Anticholinergic drugs and functional outcomes in older patients undergoing orthopaedic rehabilitation

Medications with anticholinergic (antimuscarinic) effects negatively affect physical and cognitive function in community-dwelling older patients. However, it is unknown if anticholinergic drugs exert detrimental effects in older patients undergoing rehabilitation.

The purpose of our study was to assess the effect of anticholinergic drug exposure on functional outcomes in older patients undergoing rehabilitation. We speculated that higher anticholinergic drug exposure would be associated with reduced functional outcomes in this group.

Data on clinical characteristics, full medication, anticholinergic drug exposure (total number of anticholinergic drugs [tAD] and Anticholinergic Risk Scale [ARS] score), and Barthel index (BI) score were collected on admission and discharge in a consecutive series of 117 older patients (age 79 [7] years) admitted to the orthopaedic rehabilitation unit of a teaching hospital between July 2010 and March 2011. Outcome measures were BI changes (BI on discharge - BI on admission) during rehabilitation (primary outcome) and length of stay (secondary outcome).

Anticholinergic drugs were prescribed in 38 patients (32.5%). Median and interquartile range for tAD = 0 (0-1); for ARS = 0 (0-1). Poisson regression showed that higher tAD (incidence rate ratio [IRR] = 0.92; 95% CI, 0.88-0.97; P = 0.003) and ARS scores (IRR = 0.97; 95% CI, 0.95-0.99; P = 0.008) on admission independently predicted lower BI changes. Being a woman (IRR = 0.87; 95% CI, 0.78-0.97; P = 0.01), lower Abbreviated Mental Test scores (IRR = 0.94; 95% CI, 0.91-0.97; P < 0.001), and lower BI on admission (IRR = 0.98; 95% CI, 0.97-0.98; P < 0.001), but not tAD or ARS scores, independently predicted increasing length of stay.

Higher anticholinergic drug exposure on admission independently predicts reduced functional outcomes, but not length of stay, in older patients undergoing orthopaedic rehabilitation.