Histoplasmosis-Related Healthcare Use, Diagnosis, and Treatment in the US

Histoplasmosis is associated with a wide spectrum of illness and a substantial burden for some patients, according to data from health insurance claims in the United States published in Clinical Infectious Diseases.

To characterize testing and treatment practices as well as burden of this acute pulmonary or disseminated disease, which ranges from asymptomatic to life threatening, the study investigators used the IBM® MarketScan® Research Databases to identify patients with histoplasmosis. The research team analyzed claims in the 3 months before to 1 year after diagnosis and examined differences between those with probable (hospitalized or >1 outpatient visit) and suspect (1 outpatient visit) disease.

The data showed that 54% of 1935 patients (943 probable cases, 922 suspected cases) had codes for symptoms or findings consistent with histoplasmosis. A further 35% had ≥2 healthcare visits in the 3 months before diagnosis. In total, 646 patients had fungal-specific laboratory test: 349 with a histoplasmosis antibody test (18%), 349 with a Histoplasma antigen test (18%), 249 patients with a fungal smear (15%) or 223 with fungal culture (12%), and 464 (24%) had a biopsy. Antifungal medications were prescribed in the outpatient setting to 49% of those with probable disease and 10% of those with suspected disease. A total of 19% of patients were hospitalized and patient’s last histoplasmosis-associated healthcare visits occurred a median of 6 months after diagnosis.

Twenty-nine percent of patients received outpatient antifungal therapy — 49% of whom were categorized as having probable disease, and 10% who had suspected disease. The mean time from diagnosis to prescription of antifungal medication was 38 days. Patients with immunocompromise were more likely to receive antifungal medications for longer durations compared with those who did not have immunocompromise.

One limitation to the study was the lack of detail available for the classification of different forms of histoplasmosis. Despite attempts made by researchers to capture incident and more acute infections, they acknowledged estimates could be falsely high if diagnoses were recorded at visits after patients’ illnesses resolved. Low overall histoplasmosis-specific testing rates were found, but it was not possible to explore the hypothesis that some patients could have had Histoplasma detected on a nonfungal culture because MarketScan data do not include laboratory test results.  

Several other limitations were noted, including possible underestimations of the numbers of patients receiving antifungal medications, possible inherent flaws in administration data, and that the healthcare experiences of patients in this convenience sample of the commercially insured population may differ from those of people with other insurance types or the uninsured.

According to the study investigators, this study offers insight into histoplasmosis-related healthcare use, testing, and treatment among privately insured patients. Specifically, researchers highlighted that their results “underscore the importance of considering [acute pulmonary histoplasmosis] in patients with lower respiratory symptoms, as well as those with lung nodules or chest lymphadenopathy, especially when no other etiology is found.” In addition, because more than one-third of patients resided outside of areas often associated with histoplasmosis, there is a need for greater awareness of this disease among both healthcare providers and the public.

The study authors recommended that, “more detailed data on the effects of histoplasmosis on patients and testing and treatment practices, will help to guide awareness efforts and inform early intervention strategies.”

Reference

Benedict K, Beer KD, Jackson BR. Histoplasmosis-related healthcare use, diagnosis, and treatment in a commercially insured population, United States [published online April 30, 2019]. Clin Infect Dis. doi:10.1093/cid/ciz324