Background/Purpose: Adult-onset Still’s Disease is a rare systemic autoinflammatory disorder characterized by spiking fever, arthralgia/arthritis, skin rash, and elevated inflammatory markers (ferritin). Estimated incidence ranges from 0.16 to 0.4 cases per 100,000 persons and is associated with significant morbidity during systemic flares requiring inpatient management. There is a lack of research related to hospitalization trends and outcomes of patients with this disease within the United States. Hence, we conducted this analysis from national databases to investigate the hospitalization trends of Adult Onset Still’s Disease pre and post COVID-19 pandemic era.

Methods: We used the National Inpatient Sample (NIS), a database that includes a subset of hospital discharges in 50 states, to identify patients with adult-onset Still’s disease who were admitted to the hospital due to any cause. Patients who were admitted in the years 2016 to 2022 (including the COVID-19 pandemic) were enrolled in the study. Adult-onset Still’s disease was defined based on the ICD-10 code M06.1. Patients were excluded based on age cut-off of < 15 years, and as well as juvenile rheumatoid arthritis identified as M08.2 were not included in the analysis. Discharge weights were applied to estimate national level representation. Adjusted hospital costs were reported for inflation in the year 2022 according to the U.S. Department of Labor inflation index for Medical Care Consumer Price Index (CPI) for cost-based analysis. Cochrane-armitage and Jonckheere-Terpstra test were applied as indicated to analyze the trends over the study period for in-hospital mortality rates, length of stay, inflation adjusted hospitalization costs respectively.

Results: There were a total of 1827 unweighted and 9135 weighted hospital discharges reported with a history of adult onset’s still disease on payer information through healthcare cost and utilization project (HCUP). Among these admissions over a span of 7 years within NIS databases, 40% were males and 60% females, 58% were white by ethnicity. In-hospital mortality rate was 2.3%, and the trend shows an increase amongst non-White population, especially after the COVID-19 pandemic (P=0.006). The most common primary reason of admission remains sepsis following adult-onset Still’s disease complications. Hospitalization costs and length of stay were found higher with male gender (p=0.001 & 0.006 respectively), and non-White population (p=0.001 & 0.005 respectively). Among non-White population, length of stay and hospitalization costs were found highest in Asians/Pacific Islanders population. Also, the mean age of these patients were comparatively higher than other races (50 vs 42 years), as opposed to White population with a mean age of 52 years (p< 0.001).

Conclusion: Sepsis was the most common primary reason for admission. Overall in-hospital mortality was low (2.3%) but increased significantly among non-White populations. Male gender and non-White race were associated with higher hospitalization costs and lengths of stay. Among subgroups, Asian/Pacific Islander patients had the highest resource use and were older at admission than other non-White groups.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/trends-in-hospitalization-and-outcomes-among-patients-admitted-with-adult-onset-stills-disease-in-the-united-states-insights-from-the-national-inpatient-sample-2016-2022/