Histoplasmosis-related Healthcare Use, Diagnosis, and Treatment in a Commercially Insured Population, United States

Abstract

Background: Infections with Histoplasma can range from asymptomatic to life-threatening acute pulmonary or disseminated disease. Histoplasmosis can be challenging to diagnose and is widely underrecognized. We analyzed insurance claims data to better characterize histoplasmosis testing and treatment practices and its burden on patients.

Methods: We used the IBM MarketScan Research Databases to identify patients with histoplasmosis (International Classification of Diseases, Ninth Revision, Clinical Modification codes 115.00-115.99) during 2012-2014. We analyzed claims in the 3 months before to the 1 year after diagnosis and examined differences between patients with probable (hospitalized or >1 outpatient visit) and suspected (1 outpatient visit) histoplasmosis.

Results: Among 1935 patients (943 probable, 992 suspected), 54% had codes for symptoms or findings consistent with histoplasmosis and 35% had ≥2 healthcare visits in the 3 months before diagnosis. Overall, 646 (33%) had any fungal-specific laboratory test: histoplasmosis antibody test (n = 349 [18%]), Histoplasma antigen test (n = 349 [18%]), fungal smear (n = 294 [15%]), or fungal culture (n = 223 [12%]); 464 (24%) had a biopsy. Forty-nine percent of probable patients and 10% of suspected patients were prescribed antifungal medication in the outpatient setting. In total, 19% were hospitalized. Patients' last histoplasmosis-associated healthcare visits occurred a median of 6 months after diagnosis.

Conclusions: Some histoplasmosis patients experienced severe disease, apparent diagnostic delays, and prolonged illness, whereas other patients lacked symptoms and were likely diagnosed incidentally (eg, via biopsy). Low rates of histoplasmosis-specific testing also suggest incidental diagnoses and low provider suspicion, highlighting the need for improved awareness about this disease.

Keywords: antifungal treatment; diagnosis; histoplasmosis; hospitalization; outpatients.

Figure 1:. Days between index date and selected diagnoses and diagnostic tests (A) and prescription medications (B), suspect vs. probable histoplasmosis patients, 2012–2014

Histogram bars indicate the number of events on a given day before or after a patient’s initial histoplasmosis diagnosis, or index date. Index dates are denoted by gray vertical lines. For readability, visits and prescriptions that occurred 181–365 days after index are not shown. These represent 2–25% of visits and 26–38% of prescriptions. Codes for pneumonia, unspecified lung disease, and diagnostic tests increased in the days leading up to the index date and declined sharply thereafter. Antibiotics were more commonly prescribed before the index date than after, whereas antifungals were prescribed much more commonly after the index date. Rates of corticosteroid prescriptions were generally similar before and after histoplasmosis diagnosis, with a minor peak on the index date.

Figure 2:. Histoplasmosis antibody or antigen testing, fungal culture or smear, and biopsy, histoplasmosis patients, 2012–2014

Figure represents 890 unique patients with at least one of the following diagnostic tests: fungal culture/smear, biopsy, or antibody or antigen test.