Associations between the anticholinergic risk scale score and physical function: potential implications for adverse outcomes in older hospitalized patients

Abstract

Objectives: The anticholinergic risk scale (ARS) score is associated with the number of anticholinergic side effects in older outpatients. We tested the hypothesis that high ARS scores are negatively associated with "global" parameters of physical function (Barthel Index, primary outcome) and predict length of stay and in-hospital mortality (secondary outcomes) in older hospitalized patients.

Design and setting: Prospective study in 2 acute geriatric units.

Participants: Three hundred sixty-two consecutive patients (age 83.6 ± 6.6 years) admitted between February 1, 2010, and June 30, 2010.

Measurements: Clinical and demographic characteristics, Barthel Index, full medication exposure, and ARS score were recorded on admission. Data on length of stay and in-hospital mortality were obtained from electronic records.

Results: After adjustment for age, gender, dementia, institutionalization, Charlson Comorbidity Index, admission site, and number of nonanticholinergic drugs, a unit increase in ARS score was associated with a 29% reduction in the odds of being in a higher Barthel quartile than a lower quartile (odds ratio 0.71, 95% confidence interval [CI] 0.59-0.86, P = .001). The Barthel components mostly affected were bathing (P < .001), grooming (P < .001), dressing (P < .001), transfers (P =.005), mobility (P < .001), and stairs (P < .001). Higher ARS scores predicted in-hospital mortality among patients with hyponatremia (hazard ratio [HR] 3.66, 95% CI 1.70-7.89, P = .001) but not those without hyponatremia (HR 1.04, 95% CI 0.70-1.54, P = .86). The ARS score did not significantly predict length of stay (HR 1.02, 95% CI 0.88-1.17, P = .82).

Conclusion: High ARS scores are negatively associated with various components of the Barthel Index and predict in-hospital mortality in the presence of hyponatremia among older patients. The ARS score may be useful in the acute setting to improve risk stratification.