Comparison of the therapeutic effects of 15 mg and 30 mg initial daily prednisolone doses in patients with subacute thyroiditis: a multicenter, randomized, open-label, parallel-controlled trial

Current guidelines recommendations for the initial dose of prednisolone (PSL) in the treatment of subacute thyroiditis (SAT) are based on low-quality studies. We designed a randomized controlled trial (RCT) to compare the efficacy and safety of using a low initial dose of PSL with a standard initial dose of PSL in SAT patients. This open-label RCT was conducted at five hospitals in China from June 2019 to January 2022. SAT patients with moderate-to-severe pain or a poor response to non-steroidal anti-inflammatory drugs (NSAIDs) were randomly assigned in a 1:1 ratio to the experimental and control groups. The initial dose of PSL was 15 mg/d in the experimental group and 30 mg/d in the control group. The primary outcome was the total duration of PSL treatment, with non-inferiority prespecified with a margin of 7 days. Clinical trial registration number: ChiCTR1900023884. The full analysis set included 60 patients (30 in each group). The mean duration of PSL treatment in the experimental and control group was 34.62 ± 14.12 and 41.18 ± 16.89 days, respectively, meeting the non-inferiority criterion (pnon-inferiority = 0.0006). The total dose of PSL used in the experimental group was lower than in the control groups (330 vs 595 mg, p The initial dose of 15 mg/d of PSL was not inferior to the dose of 30 mg/d in terms of efficacy and showed a similar safety profile. A low initial dose of PSL could be recommended for Chinese adult SAT patients who have a suboptimal response using NSAIDs or experience moderate-to-severe pain.KEY MESSAGESLow initial dose (15 mg/d) of prednisolone was non-inferior to the standard initial dose of prednisolone (30 mg/d) in treatment duration, time to pain relief, or the prevalence of hypothyroidism, recurrence, and adverse reactions in the treatment of subacute thyroiditis.Patients with subacute thyroiditis administered a low initial dose of prednisolone had a lower total dose of prednisolone compared to those receiving the standard dose of prednisolone. Low initial dose (15 mg/d) of prednisolone was non-inferior to the standard initial dose of prednisolone (30 mg/d) in treatment duration, time to pain relief, or the prevalence of hypothyroidism, recurrence, and adverse reactions in the treatment of subacute thyroiditis. Patients with subacute thyroiditis administered a low initial dose of prednisolone had a lower total dose of prednisolone compared to those receiving the standard dose of prednisolone.