Prevalence and Factors That Influence Potentially Inappropriate Medication Use Among Thai Elderly in Primary Care Settings

Background: Older age increases the likelihood of chronic diseases and polypharmacy with the likelihood of potentially inappropriate medications (PIMs) in secondary and tertiary care levels, but in the primary care settings of Thailand there still is a need for more evidence. This study aimed to examine the prevalence of PIM in primary care settings, and to identify factors that influence the use of PIM.

Methods: A cross-sectional retrospective study was conducted in 2017. Eight primary care units from four regions of Thailand were randomly selected. People aged ≥ 60 years in the eight units were studied as participants. The List of Risk Drugs for Thai Elderly (LRDTE) was used as the reference. Multivariate logistic regression was carried out to identify factors that influence.

Results: A total of 4,848 patients aged ≥60 years with 20,671 prescriptions were studied. The mean age was 70.7±8.3 years for males, and 61.2% for females. A little more than 5% (5.1%) had ≥ 3 chronic diseases and 15.0% received polypharmacy (≥5 medications). The prevalence of prescriptions with PIMs was 65.9%. The most frequent PIMs were antidepressants: amitriptyline (28.1%), antihistamines: dimenhydrinate (22.4%) and chlorpheniramine maleate (CPM) (11.2%); and Benzodiazepines: lorazepam (6.5%). Three factors that significantly influenced prescribing of PIMs were polypharmacy (adjusted OR 3.51; 95% CI 2.81-4.32), having ≥3 chronic diseases (adjusted OR 1.44; 95% CI 1.04-2.01), and age ≥75 years (adjusted OR 1.18; 95% CI 1.01-1.38).

Conclusion: More than two-thirds of elderly Thai patients in the primary care settings were prescribed PIMs. Multidisciplinary prescription review and PIM screening in patients aged ≥75 years who have ≥3 chronic diseases or polypharmacy should be implemented in primary care and supportive computerized PIMs alert system is needed.