment. The study population included patients with schizophrenia who were undergoing LAI treatment involving risperidone, paliperidone, or aripiprazole at Fujita Health University Hospital between October 2009 and June 2017. We assessed the continuation rate of LAI treatment at six months, and collected patient characteristics such as medication history. Furthermore, we classified patients into two clusters according to the reason for introducing LAI based on a previous study (Prog. Neuropsychopharmacol. Biol. Psychiatry, 2008, Heres et al.). The study included 82 patients (mean age, 44.9±15.0 years); the continuation rate of LAI after six months was 63.4%. Factors that affected LAI continuation included cluster II [adjusted odds ratio (OR): 5.74, p=0.017], switching from the same component as LAI (adjusted OR: 7.13, p<0.001), and diazepam conversion rate (adjusted OR: 0.88, p<0.001). LAI significantly improved the continuation rate of treatment in the patient group belonging to cluster II. Furthermore, based on other factors and reasons for discontinuation, LAI should be preferably commenced in patients with a more stable condition.