Inpatient morbidity and mortality of measles in the United States

Background Measles is an extremely contagious, vaccine-preventable infection that was officially declared eradicated in the US in 2000. However, measles outbreaks are increasingly occurring in the US. Measles cases have considerable morbidity requiring hospitalization, yet little is known about hospitalization and complications from measles in recent years. Objectives To analyze the frequency, predictors, costs and other outcomes of hospitalization for measles in the US. Methods The 2002-2016 Nationwide Inpatient Sample, containing a 20% sample of US hospitalizations (n = 96,568,625), was analyzed. Measles and comorbidities were defined by International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) or ICD-10-CM codes. Multivariable survey logistic regression and linear regression models controlling for sociodemographic demographic factors were constructed to understand associations with organ-specific complications, and cost of care and length of stay, respectively. Results Overall, 1,018 measles hospitalizations occurred in 2002-2016, and hospitalizations increased over time. In multivariable logistic regression models, measles was associated with higher odds of gastrointestinal, hematologic, infectious, neurologic, ophthalmologic, pulmonary, and renal complications, with the strongest association observed with encephalitis (39.84 [16.51-96.12], P < 0.0001). Increased length of stay (LOS) and similar cost of care (mean [95% CI]; 4.8 [4.4-5.4]; $7,438 [$6,446-$8,582]) were observed versus (vs.) all other admissions (4.5 [4.4-4.5]; P < 0.01; $7,854 [$7,774-$7,935], P > 0.05). There were 34 deaths in hospitalized measles patients; inpatient mortality was numerically higher in those with vs. without measles (proportion +/- SEM: 3.3 +/- 1.2% vs. 2.3 +/- 0.01%, P = 0.333). Limitations Lack of outpatient or prescription data. Conclusions Measles continues to pose a substantial and preventable health care burden, with serious complications, hospitalization and inpatient mortality. Further studies are needed to improve the prevention and management of measles.