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This work may not be copied, distributed, displayed, Original Research published, reproduced, transmitted, modified, posted, sold, licensed, or used for commercial purposes. By downloading this file, you are agreeing to the Efficacy and Effectiveness of Depot publisher’s Terms & Conditions. Versus Oral Antipsychotics in Schizophrenia: Synthesizing Results Across Different Research Designs Noam Y. Kirson, PhD; Peter J. Weiden, MD; Sander Yermakov, MS; Wayne Huang, MPP; Thomas Samuelson, BA; Steve J. Offord, PhD; Paul E. Greenberg, MS, MA; and Bruce J. O. Wong, MD ABSTRACT he cornerstone of long-term maintenance therapy Objective: Nonadherence is a major challenge in schizophrenia Tof schizophrenia patients is relapse prevention. treatment. While long-acting (depot) antipsychotic medications are Relapse prevention is necessary—albeit not sufficient— often recommended to address adherence problems, evidence on for eventual successful rehabilitation.1 In practice, the the comparative effectiveness of depot versus oral antipsychotics is effectiveness of maintenance antipsychotic treatment is inconsistent. We hypothesize that this inconsistency could be due to often undermined by poor adherence to therapy. Not systematic differences in study design. This review evaluates the effect only is nonadherence the single greatest modifiable of study design on the comparative effectiveness of antipsychotic risk factor for relapse,2,3 it is also often undetected, formulations. The optimal use of different antipsychotic formulations resulting in lost opportunities to employ psychosocial in a general clinical setting depends on better understanding of the underlying reasons for differences in effectiveness across research interventions for adherence, as well as uncertainty as designs. to the relative contribution of lack of efficacy versus Data Sources: A PubMed literature review targeted English-language adherence problems to poor outcomes. studies (2000–2011) with information on relapse, hospitalization, or all- While no single adherence intervention is universally cause discontinuation for depot and oral antipsychotic treatment arms effective, long-acting injectable (depot) formulations are in schizophrenia. The time frame was chosen to reflect research focused considered one of the most important pharmacologic on the newer generation of antipsychotic agents. The search required at interventions available to address adherence problems least 1 term from each of the following categories: (1) schizophrenia; (2) in schizophrenia.4 Relative to oral formulations, long- inject, injection, injectable, injectables, injected, depot, long-acting; and (3) acting depot delivery systems are thought to help iloperidone, fluphenazine, haloperidol, paliperidone, risperidone, olanzapine, maintain adherence (or delay nonadherence) in many asenapine, flupentixol, flupenthixol, lurasidone, clopenthixol, fluspirilene, individuals who would otherwise discontinue their oral zuclopentixol, zuclopenthixol. therapy. Therefore, long-acting depot formulations are Study Selection: Thirteen relevant studies were identified by often recommended for individuals who are known to 2 independent reviewers; these studies included information on have patterns of nonadherence to oral antipsychotic 19 depot-oral comparisons. medication.5,6 Data Extraction: Age- and gender-adjusted risk ratios (RRs) (depot/ However, the findings in the clinical literature oral) were calculated for the identified endpoints and pooled by study regarding the comparative effectiveness of depot design (randomized controlled trial [RCT], prospective observational, and versus oral antipsychotics in schizophrenia have been retrospective observational). Meta-analysis with random effects was used 7–9 to estimate the pooled RRs, by study design. Average conversion factors inconsistent. These findings have challenged the field between study designs were calculated as the ratios of pooled RRs. to consider the proper role of long-acting depot therapy. Some argue that the widely held notion of superiority Results: Meta-analysis of adjusted endpoints showed no apparent 7,10,11 benefit of depot over oral formulations in RCTs, with an RR of 0.89 of long-acting medication is overstated. If so, then (P = .416). In contrast, there was a significant advantage for depot efforts to increase long-acting depot utilization will not formulations in other study designs (prospective RR = 0.62 [P < .001]; yield hoped-for improvements in relapse prevention. retrospective RR = 0.56 [P < .001]). These imply conversion factors of The lack of consistent findings in the literature raises 1.43 and 1.59 between RCTs and prospective and retrospective important practical questions of therapy in