Polypharmacy and Adverse Drug Reactions in Elderly Patients: A Hospital-Based Cross-Sectional Study

Abstract

Background: Polypharmacy, commonly defined as the concurrent use of five or more medications, is highly prevalent among older adults and is a recognised risk factor for adverse drug reactions (ADRs). Age-related pharmacokinetic and pharmacodynamic changes, multimorbidity, and prescribing cascades compound this risk in the elderly.

Objective: To determine the prevalence of polypharmacy, estimate the frequency and pattern of ADRs, and examine the association between the number of medications and the occurrence of ADRs in hospitalised patients aged 65 years and older.

Methods: A hospital-based cross-sectional observational study was conducted over six months in the medicine department of a tertiary care hospital. A total of 400 patients aged ≥65 years were enrolled by consecutive sampling. Demographic data, comorbidities, and complete medication histories were recorded. ADRs were identified through clinical review and assessed for causality (WHO–UMC scale), severity (Modified Hartwig–Siegel scale), and preventability (Modified Schumock–Thornton criteria). Data were analysed using descriptive statistics and multivariable logistic regression, with p < 0.05 considered significant.

Results: Polypharmacy (5–9 medications) was observed in 52.0% of patients and hyperpolypharmacy (≥10) in 16.0%. At least one ADR was documented in 28.0% of patients, most frequently involving the gastrointestinal (30.4%) and central nervous (23.2%) systems. Cardiovascular agents, NSAIDs, and antidiabetic drugs were the most commonly implicated classes. Compared with patients taking fewer than five medications, the adjusted odds of an ADR rose progressively with 5–9 medications (OR 2.60) and ≥10 medications (OR 6.11).

Conclusion: Polypharmacy is common among hospitalised older adults and is strongly and dose-dependently associated with ADRs, most of which were of moderate severity and potentially preventable. Structured medication review, application of explicit prescribing criteria, and deprescribing initiatives are warranted to improve medication safety in this population.