Efficacy of two different dosages of prednisone for treatment of subacute thyroiditis: a single-centre, prospective, randomized, open-label, non-inferiority trial

Introduction: The study aimed to explore the efficacy and safety of low-dose (LD) and regular-dose (RD) prednisone (PDN) for the treatment of subacute thyroiditis (SAT). Material and methods: Patients were randomly allocated using the block randomization method to the 2 groups. The primary outcome was the time required for PDN treatment. Secondary outcomes included percentages of relapse, mean score for the Morisky Medication Adherence Scale-8© (MMAS-8), time required for symptoms to resolve, cumulative PDN dose (mg), and mean erythrocyte sedimentation rate (ESR) at 2 weeks and at baseline. Results: The study cohort included 77 patients, randomized 74 participants, and 68 completed the study. There was no significant difference in the treatment duration between the LD and RD groups (55.31 ± 14.05 vs. 61.25 ± 19.95 days, p = 0.053). The mean difference in the time required for PDN treatment between the LD and RD groups was –1.86 [95% confidence interval (CI) = –10.64 to 6.92] days, which was within the non-inferiority margin of 7 days. There was a significant difference in the mean score for MMAS-8 between the LD and RD groups (5.84 ± 0.88 vs . 5.33 ± 1.12, p = 0.031). Also, there was a significant difference in the cumulative PDN dose between the LD and RD groups (504.22 ± 236.86 vs. 1002.28 ± 309.86, p = 0.046). The ESR at 2 weeks was statistically significant compared to baseline values in both groups, with pre-treatment and post-treatment ESRs of 49.91 ± 24.95 and 17.91 ± 12.60/mm/h, (p < 0.0001) in the LD group and 65.08 ± 21.77 and 17.23 ± 13.61/mm/h (p < 0.0001) in the RD group. Conclusion: Low-dose PDN therapy may be sufficient to achieve complete recovery and better outcomes for SAT. This study is registered with the Chinese Clinical Trial Registry (02/10/2021 ChiCTR2100051762).