RESUMO
Introduction: The evidence-based use of the oral form of Vitamin C as adjuvant treatment for critically ill COVID-19 patients is lacking worldwide despite its intravenous preparation form being demonstrated to be potentially beneficial in some studies. The present study objective was to evaluate the effects of oral Vitamin C in the treatment of severe COVID-19. Method(s): This was an open-label observational study with propensity score matching on unvaccinated, similar medication history, hospitalized stage-5 severe COVID-19 patients, who were treated with daily 2g, 4g, or 6g of oral Vitamin C respectively from November 2020 to December 2021. The clinical data were collected retrospectively for analysis. The study outcomes were 28-day in-hospital mortality, the proportion of mechanical ventilation-free days (MVFD), the Day 1, Day 3, and Day 7 of both the inflammation progression (c-reactive protein) and the Sequential Organ Failure Assessment score (SOFA). Result(s): A total of 147 patients were recruited. The number of subjects in the 2g, 4g, and 6g Vitamin C groups was 43, 44, and 60 respectively. There was no significant difference in the 28-day mortality (p=0.336), the MVFD (p=0.486), the c-reactive protein level on Day 1 (p=0.856), Day 3 (p=0.977), Day 7 (p=0.462), and the SOFA score on Day 1(p=0.540), Day 3 (p=0.149) and Day 7 (p=0.754) between the three Vitamin C dosing groups. Conclusion(s): The present study showed that the oral form of Vitamin C provided no benefit in reducing stage-5 COVID-19 patients' hospital mortality, the mechanical ventilation requirement, or the overall inflammation progression.