Citation

Leonard CE, Haynes K, Localio AR, Hennessy S, Tjia J, Cohen A, Kimmel SE, Feldman HI, Metlay JP. J. Clin. Epidemiol. 2008; 61(6): 561-571.

Affiliation

Center for Clinical Epidemiology/Biostatistics, Department of Biostatistics/Epidemiology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA; University of Pennsylvania Program for the Reduction in Medication Errors, Philadelphia, PA.

Copyright

(Copyright © 2008, Elsevier Publishing)

DOI

10.1016/j.jclinepi.2007.08.003

PMID

18471660

Abstract

OBJECTIVE: We sought to examine the validity of specific hospital discharge codes in identifying drug toxicity precipitating hospitalization, among elderly users of high-risk medications. STUDY DESIGN AND SETTING: We conducted a cross-sectional evaluation assessing the diagnostic test characteristics of International Classification of Diseases-9 External-Cause-of-Injury codes (E-codes) compared with a reference standard of medical record review. This study was nested within a prospective cohort of elders using warfarin, digoxin, or phenytoin as identified in the Pharmaceutical Assistance Contract for the Elderly benefit program. RESULTS: We identified 4,803 subjects contributing 11,409 person-years of exposure to at least one of three drug groups. Subjects experienced 8,756 hospitalizations, of which 304 were deemed, by expert review, to be a result of an adverse event of warfarin, digoxin, or phenytoin. The sensitivity, specificity, and positive (PPVs) and negative predictive values for drug-specific E-codes were warfarin-25.5%, 98.3%, 46.6%, and 95.7%; digoxin-84.0%, 99.1%, 56.8%, and 99.8%; and phenytoin-86.7%, 98.7%, 59.1%, and 99.7%. CONCLUSIONS: E-codes for digoxin and phenytoin have a high sensitivity, but E-codes for all three medications have poor PPVs, a result that might produce misclassification in studies based solely on discharge coding. Investigators should confirm such rare events via medical record review.

Language: en