Assessing Medication Use Quality in Older Outpatients Using the Beers Criteria: Findings from a Single-Center Retrospective Study

BACKGROUND: No comprehensive assessment of the quality of medications used in older outpatients has been conducted in Thailand. This study aimed to ascertain the prevalence of and factors contributing to older outpatients' use of potentially inappropriate medications (PIMs). METHODS: This cross-sectional study retrospectively assessed the prescriptions of older (≥60 years) outpatients at a secondary-care hospital. For PIM identification, the 2019 American Geriatric Society (AGS) Beers criteria were applied, considering all five PIM categories: PIM category I (medications that are potentially inappropriate in most older adults), II (disease-/syndrome-exacerbating drugs), III (medications that should be used with caution), IV (clinically important drug–drug interactions), and V (medications that should be avoided or have their dosage reduced based on renal function). RESULTS: This study included 22,099 patients (mean age, 68.86±7.64 years). Nearly three-fourths of patients were prescribed PIMs, with 68.90%, 7.68%, 44.23%, 15.66%, and 3.05%, respectively, receiving category I–V medications. The positive factors associated with PIM use included female sex (odds ratio [OR]=1.08; 95% confidence interval [CI], 1.01–1.16), age ≥75 years (OR=1.10; 95% CI, 1.01–1.21), polypharmacy (OR=10.21; 95% CI, 9.31–11.21), ≥3 diagnostic categories (OR=2.31; 95% CI, 2.14–2.50), and ≥3 chronic morbidities (OR=1.46; 95% CI, 1.26–1.68). The negative factor associated with PIM use was a comorbidity score of ≥1 (OR=0.78; 95% CI, 0.71–0.86). CONCLUSION: PIM use among older outpatients remains highly prevalent in clinical practice. The results of this study identified polypharmacy as the strongest factor affecting PIM use.