Evaluation of outpatient adverse drug reactions leading to hospitalization.

Outpatient adverse drug reaction (ADR)related hospitalization through the emergency department of a nonprofit hospital and the contributing factors are reviewed. Patients who were hospitalized because of suspected ADRs were selected from daily admissions reports and patient medication profiles from 1997 and 1998 by the pharmacy department of a nonprofit community teaching hospital. Hospital charges for individual patients were obtained from the institution's accounting system. Suspected drugs, their therapeutic class, and the organ systems involved in the ADRs were identified. A total of 191 patients who had a complete medical history and cost information were included in the study. Of those patients, 56% were female, and 45% of the patients were 75 years of older. The average hospital charge per ADR patient was $9491. Room and board accounted for more than 50% of total charges. The average length of stay for study patients was 8.0 +/- 10.3 days. Major therapeutic classes implicated in ADRs included antidiabetic agents (27.8%), anticoagulants (15.2%), anticonvulsants (10.0%), beta-blockers (7.9%), and angiotensin-converting-enzyme inhibitors (7.9%). Organ systems most commonly involved in ADR admissions were the endocrine (30.9%) and cardiovascular (24.1%) systems. The implicationed therapeutic groups and organ systems exhibited a different pattern from those of earlier ADR studies. The elderly and the poor are most affected by ADRs. The availability of new drugs and the shift in disease treatment necessitate the continuous monitoring of new ADRs. Patients and family members should be integral components of a multidisciplinary strategy for minimizing the personal and social impact of ADRs.