Potentially inappropriate medication use in elderly Japanese patients

Background: Modified Beers criteria for elderly Japanese patients were developed in 2008 by consensus among 9 experts to reflect regional clinical practice and available medications in Japan. Since then, many physicians and pharmacists have expressed interest in obtaining more information about the criteria and alternative drug choices.

Objective: This study examined the incidence, health care utilization, and costs associated with potentially inappropriate medications (PIMs) in elderly patients based on the modified Beers criteria.

Methods: A retrospective, observational cohort study was conducted using health insurance claims data in Japan. The study population included elderly patients aged >or=65 years who had at least 2 pharmacy claims in separate months over a 1-year period (April 2006 through March 2007). Use of the PIMs was identified using the modified criteria, and 1-year incidence rates were calculated for the total study population and for subgroups stratified by age and sex. A logistic regression model was used to examine demographic and clinical characteristics associated with PIMs. Health care utilization rates and costs were also analyzed and compared between patients with and without PIMs using generalized linear models. All models included dummy variables indicating age category, female sex, hospitalization, polypharmacy, index month, and number of Elixhauser comorbidities to adjust for potential confounders.

Results: Among 6628 elderly patients, 71.2% (4721/6628) were female and 62.9% (4167/6628) were aged 65 to 74 years; 43.6% (2889/6628) were prescribed at least one PIM. The most commonly used PIMs were histamine-2 blockers (20.5% [1356/6628]), benzodiazepines (11.4% [756/6628]), and anticholinergics and antihistamines (7.9% [526/6628]). No significant differences in incidence rates were observed based on age or sex. Inpatient service use, polypharmacy, and comorbidities of peptic ulcer, depression, and cardiac arrhythmias were significant predictors of PIM use while controlling for other factors. PIM users had significantly higher hospitalization risk (1.68-fold), more outpatient visit days (1.18-fold), and higher medical costs (33% increase) than did nonusers.

Conclusions: In a group of elderly Japanese patients, 43.6% used at least one PIM over a 1-year period in this study. PIM use was associated with greater health care utilization rates and costs.