Invasive mold infections—invasive aspergillosis and mucormycosis—have mortality rates as high as 90% in certain patient populations. Some clinical factors, such as prolonged neutropenia, are well-studied and are closely associated with increased mortality. However, the incidence of invasive aspergillosis and mucormycosis across geographic locations and its impact on mortality remains understudied.

Geographic distribution and incidence rates of invasive aspergillosis and mucormycosis were mapped using 2008–2015 Medicare fee-for-service data. The association between the incidence of these fungal infections and 90-day mortality was investigated using adjusted generalized additive modeling.

53,321 patients were diagnosed with invasive aspergillosis, and 2655 had a diagnosis of mucormycosis. The western region of the United States reported the highest incidence rates (aspergillosis: 25.69 cases per 100,000 person-years; mucormycosis: 1.34 cases per 100,000 person-years). For every increase of 5 cases per 100,000 person-years in the incidence of IA, there was a 3.4% reduction in 90-day mortality (RR: 0.966; 95% CI: 0.961–0.972; p<0.0001)

Invasive aspergillosis and mucormycosis are widely distributed in the United States, with certain regions experiencing significantly higher incidences. For invasive aspergillosis, each increase of 5 cases per 100,000 claimant years was associated with a modest yet statistically significant 3.4% reduction in 90-day mortality. Conversely, the rise in incidence did not significantly affect mortality rates for mucormycosis.