Polypharmacy patterns in the last year of life in patients with dementia
Patients with dementia are often treated for multiple co-morbidities. However, little is known about how patterns of prescribing change amongst dementia patients in their last year of life. This study investigated levels of polypharmacy amongst adults who died with dementia, and examined variations by degree of multi-morbidity and dementia sub-type.
A retrospective cohort of 6070 patients who died in the period May 2013 to April 2014 and had a diagnosis of dementia at or before death were identified using anonymised primary care data from the Clinical Practice Research Datalink. Number of drugs (tablets and capsules) prescribed and chronic conditions diagnosed (multi-morbidity) were determined at death, and 2 weeks, 1, 2, 4, 6, 9 and 12 months prior to death. Multi-level negative binomial regression models were used to investigate differences in the number of drugs prescribed by number of chronic diseases and dementia subtype. Models were adjusted for sex, age, number of person-years of registration with the general practice, and clustering by practice.
Average age at death was 86 years (SD=7.3) and 36.3% (n=2203) were men. Patients had an average of 3.7 (SD=2.2) chronic conditions in addition to dementia. 32% and 29% of patients had recorded vascular and Alzheimer’s dementia respectively; dementia subtype was unspecified in 38%. In preliminary analysis, patients were prescribed, on average, 5.0 (95% CI: 4.8-5.1) drugs 12 months prior to death. This increased to 5.5 (5.3-5.6) drugs 2 months prior to death, before decreasing to 4.4 (4.3-4.5) at the time of death. The number of drugs prescribed was 6-fold higher in patients with 6 or more additional multiple chronic conditions than those with dementia only (relative risk 6.1; 5.0-7.3). Patients with Alzheimer’s dementia were prescribed 7% fewer drugs (RR 0.93; 0.88-0.98) compared to those with vascular dementia.
Findings from this study suggest that patients with dementia experience high levels of polypharmacy throughout their last year of life, decreasing only modestly in the last 2 months of life. Greater degrees of multi-morbidity as well as vascular aetiology are associated with greater therapeutic burden. Polypharmacy may be undesirable and pose particular problems to dementia patients due to their complex care needs, with a potentially unfavourable balance of risks and benefits. Understanding current prescribing patterns within this population will help us to identify opportunities for optimising treatment and reducing medication burden in their last year of life.