Hospital days, hospitalization costs, and inpatient mortality among patients with mucormycosis: a retrospective analysis of US hospital discharge data

Mucormycosis is a rare and potentially fatal fungal infection occurring primarily in severely immunosuppressed patients. Because it is so rare, reports in the literature are mainly limited to case reports or small case series. The aim of this study was to evaluate inpatient mortality, length of stay (LOS), and costs among a matched sample of high-risk patients with and without mucormycosis in a large nationally representative database.

We conducted a retrospective analysis using the 2003–2010 Healthcare Cost and Utilization Project – Nationwide Inpatient Sample (HCUP-NIS). The NIS is a nationally representative 20% sample of hospitalizations from acute care United States (US) hospitals, with survey weights available to compute national estimates. We classified hospitalizations into four mutually exclusive risk categories for mucormycosis: A- severely immunocompromised, B- critically ill, C- mildly/moderately immunocompromised, D- major surgery or pneumonia. Mucormycosis hospitalizations (“cases”) were identified by ICD-9-CM code 117.7. Non-mucormycosis hospitalizations (“non-cases”) were propensity-score matched to cases 3:1. We examined demographics, clinical characteristics, and hospital outcomes (mortality, LOS, costs). Weighted results were reported.

From 319,366,817 total hospitalizations, 5,346 cases were matched to 15,999 non-cases. Cases and non-cases did not differ significantly in age (49.6 vs. 49.7 years), female sex (40.5% vs. 41.0%), White race (53.3% vs. 55.9%) or high-risk group (A-49.1% vs. 49.0%, B-20.0% vs. 21.8%, C-25.5% vs. 23.8%, D-5.5% vs. 5.4%). Cases experienced significantly higher mortality (22.1% vs. 4.4%, P < 0.001), with mean LOS and total costs more than 3-fold higher (24.5 vs. 8.0 days and $90,272 vs. $25,746; both P < 0.001).

In a national hospital database, hospitalizations with mucormycosis had significantly higher inpatient mortality, LOS, and hospital costs than matched hospitalizations without mucormycosis. Findings suggest that interventions to prevent or more effectively treat mucormycosis are needed.