Factors Associated with Preventability, Predictability, and Severity of Adverse Drug Reactions

OBJECTIVE: To determine the rate of adverse drug reactions (ADRs) in hospitalized patients in an Iranian hospital and to assess factors associated with preventability, predictability, and severity of ADRs. DESIGN AND PARTICIPANTS: A prospective, randomized study was conducted on 370 patients in a hospital at the Tehran Medical Sciences University, from March to December 1996. Patients who experienced at least one ADR (n = 62) were entered into the database. Preventability, predictability, and severity of reactions were determined, based on the available algorithms developed by other investigators. SETTING: A 1200-bed tertiary care university teaching hospital in Tehran, Iran. RESULTS: Approximately 16.8% (n = 62) of the 370 patients who were included in this study had at least one ADR. One hundred two ADRs were reported during this study. Approximately 58.8% of the ADRs (60 reactions) were identified as preventable reactions and 96.1% as predictable reactions. The severity of 9.8% of the ADRs was identified as mild, 86.3% as moderate, 1% as severe, and 2.9% as lethal. The length of hospitalization increased with the severity of the ADRs. Preventable ADRs were more severe than those that were nonpreventable. In addition, the incidence of preventable ADRs increased with the patients' age and caused longer hospitalization than did nonpreventable ones. The most predictable ADRs were hematologic. CONCLUSIONS: This study noted that the rate of ADRs in Iran is probably as high as the rate in other parts of the world. These results indicate a need for a strong national ADR program that detects and reports adverse drug events in Iran.