Effect of hydrogen/oxygen therapy for ordinary COVID-19 patients: a propensity-score matched case-control study

Hydrogen/oxygen therapy contribute to ameliorate dyspnea and disease progression in patients with respiratory diseases. Therefore, we hypothesized that hydrogen/oxygen therapy for ordinary coronavirus disease 2019 (COVID-19) patients might reduce the length of hospitalization and increase hospital discharge rates.

This retrospective, propensity-score matched (PSM) case-control study included 180 patients hospitalized with COVID-19 from 3 centers. After assigned in 1:2 ratios by PSM, 33 patients received hydrogen/oxygen therapy and 55 patients received oxygen therapy included in this study. Primary endpoint was the length of hospitalization. Secondary endpoints were hospital discharge rates and oxygen saturation (SpO₂). Vital signs and respiratory symptoms were also observed.

Findings confirmed a significantly lower median length of hospitalization (HR = 1.91; 95% CIs, 1.25-2.92; p < 0.05) in the hydrogen/oxygen group (12 days; 95% CI, 9-15) versus the oxygen group (13 days; 95% CI, 11-20). The higher hospital discharge rates were observed in the hydrogen/oxygen group at 21 days (93.9% vs. 74.5%; p < 0.05) and 28 days (97.0% vs. 85.5%; p < 0.05) compared with the oxygen group, except for 14 days (69.7% vs. 56.4%). After 5-day therapy, patients in hydrogen/oxygen group exhibited a higher level of SpO₂ compared with that in the oxygen group (98.5%±0.56% vs. 97.8%±1.0%; p < 0.001). In subgroup analysis of patients received hydrogen/oxygen, patients aged < 55 years (p = 0.028) and without comorbidities (p = 0.002) exhibited a shorter hospitalization (median 10 days).

This study indicated that hydrogen/oxygen might be a useful therapeutic medical gas to enhance SpO₂ and shorten length of hospitalization in patients with ordinary COVID-19. Younger patients or those without comorbidities are likely to benefit more from hydrogen/oxygen therapy.