managing designs, respectively. schizophrenia. Conclusions: The comparative effectiveness of antipsychotic One hypothesis for the inconsistency in the liter- formulations is sensitive to research design. Depot formulations ature is that the type of study design may influence displayed significant advantages in nonrandomized observational the comparative effectiveness of oral and depot form- studies, whereas in RCTs no difference was observed. The estimated ulations. While identification of outcome differences conversion factors may facilitate comparison across studies. based on study methods will not identify which method J Clin Psychiatry 2013;74(6):568–575 is “correct,” it may provide clues to further research © Copyright 2013 Physicians Postgraduate Press, Inc. on explanatory factors that may account for such differences. From a methodological perspective, RCTs Submitted: September 14, 2012; accepted March 4, 2013. are considered the gold standard in terms of identifying Online ahead of print: April 19, 2013 (doi:10.4088/JCP.12r08167). Corresponding author: Noam Y. Kirson, PhD, Analysis Group, Inc, 111 Huntington Ave, differences in treatment efficacy. RCTs avoid many 10th Fl, Boston, MA 02199 ([email protected]). of the issues associated with confounding and bias 568© 2 01 3 COPYRIGHT PHYSICIANS POSTGRADUATE PRESS, INC. NOT FOR DISTRIBUTION, DISPLAYJ, ClinOR C PsychiatryOMMERCI 74:6,AL P UJuneRPO 2013SES. Effectiveness of Depot vs Oral Antipsychotics that plague observational studies. However, in a disease The comparative effectiveness of depot and oral formulations ■ like schizophrenia, in which adherence is a particularly Clinical Points of antipsychotics in schizophrenia varies by study design. challenging aspect of disease management, a question arises We found that observational designs tend to show favorable as to whether RCTs adequately capture all relevant aspects of outcomes for depot therapy, whereas randomized controlled general clinical practice. For example, researchers in RCTs trials tend to find no differences between oral and depot more carefully monitor patients’ adherence to either oral formulations. or depot treatment, ensuring that randomized treatment regimens are upheld. In addition, adherence to medications ■ In weighing the published clinical evidence, clinicians is a behavior that may be affected by patients’ knowledge should carefully consider the possible effects of study design that they are being observed (ie, the Hawthorne effect).12 on comparative effectiveness of antipsychotic treatment However, in clinical practice, where the default adherence formulations. monitoring may be more lax than in RCTs, there may be differential benefits to depot patients who, by default, studies that reported findings on relapse, hospitalization, or may be more closely monitored than their oral-therapy all-cause discontinuation were included. counterparts. These examples are mentioned not because we have evidence that these relative benefits occur. Rather, Data Extraction and Statistical Analysis we believe that these are reasonable scientific arguments that The selected studies were summarized and data were justify further investigation into the impact of study methods extracted for reported clinical endpoints, treatment in estimating relative effectiveness of depot therapy. dosages, baseline characteristics, inclusion/exclusion Prior studies have not comprehensively examined the criteria, follow-up duration, and frequency of follow-up. effect of study design on the comparative effectiveness When reported, information on event counts and patient of depot and oral formulations of antipsychotics in population in each treatment arm was used to compute risk schizophrenia. Building on a cross-design synthesis ratios (RRs) (depot/oral; RR < 1 favors depot, representing methodology13 and using meta-analysis techniques,14 this a lower relative risk for depot formulations compared with article aims to quantify the effect of study design on the oral formulations) for all relevant endpoints (ie, relapse, comparative effectiveness of oral and depot formulations hospitalization, all-cause discontinuation). In a limited of antipsychotics in schizophrenia to facilitate comparisons number of cases, the number of patients with a given event across studies. was derived from reported hazard rates and sample sizes. METHOD Adjusting for Baseline Differences in Gender and Age Data Source and Study Selection Using reported gender and age at baseline, we reweighted A targeted literature review was conducted using PubMed. endpoints to account for demographic differences across The PubMed database was queried for publications between treatment arms. Gender was adjusted on the basis of the January 1, 2000, and December 31, 2011. The time frame