Potentially inappropriate medication use in elderly patients: A study of prevalence and predictors in two teaching hospitals

Background: Geriatrics is an emerging clinical specialty in India. Information about the appropriateness of prescription medication use among the elderly in India is limited. Aims: To determine the prevalence and predictors of potentially inappropriate medication (PIM) use, and assess the relationship between PIM use and adverse drug reactions (ADRs) in the hospitalized elderly. Settings: Medicine wards at two teaching hospitals. Design: Prospective observational study. Materials and Methods: Patients aged >= 60 years admitted to medicine wards between January 2008 and June 2009 were included and reviewed for PIM use according to the Beers Criteria 2003 (BC). Severity of PIM use was classified as per BC as 'high' or 'low'. ADRs observed in the study patients were also recorded. Statistical Analysis: Association between ADRs and PIM use was assessed using Chi Square test. Bivariate analysis and subsequently multivariate logistic regression was used to identify predictors of PIM use. Results: PIM use was observed in 191 of 814 enrolled patients. At least one PIM at admission and during hospital stay was received by 2.4% (20) and 22.1% (180) patients respectively. High-severity PIM use showed a higher prevalence compared to low severity [26.8% (218) vs. 5.5% (45)]. Amongst the patients who received polypharmacy (>= 5 concurrent medications), 1.4% (5/362) and 22.1% (163/736) patients received PIMs at admission and during hospital stay respectively. Use of aspirin/clopidogrel/diclofenac in the presence of blood clotting disorder or anticoagulant therapy (8.3%) was the most commonly encountered PIM use. Medications not listed in BC were associated with increased occurrence of ADRs compared to medications listed in BC (349 vs. 11) (chi(2)=98.4, P < 0.001). Increased number of concurrent medications' use (>= 9) during the stay in medicine wards was identified as an influential predictor of PIM use [Odds ratio: 1.9, 95% Confidence Interval: 1.34-2.69, P < 0.001) in the hospitalized elderly. Conclusion: PIM use was common (23.5%) among the elderly patients during their stay in medicine wards in two tertiary care hospitals. Measures targeted only at BC medications may do little to change the risk of ADRs in elderly.