Comparative effectiveness of tocilizumab vs standard care in patients with severe COVID-19-related pneumonia: a retrospective cohort study utilizing registry data as a synthetic control

BACKGROUND: The severity of coronavirus disease 2019 (COVID-19) infections has led to the development of several therapeutic agents, with tocilizumab becoming increasingly used to treat patients with COVID-19-related pneumonia. This study compared the use of tocilizumab treatment with the standard of care (SOC) to determine its efficacy against severe COVID-19-related pneumonia in Japan. METHODS: This retrospective cohort study was designed to evaluate the efficacy of tocilizumab in two different databases: the JA42434 single-arm study and COVID-19 Registry Japan (COVIREGI-JP), with a synthetic control group from the COVIREGI-JP cohort as a benchmark for the tocilizumab group. The study’s primary objective was to evaluate the efficacy of tocilizumab in treating severe COVID-19-related pneumonia compared to the SOC among patients included in the above two databases. The SOC group was extracted as the synthetic control group using exact matching and a propensity score matching in sequence per subject. As a secondary objective, the efficacy of tocilizumab compared to the SOC was evaluated exclusively among patients included in the COVIREGI-JP database. In each objective, the primary endpoint was defined as the time to discharge or the status of awaiting discharge. RESULTS: For the primary endpoint, the hazard ratio (HR) of the tocilizumab group against the SOC group was 1.070 (95% confidence interval [CI]: 0.565–2.028). The median time from Study Day 1 to discharge or the state of awaiting discharge was 15 days in the tocilizumab group and 16 days in the SOC group. The HRs for the secondary endpoints, namely, time to improvement in the clinical state, time to clinical failure, and time to recovery, were 1.112 (95% CI: 0.596–2.075), 0.628 (95% CI: 0.202–1.953), and 1.019 (95% CI: 0.555–1.871), respectively. Similarly, the HR of the primary endpoint for the secondary objective was 0.846 (95% CI: 0.582–1.230). CONCLUSIONS: Tocilizumab did not demonstrate a positive effect on time to discharge or the state of awaiting discharge. Furthermore, no statistically significant differences in other clinical outcomes, such as time to improvement in the clinical state, time to clinical failure, and time to recovery, were observed among the groups. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12879-023-08840-6.