Incidence and risk factors for mucormycosis in renal transplant patients

BACKGROUND: Renal transplant patients are at increased risk for mucormycosis. Diabetes, neutropenia, deferoxamine therapy, and immunosuppressive medications have been associated with increased risk of mucormycosis in studies of solid organ transplant recipients. To focus on renal transplant patients, the US Renal Data System (USRDS) was queried to determine the incidence and risk factors for mucormycosis.

METHODS: All renal transplant patients in the USRDS from 1988 to 2015 were queried for a diagnosis of mucormycosis after the first transplant date using ICD-9 and ICD-10 codes. The International Classification of Diseases (ICD) codes, which currently exist in the ninth and tenth revisions, are a global system of classification used to code diagnoses, procedures, and symptoms. We defined proven mucormycosis by a histopathologic or fungal stain procedure code within 7 days of the diagnosis code. Logistic regression controlling for person-years at risk was used to examine demographic and clinical diagnosis risk factors for mucormycosis.

RESULTS: Of the 306,482 renal transplant patients, 222 (0.07%) had codes consistent with proven mucormycosis. The incidence of mucormycosis increased from 1990 to 2000 (peak 17.6 per 100,000 person-years) and subsequently demonstrated more variability. Hispanic ethnicity (OR=1.45), age 65 years or greater (OR=1.64), other or black race compared with white race (OR=1.96 and 1.74), cadaver or other donor type (OR=2.41), and receiving tacrolimus (OR=2.09) were associated with increased risk. Comorbidities associated with decreased risk of mucormycosis included female sex (OR=0.68), iron overload (OR=0.56), and receiving mycophenolate mofetil (OR=0.67) or azathioprine (OR=0.53).

CONCLUSIONS: In renal transplant patients, age, deceased donor graft transplant, tacrolimus administration, race other than white, and Hispanic ethnicity were associated with increased risk of mucormycosis. Unexpectedly, iron overload was protective. Mucormycosis is a rare infection in renal transplant patients which should be considered in patients with the above risk factors after more common infections have been ruled out.