Associations of drug burden index with falls, general practitioner visits, and mortality in older people

Aim: On a population level in people aged ≥65years old living in New Zealand, the aim of this study is to quantify each individual's cumulative exposure to anticholinergic and sedative medicines using the Drug Burden Index (DBI) and examine the impact of DBI on fall-related hospitalisations, general practitioner (GP) visits, and all-cause mortality. 

Method: The study used data extracted from Pharmaceutical Claims Data Mart (2011), National Minimum Data set (2012), Births, Death and Marriages (2012) and GP Visits (2012) for patient demographics, hospitalisations and mortality. Cumulative anticholinergic and sedative exposure was measured using the DBI. Polypharmacy was defined as greater than or equal to five medicines dispensed concurrently at any time during the study period. 

Results: Amongst the study population (n=537387; 45% male), 43.22% were exposed to DBI drugs (95% confidence intervals (CIs)=43.09-43.35). The odds of DBI exposure for individuals with polypharmacy are 4.92 (95%CI=4.86-4.98) times greater than that for individuals without polypharmacy. DBI drugs were associated with fall-related hospitalisations (incidence rate ratio (IRR) 1.56, 95%CI=1.47-1.65) and greater number of GP visits (IRR 1.13, 95%CI=1.12-1.13). Individuals with DBI>0 had a 1.29 times higher mortality risk (95%CI=1.25-1.33). Polypharmacy is also associated with a higher mortality risk with a hazard ratio (HR) of 1.66 (95%CI=1.59-1.73).

Conclusion: Polypharmacy and exposure to DBI drugs were independently associated with fall-related hospitalisations, frequency of GP visits, and risk of mortality. On a population level, DBI may be useful as a quality indicator to guide policy to improve prescribing and optimize clinical outcomes in older people.