Objectives: To determine the cognitive and functional consequences of dual use of cholinesterase inhibitors (ChIs) and the bladder anticholinergics oxybutynin or tolterodine.
Design: Prospective cohort study.
Setting: Nursing homes (NHs) in the state of Indiana.
Participants: Three thousand five hundred thirty-six Medicaid-eligible NH residents aged 65 and older taking a ChI between January 1, 2003, and December 31, 2004. Residents were excluded if they were taking an anticholinergic other than oxybutynin or tolterodine.
Measurements: Indiana Medicaid claims data were merged with data from the Minimum Data Set (MDS). Repeated-measures analyses were performed to assess the effects of dual therapy on change in cognitive function measured using the MDS Cognition Scale (MDS-COGS; scored 0-10) and change in activity of daily living (ADL) function using the seven ADL items in the MDS (scored 0-28). Potential covariates included age, sex, race, number of medications, and Charlson Comorbidity Index score.
Results: Three hundred seventy-six (10.6%) residents were prescribed oxybutynin or tolterodine concomitantly with a ChI. In residents in the top quartile of ADL function, ADL function declined an average of 1.08 points per quarter when not taking bladder anticholinergics (ChI alone), compared with 1.62 points per quarter when taking dual therapy, a 50% greater rate in quarterly decline in ADL function (P=.01). There was no excess decline attributable to dual therapy in MDS-COGS scores or in ADL function for residents who started out with lower functioning.
Conclusion: In higher-functioning NH residents, dual use of ChIs and bladder anticholinergics may result in greater rates of functional decline than use of ChIs alone. The MDS-COGS may not be sensitive enough to detect differences in cognition due to dual use.