Meconium aspiration syndrome: Incidence and outcomes using discharge data

Background: Meconium aspiration syndrome (MAS) is a leading cause of morbidity and mortality among term, otherwise healthy newborns, yet population studies are rare. Definitions, outcomes and International Classification of Diseases (ICD) codes are heterogenous, complicating estimates of incidence, outcomes and risks. Aims: To measure population incidence, risks and outcomes of MAS by ICD codes. Study design: Retrospective population study. Subjects: Kids Inpatient Database (KID) 2012, a nationally representative weighted sample of newborn discharges in the United States. Outcome measures: Incidence, demographic distribution, and comorbidity associated with MAS. Results: In 2012 there were 9295 weighted discharges diagnosed MAS with symptoms (2.49/1000) and 4304 cases without symptoms (1.15/1000). Newborns with symptoms had nearly twice the length of stay (LOS) (6.68 vs 3.65 days, p 0.001) and nearly 3 times the total charges ($44,473 versus $15,461, p < 0.001) as those without symptoms. Incidence of death was over four times higher (7.7/1000 vs 1.7/1000, p < 0.001), persistent pulmonary hypertension 3 times higher (57.6/1000 vs 15.8/1000, p < 0.001), and hypoxic ischemic encephalopathy 5 times higher (6.2/1000 vs 1.2/1000, p < 0.001) among MAS cases with respiratory symptoms than MAS cases without respiratory symptoms. Odds ratio of MAS with symptoms was 1.54 (95% CI 1.39-1.73) for black newborns compared to whites. Conclusions: Discharge data are useful for providing population estimates of MAS incidence. Prior studies have used consolidated ICD codes for MAS (with and without respiratory symptoms), yet these represent very different disease severities. Combining MAS diagnoses with and without respiratory symptoms misrepresents incidence and disease severity, complicating comparisons of outcomes and prevention strategies.