Voriconazole Versus Itraconazole for the Initial and Step-down Treatment of Histoplasmosis: A Retrospective Cohort

Background: Itraconazole is the preferred azole for histoplasmosis in the current Infectious Diseases Society of America guidelines. Voriconazole is increasingly used as treatment for histoplasmosis; it has in vitro activity against Histoplasma capsulatum and has shown success in case reports and small case series, but may have a lower barrier to resistance. No comparative studies have been published. Methods: We constructed a single-center, retrospective cohort of adult patients diagnosed with histoplasmosis from 2002 to 2017. Individual charts were reviewed to gather clinical information, including demographics, clinical features, immune status, treatments, and mortality. Patients were categorized based on the choice of azole and use as an initial treatment or as a step-down therapy from amphotericin B. Initial therapies with other azoles were excluded. Mortality was compared using a multivariable Cox proportional hazards with Heaviside function at 42 days. Results: We identified 261 cases of histoplasmosis from 2002 to 2017. After excluding patients not treated with itraconazole or voriconazole, 194 patients remained. Of these, 175 (90%) patients received itraconazole and 19 (10%) received voriconazole. There were no significant demographic differences between patient populations receiving either azole as their initial azole treatment. Death at 180 days occurred in 41 patients (23.4%) in the itraconazole group and 6 patients (31.6%) in the voriconazole group. Patients on voriconazole had a statistically significant increase in mortality during the first 42 days after initiation of treatment when compared to patients receiving itraconazole (hazard ratio, 4.30; 95% confidence interval, 1.3-13.9; P =. 015), when controlled for other risk factors. Conclusions: Voriconazole in histoplasmosis was associated with increased mortality in the first 42 days when compared to itraconazole.