Adverse drug reaction reporting in a multicenter surveillance study

OBJECTIVE: To evaluate the performance of a multicenter, prospective surveillance program in identifying adverse events, and to seek explanations for misclassification bias. DESIGN: The design was a prospective observational study of patients with documented or suspected bacterial pneumonia. SETTING: Data were collected in 74 acute care hospitals across the US. PATIENTS: This evaluation was based on a consecutive sample of 1822 adult patients (> 18 years of age) with documented or suspected bacterial pneumonia who were being treated with a cephalosporin, a penicillin, or an aminoglycoside over a 3-month period. Patients were followed for the duration of antibiotic therapy and were excluded if antibiotic therapy was < 3 days or if the pneumonia was judged to be nonbacterial. INTERVENTIONS: Clinical pharmacists documented patient demographics, concurrent illnesses and medications, antibiotic administration, relevant laboratory data, and the occurrence of nephrotoxicity and neutropenia. MAIN OUTCOME MEASURES: Validity of investigators' identification of neutropenia and nephrotoxicity as compared with objective laboratory data was assessed by using sensitivity, specificity, and positive and negative predictive value measures. RESULTS: Among the 1502 patients with sufficient data to evaluate neutropenia, there was agreement in 1270 patients (84.6%); likewise, among 1291 patients with sufficient data to evaluate nephrotoxicity there was agreement in 1186 patients (91.9%). Sensitivity of the researchers' assessments was 50.9% and 71.0% for neutropenia and nephrotoxicity, respectively. The negative predictive value was > 95% for both events. CONCLUSIONS: Overall, this evaluation demonstrated that the Drug Surveillance Network can successfully identify targeted adverse events. Moreover, this study highlights the importance of validation for all types of outcomes-oriented research studies.