Associations between different measures of anticholinergic drug exposure and Barthel Index in older hospitalized patients

Objective: To compare associations between four measures of anticholinergic exposure (anticholinergic risk scale, ARS; anticholinergic drug burden, DBAC; number and use versus no use of anticholinergic drugs), Barthel Index (BI, physical function) and Abbreviated Mental Test (AMT, cognitive function) on admission in older hospitalized patients. Methods: Prospective observational study of a consecutive series of 271 older patients (age 83 +/- 7 years) from community-dwelling and institutionalized settings, admitted to an acute geriatric admission unit between 28 September 2011 and 18 December 2011. The main outcome measures were BI quartiles (primary outcome) and AMT (secondary outcome) on admission. Results: Anticholinergic prevalence was 47%. Multinomial logistic regression showed higher DBAC was associated with a greater risk of being in the lower BI quartiles versus highest BI quartile (Q4). This risk was significant for Q3 (p = 0.04) and Q2 (p = 0.02) but not for Q1 (p = 0.06). A greater number of anticholinergic drugs was associated with a higher risk of being in Q2 (p = 0.02). This risk was not significant for either Q3 (p = 0.10) or Q1 (p = 0.06). No significant associations were observed either with use of anticholinergic medication or with ARS and BI quartiles. AMT did not show independent associations with any of the four measures of anticholinergic exposure. Conclusion: In older hospitalized patients, DBAC and some crude measures of anticholinergic exposure, but not ARS, showed independent associations with lower BI, but not AMT. These results highlight differences between various measures of anticholinergic drug exposure when studying their associations with functional status.