Descriptive analysis of Cycle Threshold in patients with hematologic malignancies infected with SARS-COV-2

SARS-CoV-2 has caused over 200 million documented infections, more than 4 million deaths, and unprecedented consequences worldwide. The cycle threshold (Ct), the number of amplification cycles required to obtain a product detectable through fluorescence during a quantitative RT-PCR test, is an indirect measurement of viral load. Patients with hematologic malignancies have an increased risk of death by the SARS-CoV-2.

We conducted a retrospective, observational, descriptive analysis of the Ct obtained from patients with history of hematologic malignancies who tested positive for SARS-CoV-2 in our hospital, from March 3rd, 2020, to August 17th, 2021. We used the mean Ct at diagnosis. 15 adults, with previous diagnosis of lymphomas, acute leukemias and chronic lymphocytic leukemia, were included. 9 of the 15 patients (60 %) developed pneumonia, 6 of them required supplementary oxygen and 5 mechanical ventilation. 5 patients died between 7-86 days from symptom onset. Ct was lower among the group of patients who died (15.5 cycles; SD= 2.28, CI95%= 9.17-21.86) compared with those who survived (20.2 cycles; SD= 8.87, CI95%= 13.9-26.6). Ct was also lower in the pneumonia group (18.2 cycles; SD= 2.28, CI95%= 12.98-23.51) than in the no-pneumonia group (19.3 cycles; SD= 4.11; CI95%= 8.73-29.9).

Ct was lowest in severe forms of CoViD-19. Further studies with larger populations of patients with hematologic malignancies could establish the validity of Ct as a quantitative laboratory determination as a course-prediction and infectivity tool.