How Chronic Is Polypharmacy in Old Age?

A Longitudinal Nationwide Cohort Study

Jonas W. Wastesson, PhD; Lucas Morin, MSc; Marie-Laure Laroche, PhD; Kristina Johnell, PhD

Disclosures

J Am Geriatr Soc. 2019;67(3):455-462. 

In This Article

Abstract and Introduction

Abstract

Objective: To evaluate the chronicity of polypharmacy among older adults and to identify factors associated with chronic polypharmacy.

Design: Longitudinal cohort study using register data.

Setting: Nationwide, Sweden.

Participants: All 711,432 older adults (aged 65 years and older) living in Sweden with five or more prescription drugs in October 2010 were included and followed up until December 2013. Mean age at baseline was 77 (SD = 7.8) years, 59% were women, and 7% lived in nursing homes.

Measurement: Monthly changes in the exposure to polypharmacy. Data regarding prescription drug use were extracted from the Swedish Prescribed Drugs Register.

Results: Overall, 82% were continuously exposed to polypharmacy for 6 months or longer, and 74% for 12 months or longer. The proportion of individuals who remained exposed until the end of the study was 55%. Among the 21,361 individuals who had not been exposed to polypharmacy during the 6-month period before baseline (ie, with a new episode of polypharmacy), only 30% remained exposed for 6 months or longer. The proportion of older adults who spent at least 80% of their follow-up time with polypharmacy was substantially higher among prevalent polypharmacy users at baseline than among those with a new polypharmacy episode (80% vs 24%; P < .01). Factors associated with chronic polypharmacy included higher age, female sex, living in an institution, chronic multimorbidity, and multidose dispensing.

Conclusion: Polypharmacy is most often chronic, although a substantial share of older adults experience short, recurring episodes of polypharmacy and are thus exposed to its potential harms in a transient rather than persistent manner.

Introduction

Multimorbidity is common among older adults and often results in multiple medication use. Polypharmacy (commonly defined as the concurrent use of five or more drugs)[1] is a concern because it has been linked to an array of negative health outcomes.[2–6] The prevalence of polypharmacy has increased in most countries during the last decades.[7–11] In the United States, it is estimated that about 40% of people aged 65 years or older use five or more drugs concomitantly.[7] Yet, few studies have documented the longitudinal development of polypharmacy over time, and little is known about the proportion of older adults who are chronically exposed to polypharmacy. Prior studies suggest that older adults tend to persist with polypharmacy over time.[12–16] Factors such as higher age, female sex, high body mass index, smoking, and chronic conditions are associated with higher odds of remaining on polypharmacy.[16] However, these studies were based on survey data with several years between each wave. The use of prescription drugs by older adults can fluctuate, and episodes of polypharmacy can occur sporadically. Newly diagnosed chronic conditions and temporary changes in health status (eg, postoperative pain, infections) can, for instance, prompt an increase in the number of drugs, while deprescribing and lack of adherence can shorten the medication list.

Understanding the chronicity of polypharmacy is important for a number of reasons.[17] First, most definitions of polypharmacy do not consider whether the exposure to polypharmacy is chronic or transient.[18,19] Yet, this has implications for evaluating the quality of drug prescribing since short-term exposure to polypharmacy as a response to acute events is often clinically appropriate. Second, various interventions have been implemented to reduce the prevalence and the harms of polypharmacy. Most of these interventions have proven unsuccessful.[20,21] Polypharmacy may not always be a chronic and persistent hazard,[22] making it difficult to provide tailored interventions at the right time for older adults.[18] Third, observational studies aiming at establishing a causal association between polypharmacy and subsequent health outcomes have seldom considered polypharmacy as a time-varying or cumulative exposure based on the assumption that polypharmacy is by definition chronic.[23] Yet, until now, this assumption has remained untested and there exists no consensual definition of what constitutes chronic polypharmacy.[19] Our aim was thus twofold: (i) to evaluate the degree of chronicity of polypharmacy among older adults in Sweden and (ii) to identify factors associated with chronic rather than transient polypharmacy.

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