Potentially inappropriate medications among the elderly in primary care in Thailand from three different sets of criteria.

objectiveThe primary objective was to examine potentially inappropriate medications (or PIMs) in the elderly using three different criteria: Beers 2015, STOPP version 2, and Winit-Watjana (for Thai elderly patients). The secondary objective was to examine PIM-related factors.

methodsThis is a retrospective cross-sectional study. Eligible patients were aged ≥65 years in a primary care unit. Demographic data, medical prescriptions in the past year, clinical data and diagnoses were collected from electronic medical records. PIMs, including the use of ≥2 medications, were identified using the three criteria. Descriptive and analytical statistics were conducted. The type I error was 0.05. Multiple logistic regression analysis was used to examine associations between PIMs and other factors.

resultsA total of 400 patients were recruited, and 1,640 prescriptions were reviewed. The median age was 70.5 years, and the median numbers of diseases, medications, and prescriptions were 3 (interquartile range or IQR=2), 11 (IQR=20), and 3 (IQR=4), respectively. Of all the patients, 213 (53.3%) showed a use of ≥5 medications, and 301 (75.3%) were prescribed PIMs. Of the 1,640 prescriptions, 60% had at least one PIM. The Winit-Watjana criteria, Beers 2015 criteria and STOPP version 2 identified 66.8%, 59.0% and 40.3% of the patients receiving PIMs, respectively. Approximately 16% of the patients showed at least one potential drug-drug interaction. The use of duplicate drug classes accounted for the highest proportion of potential drug-drug interactions (41.3%). Polypharmacy (odds ratio or OR 3.93, 95% confidence interval or 95%CI 2.17-71.2) and the presence of ≥4 diseases (OR 2.78, 95%CI 1.39-5.56) were associated with PIMs.

conclusionsPIMs are common among the elderly patients in primary care in Thailand. Prescriptions of the elderly with polypharmacy or multiple concurrent diagnoses should be reviewed for PIMs because they have a high chance of receiving PIMs.