An overview of prevalence, determinants and health outcomes of polypharmacy

Abstract

A high rate of polypharmacy is, in part, a consequence of the increasing proportion of multimorbidity in the ageing population worldwide. Our understanding of the potential harm of taking multiple medications in an older, multi-morbid population, who are likely to be on a polypharmacy regime, is limited. This is a narrative literature review that aims to appraise and summarise recent studies published about polypharmacy. We searched MEDLINE using the search terms polypharmacy (and its variations, e.g. multiple prescriptions, inappropriate drug use, etc.) in titles. Systematic reviews and original studies in English published between 2003 and 2018 were included. In this review, we provide current definitions of polypharmacy. We identify the determinants and prevalence of polypharmacy reported in different studies. Finally, we summarise some of the findings regarding the association between polypharmacy and health outcomes in older adults, with a focus on frailty, hospitalisation and mortality. Polypharmacy was most often defined in terms of the number of medications that are being taken by an individual at any given time. Our review showed that the prevalence of polypharmacy varied between 10% to as high as around 90% in different populations. Chronic conditions, demographics, socioeconomics and self-assessed health factors were independent predictors of polypharmacy. Polypharmacy was reported to be associated with various adverse outcomes after adjusting for health conditions. Optimising care for polypharmacy with valid, reliable measures, relevant to all patients, will improve the health outcomes of older adult population.

Keywords: health outcome; multimorbidity; older adults; polypharmacy.

Figure 1.

Determinants and outcomes associated with polypharmacy. Most of the proposed predictors and outcomes of polypharmacy are also independently associated with health conditions. ADR, adverse drug reaction; BMI, body mass index.

Figure 2.

Percentage of patients prescribed 10 or more medicines (excessive polypharmacy) by age group and deprivation in Scotland (obtained from the SIMPATHY consortium document available at http://www.simpathy.eu/).

Figure 3.

Increasing rate of taking prescription medications in the US (obtained from the US prescription drug data for 2007–2008 available at). Significant linear trend from 1999–2000 through 2007–2008. Note: Age adjusted by direct method to the year 2000 projected US population. Source: CDC/NCHS, National Health and Nutrition Examination Survey. CDC, Centers for Disease Control and Prevention; NCHS, National Center for Health Statistics; US, United States.