Diagnosis Codes and Case Definitions for Neonatal Abstinence Syndrome.

BACKGROUND AND OBJECTIVES: The increase in neonatal abstinence syndrome (NAS) has underscored the need for NAS surveillance programs, but many rely on passive surveillance using unverified diagnosis codes. Few studies have evaluated the validity of these codes, and no study has assessed the recently proposed Council of State and Territorial Epidemiologists (CSTE) case definition. The Florida Birth Defects Registry investigated the accuracy of International Classification of Diseases, 10th Revision, Clinical Modification codes related to NAS (P96.1 and P04.49) and assessed the sensitivity of the CSTE case definition. METHODS: We identified a sample of infants born during 2016 coded with P96.1 and/or P04.49. Record review was completed for 128 cases coded with P96.1, 68 with P04.49, and 7 with both codes. Lacking consensus regarding a gold standard definition of NAS, we used clinical data to classify each case using the Florida and CSTE definitions. The code-specific accuracy was measured by using the positive predictive value (PPV). The clinical characteristics indicative of NAS were compared for case classification based on both definitions. RESULTS: By using the Florida definition, the overall PPV was 68% but varied by code: 95.3% for P96.1 and 13.2% for P04.49. The overall (47.8%) and code-specific PPVs were lower by using the CSTE definition. Comparison of clinical characteristics demonstrated that 60.7% of cases classified as no NAS by using the CSTE definition had robust clinical signs of NAS. In our sample, the CSTE case definition underestimated NAS prevalence. CONCLUSIONS: Only the P96.1 International Classification of Diseases, 10th Revision, Clinical Modification code displayed high accuracy. Discordance in NAS case definitions and surveillance methodologies may result in erroneous comparisons and conclusions that negatively impact NAS-related surveillance and research.

A New Scoring System for the Assessment of Neonatal Abstinence Syndrome.

OBJECTIVE: This study aimed to evaluate the concordance of a new scoring system for neonatal abstinence syndrome (NAS) and NAS scores to the traditional Modified Finnegan Neonatal Abstinence Scoring Tool (M-FNAST) score. The NAS score is based on the physiology of withdrawal, with equal emphasis on behavior, and neurological signs. STUDY DESIGN: The NAS scores for a control group of 202 healthy, term neonates were compared with those for 45 term neonates with NAS. The NAS and M-FNAST scores obtained simultaneously in 45 term neonates with NAS were compared using correlation, linear regression, and receiver operating characteristic curve analysis to determine the validity, reliability, and specificity of the NAS scores. RESULTS: The association between the NAS and M-FNAST scores was high (Spearman's correlation, 83%; linear regression, 83%), with an area under the curve of the NAS score of 1.00 (p < 0.01). A cut-off NAS score ≥4 identified NAS neonates with a sensitivity of 100% and specificity of 96%. The values of intraclass correlation, interrater agreement, and Cronbach's α were 0.63, 0.88, and 0.63, respectively. CONCLUSION: The new NAS scoring system is valid, reliable, physiologically based, and correlates closely with the M-FNAST score. The NAS scores may require further validation before its use in clinical practice.

Assessing the Burden of Neonatal Abstinence Syndrome: Validation of ICD-9-CM Data, Florida, 2010-2011.

CONTEXT: On October 1, 2015, the United States transitioned from using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) to ICD-10-CM. Continuing to monitor the burden of neonatal abstinence syndrome (NAS) after the transition presently requires use of data dependent on ICD-9-CM coding to enable trend analyses. Little has been published on the validation of using ICD-9-CM codes to identify NAS cases. OBJECTIVE: To assess the validity of hospital discharge data (HDD) from selected Florida hospitals for passive NAS surveillance, based on ICD-9-CM codes, which are used to quantify baseline prevalence of NAS. DESIGN: We reviewed infant and maternal data for all births at 3 Florida hospitals from 2010 to 2011. Potential NAS cases included infants with ICD-9-CM discharge codes 779.5 and/or 760.72 in linked administrative data (ie, HDD linked to vital records) or in unlinked HDD and infants identified through review of neonatal intensive care unit admission logs or inpatient pharmacy records. Confirmed infant cases met 3 clinician-proposed criteria. Sensitivity and positive predictive value were calculated to assess validity for the 2 ICD-9-CM codes, individually and combined. RESULTS: Of 157 confirmed cases, 134 with 779.5 and/or 760.72 codes were captured in linked HDD (sensitivity = 85.4%) and 151 in unlinked HDD (sensitivity = 96.2%). Positive predictive value was 74.9% for linked HDD and 75.5% for unlinked HDD. For either HDD types, the single 779.5 code had the highest positive predictive value (86%), lowest number of false positives, and good to excellent sensitivity. CONCLUSIONS: Passive surveillance using ICD-9-CM code 779.5 in either linked or unlinked HDD identified NAS cases with reasonable validity. Our work supports the use of ICD-9-CM code 779.5 to assess the baseline prevalence of NAS through 2015.