Elsevier

Experimental Gerontology

Volume 106, June 2018, Pages 240-245
Experimental Gerontology

Polypharmacy in people with dementia: Associations with adverse health outcomes

https://doi.org/10.1016/j.exger.2018.02.011Get rights and content

Highlights

  • Polypharmacy in patients with dementia is associated with an increased risk of emergency department attendance, hospitalisation and death.

  • Risk of any or unplanned hospitalisation is increased by 12% in those taking 4-6 medications.

  • A dose-response relationship exists between the number of medications at dementia diagnosis and adverse health outcomes.

Abstract

Polypharmacy has been linked to higher risks of hospitalisation and death in community samples. It is commonly present in people with dementia but these risks have rarely been studied in this population. We aimed to investigate associations between polypharmacy and emergency department attendance, any and unplanned hospitalisation, and mortality in patients with dementia. Using a large mental health care database in South London, linked to hospitalisation and mortality data, we assembled a retrospective cohort of patients diagnosed with dementia. We ascertained number of medications prescribed at the time of dementia diagnosis and conducted multivariate Cox regression analyses. Of 4668 patients with dementia identified, 1128 (24.2%) were prescribed 4–6 medications and 739 (15.8%) ≥7 medications. Compared to those using 0–3 medications, patients with dementia using 4–6 or ≥7 agents had an increased risk of emergency department attendance (hazard ratio 1.20/1.35), hospitalisation (hazard ratio 1.12/1.32), unplanned hospital admission (hazard ratio 1.12/1.25), and death within two years (hazard ratio 1.29/1.39) after controlling for potential confounders. We found evidence of a dose response relationship with each additional drug at baseline increasing the risk of emergency department attendance and mortality by 5% and hospitalisation by 3%. In conclusion, polypharmacy at dementia diagnosis is associated with a higher risk of adverse health outcomes. Future research is required to elucidate which specific agents underlie this relationship and if reduction of inappropriate prescribing is effective in preventing these outcomes in dementia.

Introduction

Compared to the general older population, people with dementia have high rates of physical and psychiatric co-morbidity, often resulting in the prescription of multiple medications simultaneously (Andersen et al., 2011; Clague et al., 2017). Clinical practice guidelines and policies tend to provide advice for single conditions, such as dementia or cardiovascular disease, and their applicability to patients with multiple co-morbidities is often unclear. Individual medications, which are beneficial and well-evaluated in a single condition, may lose their effect or even be harmful when taken in combination with other medications, due to drug-drug interactions, and little evidence exists on the efficacy, safety and tolerability of medications used to manage co-morbidities in dementia (Duerden et al., 2013; Reeve et al., 2015). People with dementia are often excluded from clinical trials, from which guideline-based treatments for long-term conditions commonly arise (Brauner et al., 2000; Parsons, 2017). Further, typical dementia symptoms, such as declining memory, executive dysfunction, language problems and agitation might prevent adverse drug events from being detected early and before they lead to more serious complications and subsequent hospitalisation (Onder et al., 2011).

In community samples of older people, polypharmacy has been linked to inappropriate prescribing (Guthrie et al., 2011), adverse drug events (Bourgeois et al., 2010), preventable and unplanned hospitalisation (Leendertse et al., 2008; Payne et al., 2014), increased mortality (Gnjidic et al., 2012; Richardson et al., 2011), reduced adherence (Vik et al., 2004), higher risk of falls (Richardson et al., 2015) and frailty (Veronese et al., 2017), and impaired quality of life (Fincke et al., 1998). However, despite the reported high levels of polypharmacy in people with dementia very little is known about potential adverse health outcomes in this group (Parsons, 2017), apart from one study of nursing home residents with severe dementia, in whom the prescription of 10 or more medications was associated with a higher mortality risk (Onder et al., 2013).

We sought to investigate if polypharmacy is associated with four important outcomes – emergency department attendance, any and unplanned hospital admissions, and mortality – in a large, naturalistic sample of people with dementia.

Section snippets

Data source

Data were obtained from the South London and Maudsley NHS Foundation Trust (SLaM) Clinical Record Interactive Search (CRIS) application. SLaM is one of Europe's largest healthcare providers for dementia and other mental disorders, serving a population of over 1.2 million residents, and has adopted fully-electronic health records for all services since 2006. CRIS provides research access to >300.000 de-identified health records from SLaM within a robust governance framework (Perera et al., 2016;

Results

We identified 6253 patients diagnosed with dementia in SLaM outpatient services within the observation period. After excluding 413 (6.6%) patients who were under the age of 65 at the time of dementia diagnosis, 909 (14.5%) without recorded MMSE score and 262 (4.2%) lacking information on physical health, the sample consisted of 4668 patients.

Of these, 64.2% were female and 18.2% from a minority ethnic group. Mean age at dementia diagnosis was 81.7 (SD ±6.9) years. Mean MMSE score was in the

Discussion

In this study of >4000 patients diagnosed in a specialist dementia care and assessment provider we demonstrated that polypharmacy is associated with an increased risk of emergency department attendance, and both any and unplanned hospitalisation, as well as mortality over a two-year follow-up period. We further demonstrated a dose-response relationship between number of medications prescribed and negative outcomes.

Hospitalisation is a common and unwanted event for people with dementia (Rao et

Funding

The Clinical Records Interactive Search (CRIS) system was funded and developed by the National Institute for Health Research (NIHR) Mental Health Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London, and by a joint infrastructure grant from Guy's and St Thomas' Charity and the Maudsley Charity. CM and RS authors receive salary support from the National Institute for Health Research (NIHR) Mental Health Biomedical Research Centre at South London

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