Clinical Significance of Cycle Threshold (Ct) Values for Predicting COVID‐19 Patient Outcome

Quantitative PCR (qPCR) is a highly accurate molecular tool widely used for the diagnosis of infectious diseases, including SARS‐CoV‐2 infection. Among its key outputs, the Cycle Threshold (Ct) value indicates the number of amplification cycles required to detect the target genetic material, with lower Ct values reflecting higher concentrations of viral nucleic acids. In this retrospective study, we analyzed data from 16,372 patients diagnosed with COVID‐19 caused by SARS‐CoV‐2 using RT‐qPCR in Durango, Mexico, between 2021 and 2023. Patients were classified into home monitoring, in treatment, and severe cases, and survival status was recorded. ANOVA showed significantly lower Ct values in severe cases (Ct < 25, p < 0.001). The Student’s t‐test also identified significant differences between survivors and deceased patients. A binary logistic regression, adjusted for age, sex, symptoms, and comorbidities, confirmed that Ct < 25 remained strongly associated with disease severity (OR = 2.06; 95% CI: 1.69–2.50; p < 0.001). ROC analysis demonstrated excellent predictive ability (AUC = 0.95), supporting the clinical utility of Ct values as a decision‐making tool.