Medicines use and polypharmacy in retirement village residents in Aotearoa New Zealand: a point prevalence observational study

Introduction

Polypharmacy (the prescription of five or more medicines¹) and hyperpolypharmacy (10 or more regular medicines²) are associated with increased risk of adverse drug reactions (ADRs) in older age.³ The impact of ADRs may be more significant in older adults, with higher risk of resultant morbidity including impaired physical function.⁴

Retirement villages (RVs) are an increasingly popular housing option for older adults, with 14% of those aged 75-plus years in New Zealand (NZ) residing in them.⁵ The number of older adults living in RVs is predicted to rise due to the ageing population⁵ and other perceived social and health benefits including increased security, reduced loneliness and the presence of onsite health clinics.⁶ Although there is evidence to show polypharmacy increases falls risk in the community and aged residential care settings,^7,8 little is known about polypharmacy, or medicine use more generally, in the RV setting.

We aimed to describe medicine use and the point prevalence of polypharmacy among RV residents.

Methods

Results

In total, 578 residents from 33 RVs were recruited (72.7% female, median age 81.6 years (interquartile range 76.4–86.6)). Almost all participants self-reported European ethnicity (n = 558; 96.5%), with other ethnicities including Asian (n = 8; 1.4%), Māori (n = 7; 1.2%) and Pacific peoples (n = 1; 0.02%). The sociodemographic and health profiles of residents recruited are available elsewhere.¹¹

Participants were taking a mean of 4.8 regular medicines (range = 0–13; s.d. = 2.9), and 0.7 ‘as required’ medicines (range = 0–6; s.d. = 1.0). Age and gender were not statistically significantly associated with number of medicines or the proportion with polypharmacy/hyperpolypharmacy (Supplementary Table S2).

The most common medicine class was antihypertensive followed by lipid- lowering (Table 1). Lipid-lowering therapy and antiplatelet therapy were used for primary prevention of cardiovascular disease (ie no history of cardiovascular disease) in 29.6% and 21.4% of cases, respectively (Supplementary Table S3). Regular analgesics were taken by 16.1% of the participants, with a further 13.3% having taken an ‘as required’ analgesic in the 72 h prior to assessment.

Discussion

This is the first large-scale study of medicine use and polypharmacy in RV residents in NZ. The prevalence of polypharmacy in our study was not significantly different between age groups, in contrast to the general NZ older adult population where polypharmacy rates increase linearly across the age ranges.¹² This finding suggests RV residents may have similar medicine-related needs as a cohort, independent of age, compared to community-dwelling older adults.¹² The prevalence of polypharmacy in our study was higher than that for the general NZ population of a similar age (51.2% compared to 41.9%, respectively¹²), but closer to Australian RV data (51.2 and 46.7%, respectively¹³). The higher prevalence of polypharmacy in RV residents means they may be at more risk of ADRs and have greater need for medicines-related support than the general older adult population, which is supported by other research demonstrating high levels of unmet health needs in RV residents.¹¹ Polypharmacy may, however, be appropriate to treat multiple long-term conditions and hence there is ever increasing attention paid to the concept of ‘inappropriate’ polypharmacy, whereby medicines are prescribed in excess of therapeutic need, or in ways that are harmful.¹⁴ There are a number of medicine classes that are known to increase the risk of adverse drug events in older people, including hypnotics, antipsychotics, hypoglycaemics and anticoagulants,¹⁵ which all featured in our current study. Hypnotics are associated with increased risk of confusion, muscle weakness, and falls, which impact older people to a greater extent than younger people, and in our study, these were prescribed at similar rates as those seen in the general 75+ years population in NZ.¹⁶ Combinations of medicines, such as a non-steroidal anti-inflammatory drug in combination with a diuretic and ACE inhibitor/angiotensin receptor blockers, otherwise known as the ‘triple whammy’, also increase the risk of adverse outcome. The 'triple whammy' was presented in just over 1% of our study cohort and, although the numbers are low, there is significant risk of acute kidney injury with the concomitant use of these medicines¹⁷ and these should be avoided wherever possible. In contrast, some medicine classes such as proton pump inhibitors, which were used by 37.4% of our study population, can cause adverse effects from chronic use.¹⁵ Prolonged use of proton pump inhibitors in older people can increase the risk of osteoporotic fractures, cause vitamin B12 deficiency and increase the risk of community-acquired pneumonia and Clostridium difficile infection,¹⁸ and regular review is required to prevent ongoing inappropriate use. The complex nature of medicine use in older age highlights the need for medicine reviews. These should be undertaken on an individual basis to understand the clinical and social contexts in which medicines have been prescribed, and therefore whether medicines are appropriate for that individual.

Statins have been shown to increase all-cause mortality when used for primary prevention of cardiovascular disease in older people (65–74 years),¹⁹ which is particularly relevant in our study where almost one-third of residents were taking a statin for primary prevention. Recommendations to stop aspirin for primary cardiovascular prevention and to stop statins for primary cardiovascular prevention in persons aged >85 years and those with frailty with a life expectancy <3 years has been added to the newly updated Screening tool of older people's prescriptions (STOPP) and screening tool to alert to right treatment (START) criteria, an internationally recognised screening tool for appropriate prescribing in older adults.¹⁵ The use of statins for primary prevention in older people remains a contested topic,²⁰ particularly when employing an explicit age cut-off, and needs to be reviewed on an individual basis. Our recently published study described changes to medicines made as part of a randomised controlled trial of a comprehensive multidisciplinary team review in the retirement village setting.²¹ We identified that <40% of recommended medicine changes aligned with STOPP/START criteria,¹⁵ highlighting the need for medicine reviews with RV residents to take into account the context of their individual co-morbidities, prognosis and goals.

Conclusion

Hyperpolypharmacy and cardiovascular medicines for primary prevention, as well as other known high-risk medicines, provide potential targets for further investigation to improve the health outcomes for people living in RVs, particularly in the case of high rates of statin use for primary prevention of cardiovascular disease in this cohort.

Supplementary material

Supplementary material is available online.