MON-387 - Rising in-Hospital Mortality in Myxedema Coma: An 8-Year National Trend Analysis

Introduction:
Myxedema coma (MC) is a rare, life-threatening endocrine emergency characterized by severe hypothyroidism. Despite increased awareness and improved diagnostic testing, MC continues to have a high mortality rate in hospitalized patients. This study examines trends in in-hospital mortality among patients admitted with MC.

Objective:
To evaluate the 8-year trend in in-hospital mortality among patients with MC using the National Inpatient Sample(NIS).

Methods:
This retrospective cohort study used the NIS from Q4 2015 through 2022. Adult patients admitted with MC were identified using ICD-10 code E03.5. The primary outcome was overall 8-year in-hospital mortality trends, with subgroup analyses by socioeconomic status (SES) and sex. Secondary outcomes included trends in complications, demographics, and comorbidities potentially contributing to mortality. Confounders including demographics, SES, and comorbidities were adjusted using stepwise survey-weighted multivariable logistic regression.

Results:
Among 8,385 hospitalizations for MC from 2015-2022 using the NIS, overall in-hospital mortality was 10.1%. Mortality increased by 12.3% annually (aOR 1.123, 95% CI 1.03-1.22; p-trend=0.006), with unadjusted mortality rising from 4.35% in 2015 to 9.7% in 2022 and peaking at 14.96% in 2020 (p < 0.005). Mean age was 66.9 years with no significant temporal trend (p=0.757). Mortality increased annually among females (13%; p-trend=0.016) and patients of lower SES (16%; p-trend=0.002). Total hospitalization charges increased by $4,603 per year (p=0.005). Vasopressor use increased over time (p-trend < 0.005), while intubation rates declined (p-trend=0.019). Rates of acute kidney injury (AKI) increased over time (p-trend=0.017). No significant temporal trends were observed for race, length of stay, Charlson Comorbidity Index, cardiac arrest, arrhythmias, or acute respiratory distress syndrome.

Conclusion:
In this national analysis, in-hospital mortality among patients admitted with MC increased significantly from 2015-2022, peaking in 2020 with persistently elevated rates thereafter. This rise occurred despite stable age and comorbidity burden, suggesting worsening outcomes are not driven by demographic shifts alone. Increasing vasopressor use and AKI, alongside declining intubation rates, suggest greater illness severity at presentation and potential delays in care. The disproportionate mortality increase among lower SES patients highlights the impact of structural barriers and limited access to outpatient thyroid care. While the COVID-19 pandemic likely amplified these trends, sustained post-pandemic mortality suggests ongoing vulnerability in this population. These findings emphasize the need for earlier identification of high-risk patients and targeted interventions to reduce socioeconomic disparities in this endocrine emergency.

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