Singapore’s ageing population and growing burden of chronic disease are seen to propel the prevalence of polypharmacy, which has been shown to be significantly associated with age and type of care setting, according to a study.
“Polypharmacy is associated with increased prevalence of potentially inappropriate medications (PIMs), leading to higher risk of adverse drug events and medication errors,” said the researchers, who retrospectively reviewed prescriptions on two randomly selected days from five acute care hospitals and primary care polyclinics in Singapore.
Patients’ demographic characteristics, number of prescription line items, and details of prescribed drugs were obtained. The Beers Criteria were used to identify PIMs and subsequently assess prescribing appropriateness. The research team then explored the relationship of demographics and type of care setting with polypharmacy and PIM use using logistic regression.
Hospitals recorded a significantly higher prevalence of polypharmacy than polyclinics (66.6 percent vs 35.0 percent; p<0.001). On the other hand, PIM prevalence among older adults with polypharmacy was significantly higher in polyclinics than in hospitals (34.6 percent vs 27.1 percent; p=0.010). [Singapore Med J 2026;67:544-551]
Hospitalized patients and those aged ≥65 years were more likely to have polypharmacy than patients in polyclinics and those aged 21‒64 years. The drugs used for chronic conditions were a significant factor in having polypharmacy in both care settings. Specifically, medications for functional gastrointestinal disorders and systemic antihistamines were the leading PIMs in hospitals and polyclinics, respectively.
Multimorbidity
Previous studies have reported the association between polypharmacy and multimorbidity, which tends to increase with age and add to financial burden in primary care. [Ann Acad Med Singap 2021;50:809-817; Front Pharmacol 2020;11:326; BMC Public Health 2021;21:1409]
“All the local studies, including our current research, defined polypharmacy as the use of five or more medications, although the counting methods varied due to a lack of consensus in the definition and research methodology,” the researchers said. [BMC Geriatr 2017;17:230]
Two local studies examined PIM prevalence in their institutions and found higher prevalence among Singapore nursing home residents (70.04 percent), driven primarily by the “lack of documentation of clinical indication” for the medications used. [Ann Acad Med Singap 2004;33:49-52]
“Meanwhile, the prevalence of PIMs among hospital patients in our study (27.1 percent) was comparable to that found in geriatric inpatients during their hospital stay (27.6 percent),” the researchers said. [Singapore Med J 2019;60:298-302]
Cardiovascular diseases
In both hospitals and polyclinics, chronic medications used to treat cardiovascular diseases and manage related risk factors often promote to having polypharmacy, according to the researchers.
“It reflects the high prevalence of these conditions in Singapore and may be a result of clinical guideline-directed management using drug combinations or physicians’/patients’ desire to achieve better control of disease indicators,” they said. [https://www.moh.gov.sg/resources-statistics/singapore-health-facts/disease-burden; https://www.moh.gov.sg/resources-statistics/singapore-health-facts/top-10-conditions-of-hospitalisation]
“Given the magnitude of polypharmacy and PIM use in Singapore, our ageing population and increasing chronic disease burden, more focus should be placed on ensuring appropriate polypharmacy, and this study can inform nationwide deprescribing efforts and allow development of tailored strategies for vulnerable groups,” the researchers said.
Polypharmacy has been shown to increase medication nonadherence, adverse drug events, and the risk of death. [Drugs Aging 2004;21:793-811; Expert Opin Drug Saf 2014;13:57-65; Expert Opin Drug Saf 2014;13:57-65; Arch Gerontol Geriatr 2022;100:104630]