Positive predictive value and sensitivity of ICD-9-CM codes for identifying pediatric leukemia
Sheila Weinmann1,2, Melanie C Francisco1, Marilyn L Kwan3
1Center for Health Research, Kaiser Permanente Northwest, Portland, Oregon, USA.
Insights
Using multiple ICD-9-CM diagnosis codes from electronic health records accurately identifies pediatric leukemia cases. Requiring four or more codes maximizes positive predictive value and sensitivity for epidemiologic studies.
Area of Science:
- Pediatric Oncology
- Health Informatics
- Epidemiology
Background:
- Community-based epidemiologic studies require reliable methods for identifying pediatric leukemia.
- Electronic health records (EHRs) offer a potential data source, but validation is needed.
- International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes are used for diagnoses.
Purpose of the Study:
- To validate the use of ICD-9-CM diagnosis codes for identifying pediatric leukemia cases in EHRs.
- To assess the added value of procedure codes for diagnosis and treatment in improving case identification.
- To determine the optimal number of diagnosis codes for accurate case ascertainment.
Main Methods:
- Retrospective validation study using EHR data from six U.S. integrated health plans (1996-2015).
- Subjects included children and adolescents with at least 120 days of enrollment post-first leukemia code or tumor registry diagnosis.
- Gold standard: health system tumor registry and/or medical record review. Calculated positive predictive value (PPV) and sensitivity based on the number of ICD-9-CM codes.
Main Results:
- One or more ICD-9-CM codes yielded 99% sensitivity but only 70% PPV.
- Two or more codes improved PPV to 90% with 96% sensitivity.
- Four or more codes maximized PPV at 95% and maintained 93% sensitivity.
- Adding chemotherapy or bone marrow procedure codes had minimal impact on PPV or sensitivity.
Conclusions:
- Requiring multiple ICD-9-CM diagnosis codes (specifically four or more) from EHRs provides high PPV and sensitivity for identifying pediatric leukemia.
- This validated method can facilitate community-based epidemiologic studies of pediatric leukemia.
- Procedure codes do not significantly enhance the accuracy of case identification when diagnosis codes are used judiciously.
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.
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