Investigating polypharmacy and drug burden index in hospitalised older people

Aims: To investigate the changes in polypharmacy and the drug burden index (DBI) occurring during hospitalisation for older people. The secondary aim was to examine the associations of these two measures with the length of hospital stay and admission for falls or delirium. Methods: A retrospective analysis of patients' medical records was undertaken at a large university teaching hospital (Sydney, Australia) for patients with the age of >= 65 years and admitted under the care of the geriatric medicine or rehabilitation teams. Polypharmacy was defined as the use of more than five regular medications. The DBI measures exposure to drugs with anticholinergic and sedative effects. Logistic regression analysis was conducted to investigate the associations between polypharmacy and DBI with outcome measures. Data are presented using odds ratios with 95% confidence intervals. Results: A total of 329 patients was included in this study. The mean (+/- standard deviation) age of the population was 84.6 +/- 7.0 years, 62% were female and 40% were admitted from residential aged-care facilities. On admission, polypharmacy was observed in 60% of the cohort and DBI exposure for 50%. DBI and polypharmacy exposure decreased during hospitalisation, but only the number of medications taken decreased by a statistically significant margin (P = 0.02). Patients with a high DBI (= 1) were approximately three times more likely to be admitted for delirium than those with no DBI exposure (odds ratio, 2.95; 95% confidence interval, 1.34-6.51). Conclusions: In the present study, DBI was associated with an increased risk of hospital admission for delirium only. Polypharmacy was not associated with any of the clinical measures.