Purpose: Current literature on epidemiology of acute disseminated encephalomyelitis (ADEM) and resource utilization is limited. Our aim was to determine the temporal trends in the epidemiology of ADEM and its outcomes in the United States (US) from 2006 through 2014. Methods: We identified pediatric hospitalizations (≤ 18 years) from the National Inpatient Sample (NIS) 2006-2014. To avoid duplication of data from the receiving hospital, we limited all admissions that were transferred out. ADEM hospitalizations were identified using International Classification of Diseases, 9th Revision, and Clinical Modification (ICD9-CM) code 323.61 in any diagnosis field. We examined the trends in the incidence of ADEM with respect to age, gender, race, and census region by dividing the study period into three discrete 3-year epochs (2006-08, 2009-11 and 2012-14). Incidence was expressed as the number of ADEM cases per 100,000 population. We analyzed outcomes of ADEM in terms of mortality, length of stay (LOS) and cost of hospitalization (inflation adjusted). Weights provided by NIS were used to generate national estimates. For trend analysis, we used chi-square test of trend for proportions with Cochran Armitage test via ‘trend’ command in Statistical Analysis Software (SAS®). P-value < 0.05 was considered significant. Results: 54 million pediatric hospitalizations were identified from 2006-2014 of which 3319 were attributable to ADEM hospitalizations. This yielded an overall incidence of 0.5 per 100,000 population. Between 2006-08 and 2012-14, the incidence of ADEM increased from 0.4 to 0.6 per 100,000 (P-trend <0.001). Blacks and Hispanics experienced a significant increase in ADEM incidence during the study period 90.2 to 0.5 per 100,000 population). ADEM incidence declined in the Northeast while it increased in the remaining three census regions. There was no sex preponderance and 67% of ADEM hospitalizations were <9 years old. Most common diagnostic modalities utilized were lumbar puncture (LP) [64%] and brain MRI (28%) Intravenous Immunoglobulin (IVIG) infusion and steroids were the common therapeutic modalities Mortality remained stable inform 2006-08 to 2012-14 (1.1 to 1.5%; P-trend 0.07). Median length of Stay remained stable from 2006-08 to 2012-14 (4.8 to 5.5 days; P-trend = 0.3). However, median inflation adjusted cost increased from $11,594 in 2006-08 to$16,193 in 2012-14 (P-trend 0.002). Conclusion: In this large nationwide cohort of ADEM hospitalizations, the incidence of ADEM increased during the study period. LP and IVIG remains common diagnostic and treatment modalities. Mortality and LOS have remained stable over time but inflation adjusted cost of hospitalizations has increased.

Figure 1