Aim: This study assessed medication use patterns and polypharmacy in patients who were admitted through an acute assessment unit (AAU) and stratified results according to patient age. This study also examined risk factors associated with polypharmacy and consequences of polypharmacy, namely prescription writing errors, drug-drug interaction and geriatric syndrome.
Methods: The medication charts and admission notes of 200 consecutive patients admitted through the AAU over a period of 1 month were retrospectively reviewed. Data were collected on patients' demographics, comorbidities, types and number of medications, hospital length of stay and reason(s) for presentation. Potentially harmful prescription errors or errors necessitating intervention were also recorded, as were any potential adverse drug-drug interactions.
Results: Medications for the treatment of disorders of the cardiovascular (46% of total patients) and nervous systems (30%) predominated. Of the 200 patients reviewed, 158 were aged ≥ 65 years and their mean serum creatinine was higher than those aged < 65 years (100.9 ± 54.0 vs. 79.9 ± 45.9 µmol/L, P = 0.01), 81% were taking five or more concurrent regular medications at the time of admission. Of all 200 patients, 28% suffered renal impairment, defined as creatinine > 100 µmol/L for women and > 120 µmol/L for men. The presence of more than two comorbidities (odds ratio (OR) 6.80; 95% confidence interval (CI) 2.89-16.00; P < 0.001) and age (OR 2.91; 95% CI 1.24-6.80; P = 0.01), were factors associated with polypharmacy. Excessive polypharmacy was associated with an increased risk of prescription errors that could cause temporary harm or required intervention (OR 5.23; 95% CI 1.39, 19.69; P = 0.009) but was not associated with a prolonged length of stay.
Conclusions: This study showed that polypharmacy and renal impairment are prevalent amongst elderly patients admitted through an AAU. Polypharmacy in the elderly is attributable to greater comorbidities and is associated with an increased risk of adverse consequences. To avoid inappropriate medication use and improve the quality of prescription among those with polypharmacy, careful review of elderly patients' drugs is needed while they are in the AAU.
© 2011 Japan Geriatrics Society.