Predictive factors of permanent hypothyroidism after subacute thyroiditis: a systematic review and meta-analysis

Background: Subacute thyroiditis (SAT) is a self-limiting thyroid inflammatory disorder, but some patients develop permanent hypothyroidism, impacting long-term health. We aimed to systematically synthesize evidence on factors associated with permanent hypothyroidism after SAT. Methods: . Results: Ten studies involving 1294 patients were included. Higher free triiodothyronine (FT3) levels (mean difference = 1.85, 95% CI: 0.60-3.09; Z = 2.91, P = 0.004; I² = 0%) and positive thyroglobulin antibodies (TgAb) (OR = 2.57, 95% CI: 1.35-4.88, P = 0.004; I² = 57%, τ² = 0.13) were significantly associated with an increased risk of permanent hypothyroidism after SAT. Corticosteroid therapy was associated with a lower odds of permanent hypothyroidism compared with NSAID-based management (OR = 0.40, 95% CI: 0.23-0.70, P = 0.001; I² = 36%). Conclusions: FT3, TgAb positivity and treatment modality are associated with the risk of permanent hypothyroidism following SAT. Compared with NSAID-based management, corticosteroid therapy is associated with lower odds of developing permanent hypothyroidism. These findings support early identification of high-risk patients and personalized follow-up strategies. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier CRD420251064643.