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AIDS Research and Treatment
Volume 2014 (2014), Article ID 967073, 6 pages
Review Article

The Effect on Treatment Adherence of Administering Drugs as Fixed-Dose Combinations versus as Separate Pills: Systematic Review and Meta-Analysis

1Division of Infectious Diseases, Tropical Medicine and AIDS, Academic Medical Center, Amsterdam, The Netherlands
2Department of Medical Psychology (J3-219-1), Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands

Received 15 May 2014; Accepted 19 August 2014; Published 4 September 2014

Academic Editor: David Katzenstein

Copyright © 2014 Katy A. van Galen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Administering drugs as fixed-dose combinations (FDCs) versus the same active drugs administered as separate pills is assumed to enhance treatment adherence. We synthesized evidence from randomized controlled trials (RCTs) about the effect of FDCs versus separate pills on adherence. We searched PubMed for RCTs comparing a FDC with the same active drugs administered as separate pills, including a quantitative estimate of treatment adherence, without restriction to medical condition. The odds ratio (OR) of optimal adherence with FDCs versus separate pills was used as common effect size and aggregated into a pooled effect estimate using a random effect model with inverse variance weights. Out of 1258 articles screened, only six studies fulfilled inclusion criteria. Across medical conditions, administering drugs as FDC significantly increased the likelihood of optimal adherence (OR 1.33 (95% CI, 1.03–1.71)). Within subgroups of specific medical conditions, the favourable effect of FDCs on adherence was of borderline statistical significance for HIV infection only (OR 1.46 (95% CI, 1.00–2.13)). We observed a remarkable paucity of RCTs comparing the effect on adherence of administering drugs as FDC versus as separate pills. Administering drugs as FDC improved medication adherence. However, this conclusion is based on a limited number of RCTs only.