Frequency and nature of adverse drug reactions in elderly in-patients of two Indian medical college hospitals

Background: Adverse drug reactions (ADRs) are a major public health problem in the elderly. Although the Indian elderly represent 12.8% of the entire global elderly population, data on prevalence and predictors of ADRs in elderly Indians is extremely limited.
Aim: To determine the prevalence, severity, preventability, length of hospital stays, and risk factors for ADRs in hospitalized Indian elderly.
Setting: Medicine wards of two tertiary care teaching hospitals.
Design: Prospective study was conducted between July 2007 and December 2009.
Materials and Methods: In-patients of either sex and aged ≥60 years were included and monitored for ADRs throughout their hospital stay. Severity (Hartwig et al. scale), preventability (Shumock and Thornton criteria) and increased length of stay (considering underlying disease, ADR, and discussion with clinicians) were assessed.
Statistical Analysis: Bivariate analysis and subsequently multivariate logistic regression were used to determine the risk factors for developing ADRs.
Results: Over the study period, among the 920 patients monitored, 296 patients (32.2%) experienced 419 ADRs. Among all ADRs, 48.4% (203) were preventable. Majority of ADRs [226 (53.9%)] were moderate in severity. Therapeutic classes of drugs frequently associated with ADRs were the drugs used in diabetes [76 (18.1%)] and antibacterials for systemic use [54 (12.9%)]. ADRs increased the hospital stay in 5.9% (54) of patients. Female gender [Odds Ratio: 1.52, 95% Confidence Interval:1.04-2.22, P=0.03] was observed as the influential risk factor for ADRs.
Conclusion: One third of hospitalized elderly experienced ADRs. Interventions focused at preventable ADRs should be developed and implemented to reduce their implications.

Keywords
Adverse drug reaction, aged, geriatrics, India, pharmacovigilance, risk