Introduction: Non-adherence to antipsychotics, which plays a critical role in the treatment of individuals with severe mental disorders, is the most significant predictor of relapse. The effectiveness of long-acting injectable antipsychotics (LAIs) in ensuring treatment adherence and preventing relapse is well established. However, studies examining the factors influencing the clinical choice between first-generation and second-generation LAIs and the adherence differences between them are limited. This study aimed to compare patients with schizophrenia and bipolar disorder, who were hospitalized and discharged on either a first- or second-generation LAI, in terms of LAI choice, factors influencing adherence to LAIs, and adherence differences between the two groups of LAIs.
Methods: Our study is a naturalistic, follow-up study. The sample consists of 187 patients (99 females, 88 males) who were hospitalized, initiated on LAI treatment, and discharged. Sociodemographic and clinical information was obtained from patient records. Patients and/or their relatives were contacted by phone at 3, 6, and 12 months after discharge to assess treatment continuation, and this information was verified through health system records.
Results: First-generation LAIs were more frequently chosen for patients who were unemployed, diagnosed with schizophrenia, had a longer illness duration, had a higher number of prior hospitalizations, exhibited homicidal behavior, or had a history of electroconvulsive therapy (p<0.05). Patients with alcohol or substance-use developed non-adherence to treatment earlier (p<0.05). Treatment adherence was higher in patients with bipolar disorder (p=0.025). Adherence to second-generation LAIs at 12 months was higher compared to first-generation LAIs. Adherence was particularly higher with long-acting (LA) aripiprazole and LA paliperidone compared to the other three LAIs (haloperidol, risperidone, and zuclopenthixol) (p<0.05). Adherence to treatment prior to hospitalization significantly predicted LAI adherence at 12 months (p<0.001). Adherence to LAIs administered every four weeks was higher than those administered every two weeks (p=0.014).
Conclusion: For patients expected to face challenges with adherence to LAIs, second-generation agents with longer administration intervals may be preferred.
Keywords: Aripiprazole, bipolar disorder, depot antipsychotic, long-acting