Thymosin α1 therapy in critically ill patients with COVID-19: A multicenter retrospective cohort study

COVID-19 characterized by refractory hypoxemia increases patient mortality because of immunosuppression effects. This study aimed to evaluate the efficacy of immunomodulatory with thymosin α1 for critical COVID-19 patients.

This multicenter retrospective cohort study was performed in 8 government-designated treatment centers for COVID-19 patients in China from Dec. 2019 to Mar. 2020. Thymosin α1 was administrated with 1.6 mg qd or q12 h for >5 days. The primary outcomes were the 28-day and 60-day mortality, the secondary outcomes were hospital length of stay and the total duration of the disease. Subgroup analysis was carried out according to clinical classification.

Of the 334 enrolled COVID-19 patients, 42 (12.6%) died within 28 days, and 55 (16.5%) died within 60 days of hospitalization. There was a significant difference in the 28-day mortality between the thymosin α1 and non-thymosin α1-treated groups in adjusted model (P = 0.016), without obvious differences in the 60-day mortality and survival time in the overall cohort (P > 0.05). In the subgroup analysis, it was found that thymosin α1 therapy significantly reduced 28-day mortality (Hazards Ratios HR, 0.11, 95% confidence interval CI 0.02-0.63, P=0.013) via improvement of Pa0₂/FiO₂ (P = 0.036) and prolonged the hospital length of stay (P = 0.024) as well as the total duration of the disease (P=0.001) in the critical type patients, especially those aged over 64 years, with white blood cell >6.8×10⁹/L, neutrophil >5.3×10⁹/L, lymphocyte < 0.73 × 10⁹/L, PaO₂/FiO₂ < 196, SOFA > 3, and acute physiology and chronic health evaluation (APACHE) II > 7.

These results suggest that treatment with thymosin α1 can markedly decrease 28-day mortality and attenuate acute lung injury in critical type COVID-19 patients.