Comparing Two Systems for Surveillance of Neonatal Abstinence Syndrome in Alaska

BACKGROUND: A rise in prenatal opioid use has been linked to a national increase in Neonatal Abstinence Syndrome (NAS). State population-based analyses of NAS often rely on the Hospital Discharge Database (HDD), however in Alaska this system has limited representation of the total population prior to 2015 when participation became mandatory, is unavailable for 2013-2014 due to insufficient participation, and cannot be linked to birth certificates to obtain demographic and birth information relevant for public health interventions. Furthermore, billing code information in the HDD is not specific to withdrawal symptoms due to in utero exposure to opiates.

METHODS: We calculated NAS incidence in Alaska using two sources: the HDD for 2001–2012 and Medicaid data for claims made January 1, 2004–November 30, 2015. NAS cases were identified by the ICD-9-CM and ICD-10-CM codes for Drug Withdrawal Syndrome in Newborn (779.5 and P96.1). We evaluated and compared NAS trends from both sources, and evaluated the feasibility and utility of applying additional criteria to exclude possible iatrogenic NAS based on very low birth weight (VLBW) and complex medical conditions.

RESULTS: The population incidence of NAS according to the HDD increased from 0.8 in 2001 to 5.1 per 1,000 births in 2012 (p-value for trend < 0.001). Among the Medicaid population, the incidence increased from 1.6 in 2004 to 6.4 per 1,000 Medicaid-eligible births in 2014 (p-value for trend < 0.001). Incidence was not calculated for 2015 due to a lack of final birth data, however the number of cases through November was higher than in any other prior year. While 53% of Alaska births during 2001–2012 were eligible for Medicaid, 78% of the NAS cases in the HDD indicated that Medicaid was the primary payer.

Proxy information on birth weight was available for 346 of the 372 cases in the HDD (93%). Overall, 14 (4%) met at least one exclusion criteria of VLBW (n=7) or one of five complex medical conditions (n=9).

Among the 227 Medicaid cases, 208 (92%) linked to an Alaska birth certificate.

CONCLUSIONS: In Alaska, utilizing Medicaid is a feasible alternative to the HDD for surveillance of trends in NAS. The Medicaid population represents a majority of NAS cases, data are more timely, and records can be linked to birth certificates which provide information for targeting interventions. Applying extensive exclusion criteria for possible iatrogenic NAS did not change estimates or interpretation of trends by any meaningful amount.