How do non-prescribed medicines (NPMs) contribute to polypharmacy in older adults with multi-morbidity? A systematic review.

Problem

Multi-morbidity (the occurrence of at least two coexisting chronic conditions) is increasingly common among older adults. Multiple medicines (polypharmacy) are often needed to treat multi-morbidity, but there are concerns about the adverse consequences of unnecessary or inappropriate polypharmacy. Most previous research has focused on prescribed medicines, and overlooked the contribution of non-prescribed (NPMs) or over the counter medicines to polypharmacy. This study aims to identify and synthesis current evidence on the use of NPMs by older adults with multimorbidity, generating a working definition of NPMs, determining how common it is, and outlining predisposing factors and outcomes.

Approach

A systematic literature review is underway to address the research questions. A search strategy has been developed to identify relevant articles from electronic databases that include EMBASE, MEDLINE, PsycINFO, CINAHL, AMED, Web of Science and the Cochrane library. The keywords combine terms related to three key concepts - NPMs, multi-morbidity and older adults. Inclusion criteria include articles with populations of older adults (aged 65years and over) with multi-morbidity, exposed to multiple medicines use (both prescribed and NPMs). There are no restrictions on study types, geography and healthcare context/setting. Study selection and screening, data extraction and quality assessment follow established systematic review methods. Analysis and synthesis will be appropriate to the data extracted and will include a narrative overview of included studies as a minimum.

Findings

The systematic review protocol has been developed and registered on PROSPERO (CRD42017077519). Preliminary searches have been undertaken and piloting of the study selection and screening process, data extraction and quality assessment are ongoing. Early findings indicate that there is a large international literature with many observational cross-sectional studies. The terms and concepts related to NPMs are used inconsistently across studies, and in many cases not well-defined. Some of the reported variation in NPM use may be due to inter-study differences in the definitions used and approaches to measurement. Some articles suggest that patients under-report NPM use during their interactions with healthcare professionals. Factors and outcomes associated with NPM use by older adults with multi-morbidity will be outlined and implications considered.

Consequences

There is wide variation in the estimated prevalence of NPMs use by older adults with multi-morbidity. Inconsistencies and inaccuracies in the data captured on NPM may underestimate the true extent of the contribution of NPM to polypharmacy in this population. Exploratory studies would be helpful to understand attitudes and behaviours associated with NPMs from both patients and healthcare professionals’ perspectives.