Factors associated with the incidence and severity of neonatal abstinence syndrome in infants born to opioid dependent mothers

Abstract

Neonatal abstinence syndrome (NAS), the constellation of withdrawal symptoms experienced by neonates exposed to opioids prenatally, is an epidemic affecting an estimated 23,580 infants each year with an annual cost of $720 million. The purpose of this study was to examine factors associated with the incidence and severity of NAS as measured by the need for initiation of neonatal medication, peak medication dose, hospital length of stay (LOS), and hospital costs among newborns born to opioiddependent mothers. A retrospective review of medical records was conducted with two convenience samples: 204 infants born to mothers who used opioids during pregnancy; and 121 of these infants who required treatment with morphine to control symptoms of NAS. Data from April 2011 to September 2017 were collected from medical records of a large Midwestern hospital. Exploratory analysis and descriptive statistics were performed. Associations between independent variables and outcomes were examined using correlations, chi-square, t-tests, analyses of variance, and linear regression. Of the 204 neonates who were exposed to opioids prenatally, 121 (59%) developed symptoms of NAS requiring treatment with morphine. Neonates requiring morphine had significantly higher gestational ages than those who did not (37.7 vs 36.4 weeks; p = < .001) and their mothers were present at the neonates’ bedside a lower proportion of their total hospital stay (mean = 0.5684 of days vs 0.7384 of days; p = < .001). Compared to maternal use of buprenorphine, maternal methadone use was associated with higher peak morphine doses needed to control the neonate’s withdrawal symptoms (0.089 mg/kg versus 0.054 mg/kg; p = .023), and with longer hospital length of stay when compared to maternal use of buprenorphine and other opioid analgesics (34.2 vs. 20.8 vs. 22.5 days, respectively; p=0.02). Higher visitation time from the primary caregiver was correlated with lower hospital LOS (r = -0.421; p = < .001). Future research is needed to examine these relationships prospectively in a larger and more diverse sample. An effective response to the epidemics of opioid use during pregnancy and the incidence of NAS requires ongoing coordinated research and intervention in clinical care, public health, and health policy.