Geographic distribution and associated mortality of invasive aspergillosis and mucormycosis among Medicare enrollees in the United States (2008-2015)

Background: 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. Methods: 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. Findings: 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) Interpretation: 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.