Adverse drug reactions in United States hospitals.

Adverse drug reactions (ADRs) were examined in 8,208,960 hospitalized Medicare patients in 1998. A database was constructed from the 1998 MedPAR database. The study population was composed of 141,398 Medicare patients who experienced an ADR (rate of 1.73%). The most common drug classes associated with ADRs were cardiotonic glycosides, adrenal corticosteroids, antineoplastic agents, anticoagulants, and analgesics. The most common associated diagnoses were hypertension, congestive heart failure, atrial fibrillation, volume depletion disorders, and atherosclerotic heart disease. In patients who experienced an ADR, death rates were 19.18% higher with 1971 excess deaths (odds ratio 1.208, 95% confidence interval 1.184-1.234), and length of hospital stay was 8.25% higher with 77,769 excess patient-days (Mann-Whitney U test [U]=200078720610, p<0.0001). Charges for patients with an ADR were increased as follows: total Medicare 19.86% (339,496,598 US dollars, U=200,089,611,739, p<0.0001), drugs 9.15% (24,744,650 US dollars, U=208,719,928,502, p<0.0001), and laboratory charges 2.82% (6,221,512 US dollars, U=195,143,498,450, p<0.0001). We developed a list of high-risk diagnoses and drug classes to help pharmacists target patients who are more likely to experience ADRs. This is the first study to evaluate the ADRs in a large population of hospitalized Medicare patients. These findings will enable pharmacists to develop better management programs for ADRs.