Polypharmacy in multimorbid older adults: protocol for a systematic review

Background: Polypharmacy, the concurrent use of multiple medications, consistently evokes a negative connotation, notably because it is associated with a plethora of adverse events. Nonetheless, the number of individuals exposed to polypharmacy is increasing steeply, especially for older people with multiple diseases. There is a need to carefully study the phenomenon at the population scale to full assess the associated health outcomes. Yet, this reveals a complex task because there exists no consensus indicator of polypharmacy. In fact, the definitions of polypharmacy are heterogeneous and its predisposing factors and associated outcomes are not well defined. The goal of this systematic review is to summarize the literature on polypharmacy in multimorbid individuals aged 65 years and over, targeting three objectives: (1) to identify the definitions of polypharmacy that are used in the context of multimorbidity among older individuals (>= 65 years); (2) to ascertain predisposing and concurrent factors associated with polypharmacy; and (3) to describe positive and negative outcomes of polypharmacy among older individuals, including hospitalizations, mortality and costs. Methods: We will include publications from 2004 to 2016 that target four concepts: polypharmacy, older individuals, multimorbidity and positive/negative outcomes. The search will be performed using EBM Reviews, Embase, Global Health, MEDLINE, AgeLine, CINAHL, Health Policy Reference Center, Public Affairs Index, SocINDEX and Google Scholar. Two independent reviewers will screen the articles, extract the information and evaluate the methodological quality of included studies. The results will be presented in tables and narrative summaries will be performed. We will perform meta-analyses (objective 3) if the heterogeneity is not important. Discussion: This review will help describe the various ways of conceptualizing polypharmacy and how it is associated with health outcomes. We have selected outcomes most relevant for public surveillance performed with administrative databases. Other positive and negative outcomes have been associated with polypharmacy but may not be included in the review. Systematic review registration: PROSPERO CRD42014014989