Validity of Hospital Discharge Data for Identifying Infants with Cardiac Defects

Objective: To examine validity of the International Classification of Diseases, 9th Edition, Clinical Modification (ICD-9-CM) codes in discharge data for identifying infants with cardiac defects according to surveillance guidelines.

Study Design: Retrospective medical record review of infants born in 2001 at one hospital in Minneapolis, Minnesota. Infants were identified using ICD-9-CM codes from hospital discharge data, and keywords in medical records.

Results: Of 2,697 children, ICD-9-CM codes identified 66 infants coded with cardiac defects; physician review confirmed 24 had cardiac defects. Only 35 of 85 (41.2%) ICD-9-CM codes accurately reflected the cardiac defect diagnoses. Additional case finding located four infants with five cardiac defects. Sensitivity of ICD-9-CM codes for identifying these infants was 0.857, predictive value positive was 0.364.

Conclusions: ICD-9-CM codes from hospital discharge data identified most infants with cardiac defects, but many were false positives. ICD-9-CM codes were inaccurate for specific cardiac defects.