OBJECTIVES: Invasive aspergillosis (IA) is a fungal infection that has been linked to significant morbidity and mortality in severely ill immunocompromised patients. The gold standards for diagnosing IA, culture and microscopy, have limited sensitivity. When treating patients who have risk factors for the condition, the approach is frequently empirical. The galactomannan (GM) test may influence the prognosis of patients with suspected IA by enabling early diagnosis, which lowers the risk of needless therapy, adverse effects, and mortality. This study's goal was to evaluate the clinical and economic effects of integrating the GM test into the Brazilian Public Health System (SUS).

METHODS: We investigated five strategies using life years gained (LYG) and “needless therapies avoided” as efficacy outcomes in a Markov model.: (i) culture; (ii) GM test with 0.5 optical density cutoff; (iii) GM test 1.0 cutoff; (iv) GM test 0.5 + culture; (v) GM test 1.0 + culture. Strategies were also compared according to the sample: bronchoalveolar lavage (BAL) or serum. The accuracy of these strategies was based on systematic reviews. The costs are based on a SUS perspective. Additionally, univariate and probabilistic analyses were carried out.

RESULTS: When compared to culture, all GM test simulations revealed an increase in LYG and expenses. No matter the sample or cutoff, all demonstrated an incremental cost-effectiveness ratio of under USD 950.00. When comparing the cutoffs, the 0.5 was associated with a marginal improvement in LYG (0.02 (serum) to 0.03 (BAL)), but it was also associated with a rise in expenses (USD 43 (serum) to USD 97/ patient (BAL)) and the proportion of patients receiving unnecessary treatment (4.5% (serum) to 10.1% (BAL) false positives).

CONCLUSIONS: The findings demonstrate that adding the GM test to the SUS would be cost-effective and improve survival rates. Higher GM cutoffs are associated with fewer inappropriate prescriptions without substantial clinical benefit losses.