Drug Burden Index and Its Association With Hip Fracture Among Older Adults: A National Population-Based Study.

BACKGROUND: The Drug Burden Index (DBI) calculates the total sedative and anticholinergic load of prescribed medications and is associated with functional decline and hip fractures in older adults. However, it is unknown if confounding factors influence the relationship between the DBI and hip fractures. The objective of this study was to evaluate the association between the DBI and hip fractures, after correcting for mortality and multiple potential confounding factors. METHODS: A competing-risks regression analysis conducted on a prospectively recruited New Zealand community-dwelling older population who had a standardized (International Resident Assessment Instrument) assessment between September 1, 2012, and October 31, 2015, the study's end date. Outcome measures were survival status and hip fracture, with time-varying DBI exposure derived from 90-day time intervals. The multivariable competing-risks regression model was adjusted for a large number of medical comorbidities and activities of daily living. RESULTS: Among 70,553 adults assessed, 2,249 (3.2%) experienced at least one hip fracture, 20,194 (28.6%) died without experiencing a fracture, and 48,110 (68.2%) survived without a fracture. The mean follow-up time was 14.9 months (range: 1 day, 37.9 months). The overall DBI distribution was highly skewed, with median time-varying DBI exposure ranging from 0.93 (Q1 = 0.0, Q3 = 1.84) to 0.96 (Q1 = 0.0, Q3 = 1.90). DBI was significantly related to fracture incidence in unadjusted (p < .001) and adjusted (p < .001) analyses. The estimated subhazard ratio was 1.52 (95% confidence interval: 1.28-1.81) for those with DBI > 3 compared with those with DBI = 0 in the adjusted analysis. CONCLUSIONS: In this study, increasing DBI was associated with a higher likelihood of fractures after accounting for the competing risk of mortality and adjusting for confounders. The results of this unique study are important in validating the DBI as a guide for medication management and it could help reduce the risk of hip fractures in older adults.

Drug Burden and its Association with Falls Among Older Adults in New Zealand: A National Population Cross-Sectional Study.

BACKGROUND: Adverse outcomes associated with advanced diseases are often exacerbated by polypharmacy. OBJECTIVES: The current study investigated an association between exposure to anticholinergic and sedative medicines and falls in community-dwelling older people, after controlling for potential confounders. METHODS: We conducted a retrospective cross-sectional study of a continuously recruited national cohort of community-dwelling New Zealanders aged 65 years and over. Participants had an International Resident Assessment Instrument-Home Care (interRAI-HC) assessment between 1 September 2012 and 31 January 2016. InterRAI-HC is a comprehensive, multi-domain, standardised assessment. This study captured 18 variables, including fall frequency, from the interRAI. These data were deterministically matched with the Drug Burden Index (DBI) for each participant, derived from an anonymised national dispensed pharmaceuticals database. DBI groupings were statistically ascertained, and ordinal regression models employed. RESULTS: Overall, there were 71,856 participants, with a mean age of 82.7 years (range 65-106); 43,802 (61.0%) were female, and 63,578 (88.5%) were New Zealand European. In unadjusted and adjusted analyses, DBI groupings were related to falls (p < 0.001). A DBI score > 3 was associated with a 41% increase in falls compared with a DBI score of 0 (p < 0.001). There was a 'dose-response' relationship between DBI levels and falls risk. CONCLUSIONS: DBI was found to be independently and positively associated with a greater risk of falls in this cohort after adjustment for 18 known confounders. We suggest that the DBI could be a valuable tool for clinicians to use alongside electronic prescribing to help reduce falls in older people.