Neonatal abstinence syndrome (NAS) is a postnatal drug withdrawal syndrome primarily
caused by maternal opiate use. No national estimates are available for the incidence
of maternal opiate use at the time of delivery or NAS.
To determine the national incidence of NAS and antepartum maternal opiate use and
to characterize trends in national health care expenditures associated with NAS between
2000 and 2009.
A retrospective, serial, cross-sectional analysis of a nationally representative sample
of newborns with NAS. The Kids' Inpatient Database (KID) was used to identify newborns
with NAS by International Classification of Diseases, Ninth Revision, Clinical Modification
(ICD-9-CM) code. The Nationwide Inpatient Sample (NIS) was used to identify mothers
using diagnosis related groups for vaginal and cesarean deliveries. Clinical conditions
were identified using ICD-9-CM diagnosis codes. NAS and maternal opiate use were described
as an annual frequency per 1000 hospital births. Missing hospital charges (<5% of
cases) were estimated using multiple imputation. Trends in health care utilization
outcomes over time were evaluated using variance-weighted regression. All hospital
charges were adjusted for inflation to 2009 US dollars.
Incidence of NAS and maternal opiate use, and related hospital charges.
The separate years (2000, 2003, 2006, and 2009) of national discharge data included
2920 to 9674 unweighted discharges with NAS and 987 to 4563 unweighted discharges
for mothers diagnosed with antepartum opiate use, within data sets including 784,191
to 1.1 million discharges for children (KID) and 816,554 to 879,910 discharges for
all ages of delivering mothers (NIS). Between 2000 and 2009, the incidence of NAS
among newborns increased from 1.20 (95% CI, 1.04-1.37) to 3.39 (95% CI, 3.12-3.67)
per 1000 hospital births per year (P for trend < .001). Antepartum maternal opiate
use also increased from 1.19 (95% CI, 1.01-1.35) to 5.63 (95% CI, 4.40-6.71) per 1000
hospital births per year (P for trend < .001). In 2009, newborns with NAS were more
likely than all other hospital births to have low birthweight (19.1%; SE, 0.5%; vs
7.0%; SE, 0.2%), have respiratory complications (30.9%; SE, 0.7%; vs 8.9%; SE, 0.1%),
and be covered by Medicaid (78.1%; SE, 0.8%; vs 45.5%; SE, 0.7%; all P < .001). Mean
hospital charges for discharges with NAS increased from $39,400 (95% CI, $33,400-$45,400)
in 2000 to $53,400 (95% CI, $49,000-$57,700) in 2009 (P for trend < .001). By 2009,
77.6% of charges for NAS were attributed to state Medicaid programs.
Between 2000 and 2009, a substantial increase in the incidence of NAS and maternal
opiate use in the United States was observed, as well as hospital charges related