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.