Explaining the “Unexpectedly High” Frequency of Invasive Fungal Disease in a Cohort Study of Solid Organ Transplant Recipients Treated With Belatacept

We took great interest in Bell et al.'s retrospective cohort study of invasive fungal disease (IFD) in solid organ transplant (SOT) recipients treated with belatacept [1].The authors conclude that IFD incidence was "unexpectedly high": 33 of 215 (15%) of SOT recipients and 23 of 56 (41%) of lung recipients developed at least one IFD.While belatacept and concomitant immunosuppression may plausibly increase IFD risk, we are concerned that lack of standardized IFD definitions in this study overestimates IFD frequency and confounds comparisons to other cohorts in the literature.Because fungi often colonize non-sterile sites and clinical and radiographic findings of IFD can be non-specific, it is important to employ standardized definitions when studying IFD.