Evaluation of adherence in patients prescribed long-acting injectable antipsychotics: A comparison of biweekly versus monthly administered neuroleptics.

Background: Long-acting injectable antipsychotics (LAIAs) have been developed to decrease medication nonadherence. LAIAs are usually given biweekly or monthly, with the exception of new 3-month and 6-week formulations. There has been no known evaluation regarding whether the frequency of LAIA formulation affects adherence. The purpose of this study is to evaluate whether there is a difference in adherence between LAIAs administered biweekly or monthly.

Methods: Eligible participants were identified from the Louis Stokes Cleveland VA electronic medical record as having an active prescription for a LAIA between September 1, 2009, and September 1, 2014. Participants were then evaluated using inclusion and exclusion criteria to determine study entrance. Medication possession ratios (MPRs) were calculated for each participant to determine adherence for comparison of objectives. Descriptive statistics and tests were used to identify significant differences between groups.

Results: There were 128 participants enrolled based on eligibility criteria. There were no differences in MPRs for biweekly versus monthly administered LAIAs (0.98 versus 0.97, respectively;  = .691). No differences in adherence were observed between first- and second-generation LAIAs (0.98 versus 0.98, respectively;  = .975), or for risperidone LAI versus paliperidone palmitate (0.97 versus 0.99, respectively;  = .269). Hospitalizations were observed to decrease by 61% after LAIA initiation ( = .021).

Discussion: Based on the findings of this retrospective cohort review, there was no difference in adherence in patients prescribed biweekly versus monthly injected LAIAs. Patient preference and response, safety, tolerability, cost, and availability of follow-up appointments should be other factors to take into consideration for agent selection.