Drug Burden Index and physical function in older Australian men

Abstract

Aims: This study evaluated the associations of physical performance and functional status measures with the Drug Burden Index in older Australian men. The Drug Burden Index is a measure of total exposure to anticholinergic and sedative medications that incorporates the principles of dose-response and maximal effect.

Methods: A cross-sectional survey was performed on community-dwelling older men enrolled in The Concord Health and Ageing in Men Project, Sydney, Australia. Outcomes included chair stands, walking speed over 6 m, 20-cm narrow walk speed, balance, grip strength and Instrumental Activities of Daily Living score (IADLs).

Results: The study population consisted of 1705 men (age 76.9 +/- 5.5 years). Of the 1527 (90%) participants who reported taking medications, 21% were exposed to anticholinergic and 13% to sedative drugs. The average Drug Burden Index in the study population was 0.18 +/- 0.35. After adjusting for confounders (sociodemographics, comorbidities, cognitive impairment, depression), Drug Burden Index was associated with slower walking speed (P < 0.05), slower narrow walk speed (P < 0.05), balance difficulty (P < 0.01), grip weakness (P < 0.01) and poorer performance on IADLs (P < 0.05). Associations with physical performance and function were stronger for the sedative than for the anticholinergic component of the Drug Burden Index.

Conclusions: Higher Drug Burden Index is associated with poorer physical performance and functional status in community-dwelling older Australian men. The Drug Burden Index has broad applicability as a tool for assessing the impact of medications on functions that determine independence in older people.

Figure 1

Analysis of covariance for the association of adjusted means of physical performance measures, grip strength and functional status with increasing Drug Burden Index. Means adjusted for age, education, comorbidities, body mass index (BMI), history of falls, cognitive impairment and depression. Drug Burden Index grouped into three intervals (0, 0–1, ≥1). Error bars show 95% confidence interval (CI). IADL, Instrumental activities of daily living; IADL score – higher score indicates worse function, balance test, 0-worst performance, 3-best performance; grip strength – higher number indicates better function; chair stands, 6 m walking speed and 20-cm narrow walking speed, lower number indicates better performance