The incidence, duration, and risk factors for diagnostic delays associated with blastomycosis

Blastomycosis is a rare, fungal infection often with symptoms resembling bacterial or viral pneumonia, and sometimes lung cancer. Delay in diagnosing blastomycosis is associated with worse clinical outcomes, but factors contributing to diagnostic delays remain poorly understood. This study aims to estimate the incidence and duration of diagnostic delays for blastomycosis and identify risk factors associated with missed diagnostic opportunities. We conducted a retrospective cohort study using longitudinal insurance claims data from the Merative MarketScan Research Databases (2001-2022). Patients with blastomycosis were identified using ICD-9/10 codes, and diagnostic delays were estimated using a case-crossover analysis. We estimated the number of potential missed diagnostic opportunities (i.e., healthcare visits prior to the blastomycosis diagnosis with symptoms suggestive of the disease) and identified potential risk factors for delays. A total of 3825 patients with blastomycosis were identified. Of these, 41% experienced at least one missed diagnostic opportunity, with an average of 3.2 missed visits before diagnosis. The average diagnostic delay was 26.82 days (95% confidence interval: 24.57-28.96), with 17% of patients having delays lasting over a month. Missed opportunities occurred primarily in outpatient settings (59.4%). Risk factors for delayed diagnosis included history of diabetes, prior pulmonary conditions (e.g., chronic obstructive pulmonary disease), and respiratory therapies (e.g., antibiotics, inhalers). Diagnostic delays for blastomycosis are common. The association of delays with pre-existing pulmonary conditions underscore the need for heightened clinical suspicion in patients with respiratory symptoms. Education about risk factors for missed opportunities may be helpful in improving timely diagnosis and hopefully will impact patient outcomes.