Longitudinal Epidemiology of Mucormycosis Within the Veterans Health Administration: A Retrospective Cohort Study Over a 20-Year Period.

Background: Mucormycosis is a rare but critical infection. Due to its rarity, there is scarce evidence about the longitudinal changes in the epidemiology of mucormycosis in the US.

Objectives: We investigated the longitudinal epidemiology, detailed clinical characteristics, treatment and outcomes of patients with mucormycosis within the US Veterans Health Administration (VHA) over 20-year period.

Patients/methods: All adult patients who were admitted to an acute-care hospital with a diagnosis of mucormycosis within the VHA from January 2003 to December 2022.

Results: Our study included 201 patients from 68 hospitals. Incidence rates of mucormycosis increased from 1.9 per 100,000 hospitalisations in 2003 to 3.3 per 100,000 hospitalisations in 2022, with a peak incidence at 5.9 per 100,000 hospitalisations in 2021, when the Delta wave of COVID-19 hit the US. Rhino-orbital (37.3%) and pulmonary mucormycosis (36.8%) were the most common types of infection. Diabetes mellitus (59.1%) and leukaemia (28.9%) were most common comorbidities predisposing to mucormycosis. Use of posaconazole or isavuconazole increased over time. The 90-day and 1-year mortalities were 35.3% and 49.8%, respectively. The mortality was lower in more recent years (2013-2017, 2018-2022) compared to earlier years (2003-2007). Age ≥65 (adjusted odds ratio [aOR]: 3.47, 95% CI 1.59-7.40), leukaemia as a comorbidity (aOR: 2.66, 95% CI 1.22-5.89) and central nervous system infection (aOR: 10.59, 95% CI 2.81-44.57) were significantly associated with higher 90-day mortality.

Conclusions: Our longitudinal cohort study suggests the increasing incidence rates but lower mortality of mucormycosis over this 20-year period.