Association of Polypharmacy and Drug–Drug Interactions with the Development of Adverse Drug Reactions in Multimorbid Hospitalized Patients

Abstract

Multimorbid hospitalized patients are at higher risk of developing drug-drug interactions and adverse drug reactions due to multiple medication administrations. The study aimed to associate polypharmacy and drug–drug interactions (DDI) with the development of adverse drug reactions (ADRs) among multimorbid hospitalized patients. A prospective, cross-sectional design was conducted in the general medicine department of Sri Venkateswara Ramanarayana Ruia Government General Hospital (SVRRGGH), Tirupati, Andhra Pradesh, India. Hospitalized patients who were over 18 years old, had at least two co-morbidities, and were prescribed a minimum of two drugs were eligible for this study. An interview-based data collection tool was used to obtain demographics and clinical profiles for the study participants. The obtained data was used to identify DDIs and ADRs.  A binary and multiple logistic regression analysis used to associate polypharmacy and DDI with the development of ADRs. The polypharmacy was observed in all prescriptions of the participants with an average medication count of 9.52. The prevalence of ADRs and actual and potential DDIs was 29.67%, 10.54% and 89.83%, respectively. The majority of the DDIs were moderate (70.78%) on the severity scale, and ADRs were probable (60.00%) on the causality scale. Factors such as more than three comorbidities (AOR=19.83; 95% CI 1.06-371.28) and the presence of actual DDIs (AOR=1242.51; 95% CI 96.55-15990.23) were significantly associated with the development of ADRs among multimorbid hospitalized patients. Polypharmacy was most common among multimorbid hospitalized patients. Less than one-third of the participants have experienced ADRs, which were significantly associated with multimorbidity and the presence of actual DDIs. Targeted pharmacist interventions based on the factors can reduce the burden of ADRs.