Background: Pulmonary aspergillosis remains highly lethal despite modern therapy. Although polymerase chain reaction (PCR) has enhanced detection, the clinical significance of its cycle threshold (Ct) values is unclear. The key problem is the lack of validation of Ct values for assessing fungal burden or predicting outcomes, limiting their diagnostic and prognostic utility. Methods: We conducted a retrospective cohort study of 154 adult patients diagnosed with pulmonary aspergillosis at a tertiary medical center in Taiwan (2021– 2024). All patients had a positive Aspergillus PCR from a respiratory specimen. We used receiver operating characteristic (ROC) curve analysis to determine an optimal Ct cutoff for predicting 30-day all-cause mortality and multivariable logistic regression to identify independent predictors. Results: Among 154 patients (mean age 70.5 ± 13.5 years; 48.1% female), the optimal Ct cutoff for predicting 30-day mortality was 30.7 (AUC = 0.65, 95% CI 0.56– 0.73). Patients with a Ct value < 30.7 had significantly higher 30-day mortality than those with a Ct ≥ 30.7 (71.2% vs 43.1%, p = 0.002). After adjusting for clinical and laboratory confounders, a Ct value < 30.7 remained the independent predictor of mortality (adjusted OR 3.07; 95% CI 1.27– 7.39; p = 0.012). Conclusion: A low Aspergillus PCR Ct value is an independent predictor of 30-day mortality in patients with pulmonary aspergillosis. While its discriminative ability is moderate, the Ct value may serve as a valuable predictor to aid in early risk stratification, when interpreted within the overall clinical context. Keywords: Aspergillus , PCR, cycle threshold, fungal burden, risk stratification
Huang et al. (Sun,) studied this question.