Kaori, Nomura Drug use patterns and predictors of polypharmacy among elderly, community-residing persons in Hiroshima, Japan from October to December 2009. Kaori Nomura. (Unpublished)
|PDF (Dissertation submitted in partial fulfilment of the requirement for the degree of Master of Public Health, The University of Liverpool. 27 April 2011) |
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Background: Polypharmacy is an established risk factor for adverse drug events (ADEs) resulting from duplication of drugs in the same therapeutic class, drug-drug interactions, contraindicated and other inappropriate medication use. Such ADEs have a major impact the health of users of medicinal products. Japan is a major consumer country of drugs, however, few published studies have examined polypharmacy in Japan. Objectives: To describe the drug use patterns and to identify risk factors for polypharmacy in elderly persons in Hiroshima, Japan. Methods: This is a cross-sectional study, using secondary data of drug utilization in an elderly cohort from Hiroshima, Japan during October through December 2009. Polypharmacy was defined as the concomitant use of five or more drugs (prescription or over-the-counter). Study participants agreed to have all their medications reviewed by the attending pharmacists at participating sites and to provide information, including demographic (age, sex) and underlying diseases. The patterns of drug use were evaluated using descriptive statistics. Stepwise logistic regression models were utilised to identify factors (e.g., age, comorbidities, therapeutic drug class), independently associated with polypharmacy use. Results: A total of 452 persons (median age=76 years, 66% female) were included in this study. Of these paesons, 70% met the definition for polypharmacy (median number of drugs=7, range=5 to 24). The following valriables were significantly associated with polypharmacy use: female sex, comorbidity score (Charlson comorbidity index), and use of at least one medication in certaion therapeutic categories (e.g., antihypertensives, vasodilators, peptic ulcer agents and others). Age and receiving prescriptions from multiple prescribers were not independent predictors of polypharmacy use. Conclusions: Age was not an independent predictor of polypharmacy among elderly people. Prevention strategies for ADEs resulting from polypharmacy should target sicker patients (i.e., comorbidities) and patients receiving care from multiple providers.
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