Positive predictive value and sensitivity of ICD-9-CM codes for identifying pediatric leukemia.

ABSTRACT

BACKGROUND: To facilitate community-based epidemiologic studies of pediatric leukemia, we validated use of ICD-9-CM diagnosis codes to identify pediatric leukemia cases in electronic medical records of six U.S. integrated health plans from 1996-2015 and evaluated the additional contributions of procedure codes for diagnosis/treatment. PROCEDURES Subjects (N = 408) were children and adolescents born in the health systems and enrolled for at least 120 days after the date of the first leukemia ICD-9-CM code or tumor registry diagnosis. The gold standard was the health system tumor registry and/or medical record review. We calculated positive predictive value (PPV) and sensitivity by number of ICD-9-CM codes received in the 120-day period following and including the first code. We evaluated whether adding chemotherapy and/or bone marrow biopsy/aspiration procedure codes improved PPV and/or sensitivity. RESULTS: Requiring receipt of one or more codes resulted in 99% sensitivity (95% confidence interval [CI] 98-100%) but poor PPV (70%; 95% CI 66-75%). Receipt of two or more codes improved PPV to 90% (95% CI 86-93%) with 96% sensitivity (95% CI 93-98%). Requiring at least four codes maximized PPV (95%; 95% CI 92-98%) without sacrificing sensitivity (93%; 95% CI 89-95%). Across health plans, PPV for four codes ranged from 84-100% and sensitivity ranged from 83-95%. Including at least one code for a bone marrow procedure or chemotherapy treatment had minimal impact on PPV or sensitivity. CONCLUSIONS: The use of diagnosis codes from the electronic health record has high PPV and sensitivity for identifying leukemia in children and adolescents if more than one code is required.