To examine the risk of dementia with anticholinergic use among elderly nursing home residents with depression.
Population-based nested case-control study.
Population-based study involving 2007-2010 Minimum Data Set-linked Medicare data from all 50 states.
Medicare beneficiaries aged 65 years and older, diagnosed with depression, and no history of dementia as of 2007 (baseline period). Cases were identified as patients with incident dementia following the baseline period. For each case, four age- and sex-matched control subjects were selected using incidence density sampling.
Anticholinergic exposure was defined using Anticholinergic Drug Scale. Prescription of clinically significant anticholinergic medications (levels 2 and 3) 30 days preceding the event date formed the primary exposure. The primary outcome was dementia diagnosis, between January 1, 2008, and December 31, 2010. A conditional logistic regression model stratified on matched case-control sets was performed to assess dementia risk, after controlling for other risk factors.
The study sample included 28,388 cases diagnosed with dementia and 113,352 matched control subjects. After adjusting for other risk factors, clinically significant anticholinergic use was associated with significant risk of dementia (OR: 1.26; 95% CI: 1.22-1.29) compared with non-use. The findings remained consistent across levels of anticholinergic potency (level 2, OR: 1.37, 95% CI: 1.31-1.44; level 3, OR: 1.15, 95% CI: 1.10-1.19).
Use of clinically significant anticholinergic medications was associated with a 26% increase in risk of dementia among elderly nursing home residents with depression. With increasing safety concerns, there is a significant need to optimize anticholinergic use, especially for those who are at risk for dementia.