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Validation of ICD-9-CM codes for major genitourinary birth defects in Military Health System administrative data,
Celeste J Romano1,2, Sandra M Magallon1,2, Clinton Hall1,2
1Deployment Health Research Department, Naval Health Research Center, San Diego, California, USA.
Insights
The accuracy of genitourinary birth defect codes in military health data varies. Refining criteria, like excluding congenital hydronephrosis, improves accuracy for research and surveillance.
Area of Science:
- Medical Informatics
- Pediatric Health
- Public Health Surveillance
Background:
- The Department of Defense Birth and Infant Health Research program focuses on birth defects in military families.
- Assessing the validity of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for genitourinary birth defects is crucial for accurate surveillance.
- Methods for calculating positive predictive value (PPV), negative predictive value (NPV), sensitivity, and specificity were refined.
Purpose of the Study:
- To evaluate the accuracy of ICD-9-CM codes for specific genitourinary birth defects within the Military Health System (MHS).
- To refine methods for calculating diagnostic accuracy measures for birth defect surveillance.
- To improve the reliability of administrative data for research on birth defects in military populations.
Main Methods:
- A stratified random sampling design was used to select cases for chart review among military infants born between 2006 and 2014.
- Positive Predictive Value (PPV), Negative Predictive Value (NPV), sensitivity, and specificity were calculated for individual defects and overall.
- Measures were weighted by the inverse probability of sampling to account for the design.
Main Results:
- Bladder exstrophy codes demonstrated high accuracy (PPV >90%).
- Moderate accuracy was observed for renal dysplasia, renal agenesis/hypoplasia, and hypospadias (PPVs 66%-68%).
- Congenital hydronephrosis codes had low accuracy (PPV 20%), while specificity and NPVs consistently exceeded 98% for all defects. The overall PPV was 50%, improving to 85% after excluding congenital hydronephrosis and requiring multiple diagnostic codes.
Conclusions:
- The validity of ICD-9-CM codes for genitourinary birth defects in MHS data is variable.
- Excluding congenital hydronephrosis and requiring at least two diagnostic codes significantly enhanced the overall PPV.
- Calculating PPV, NPV, sensitivity, and specificity is essential for optimizing criteria for birth defect surveillance and research.
Background:
The Department of Defense Birth and Infant Health Research program is dedicated to birth defects research and surveillance among military families. Here, we assess and refine the validity of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for selected genitourinary birth defects in the Military Health System (MHS). We additionally outline methods for the calculation of positive predictive value (PPV) and negative predictive value (NPV), sensitivity, and specificity using a stratified sampling design.
Methods:
Among military infants born from 2006 through 2014, a random sample of ICD-9-CM screen-positive cases (for six genitourinary birth defects) and screen-negative cases were selected for chart review. PPV, NPV, sensitivity, and specificity were calculated for individual defects and any included defect (i.e., overall); measures were weighted by the inverse probability of being sampled.
Results:
Of 461,557 infants, 686 were sampled for chart review. Bladder exstrophy was accurately reported (PPV: >90%), while the accuracy of renal dysplasia, renal agenesis/hypoplasia, and hypospadias was moderate (PPVs: 66%-68%) and congenital hydronephrosis was low (PPV: 20%). Specificity and NPVs always exceeded 98%. The overall PPV was 50%; however, excluding congenital hydronephrosis screen-positive cases and requiring at least two inpatient or outpatient diagnostic codes resulted in a PPV of 85%.
Conclusions:
The validity of major genitourinary birth defect codes varied in MHS administrative data. The accuracy of an overall defect measure improved by omitting congenital hydronephrosis and requiring at least two diagnostic codes. Although PPV is generally useful for research, additional calculation of NPV, sensitivity, and specificity better informs the identification of appropriate selection criteria across surveillance and research settings.
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