[Thymosin alpha 1 for the adjuvant treatment of coronavirus disease 2019: a retrospective cohort study].

Objective: To evaluate the effect of thymosin alpha 1 on the prognosis of patients with coronavirus disease 2019 (COVID-19).

Methods: A retrospective cohort study was performed to collect clinical data of 95 patients treated by Shanghai Aid Medical Team in Wuhan Third Hospital during January 31, 2020 and March 4, 2020, who were confirmed COVID-19. They were divided into two groups according to whether they were treated with thymosin alpha 1 after admission. The 28-day mortality (primary outcome), and 28-ventilator-free-day, lymphocyte count (LYM) level, C-reactive protein (CRP) level (secondary outcomes) were compared between two groups. Survival analysis was performed using the Kaplan-Meier curve. The effect of thymosin alpha 1 on 28-day survival was evaluated with Cox regression model.

Results: Among the 95 patients, there were 31 cases in thymosin group and 64 cases in non-thymosin group; 29 patients died 28 days after admission, including 11 cases (35.5%) in thymosin group and 18 cases (28.1%) in non-thymosin group. Kaplan-Meier survival curve showed that thymosin alpha 1 could improve the 28-day survival of patients with COVID-19, but the univariate Cox model analysis showed that the difference was not statistically significant [hazard ratio (HR) = 0.48, 95% confidence interval (95%CI) was 0.20-1.14, P = 0.098]; multivariate Cox model analysis showed that thymosin alpha 1 was the factor to improve the 28-day mortality (HR = 0.15, 95%CI was 0.04-0.55, P = 0.004), old age (HR = 1.10, 95%CI was 1.05-1.15, P < 0.001), accompanied by chronic renal dysfunction (HR = 42.35, 95%CI was 2.77-648.64, P = 0.007), decrease of LYM at admission (HR = 0.15, 95%CI was 0.04-0.60, P = 0.007) and the use of methylprednisolone (HR = 4.59, 95%CI was 1.26-16.67, P = 0.021) were also risk factors for the increase of 28-day mortality. The use of immunoglobulin and antiviral drugs abidol and ganciclovir did not affect the 28-day mortality. After adjustment for age, gender, LYM and other factors, weighted multivariate Cox analysis model showed thymosin alpha 1 could significantly improve the 28-day survival of COVID-19 patients (HR = 0.45, 95%CI was 0.25-0.84, P = 0.012). In terms of secondary outcomes, no statistical difference (all P > 0.05) was found between two groups in days without ventilator at 28 days after admission (days: 17.97±13.56 vs. 20.09±12.67) and the increase of LYM at 7 days after admission [×10/L: -0.07 (-0.23, 0.43) vs. 0.12 (-0.54, 0.41)]. But the decrease of CRP at 7 days after admission in thymosin alpha group was significantly greater than that in non-thymosin group [mg/L: 39.99 (8.44, 82.22) vs. 0.53 (-7.78, 22.93), P < 0.05].

Conclusion: Thymosin alpha 1 may improve 28-day mortality and inflammation state in COVID-19 patients.