Cycle threshold value and coronavirus disease 2019 clinical type among smokers and nonsmokers reveal no significant association despite clinical type shows smokers are at high risk: A retrospective study

Background: Emerging epidemiological studies indicate a paradoxical association between smoking and coronavirus disease 2019 (COVID-19). This retrospective study aimed to investigate the association between cycle threshold (Ct) values and clinical type among COVID-19-positive smokers and nonsmokers. Methods: The study was conducted from October 3, 2020, to October 3, 2022. Five hundred and sixty COVID-19 patients were enrolled, which included 320 smoking group (SG) and 240 non-SG (NSG). Demographic and clinical features were acquired, and comparison was based drawn on gender, age, Ct range, and clinical type (mild/mild-moderate/severe COVID-19). COVID-19 was confirmed by real time reverse-transcription polymerase chain reaction test based on Ct value below 35. Results: Initial evaluation revealed no significant association between Ct range and clinical type either within or between SG and NSG. Follow-up at 7/14 days revealed no significant difference between the groups for Ct range/clinical type; however, within groups Ct range showed a clear change towards higher values. The recovery rate was also evaluated which displayed no difference at 7 days while at 14 days' recover rate was 47.5% for SG and 80.0% for NSG. Moreover, in both groups un-recovered patients were mostly observed either in mild-moderate and severe COVID state; however, SG showed more patients in mild-moderate group and longer discharge time. Conclusions: We found that Ct value and clinical type have no significant association in COVID-19 smokers versus nonsmokers and smokers are at high risk and take a longer time to recover from COVID.