Optimizing Antithyroid Drug Duration in Graves’ Disease with Low TRAb: Evidence for Shorter Therapy

Highlight

This study evaluates relapse outcomes following shorter versus standard antithyroid drug (ATD) therapy in Graves’ disease patients with lower baseline thyrotropin receptor antibody (TRAb) levels. It finds that ATD courses shorter than 12 months yield relapse rates broadly comparable to the guideline-recommended 12-18 months, a finding that supports TRAb-guided individualized treatment duration.

Study Background

Graves’ disease is an autoimmune thyroid disorder characterized by hyperthyroidism due to stimulating thyrotropin receptor antibodies (TRAbs). Antithyroid drugs (ATDs), including methimazole and propylthiouracil, remain first-line treatments for many patients. However, the optimal duration of ATD therapy remains uncertain. Current clinical guidelines typically recommend 12-18 months of treatment before cessation, but practice varies. Individualized treatment strategies, especially guided by baseline TRAb levels, have been suggested to refine duration and possibly reduce exposure to ATDs and associated adverse effects.

Lower TRAb titers at diagnosis have been associated with a more favorable prognosis and lower relapse risk after stopping therapy, which may present an opportunity to shorten treatment safely in this subgroup. However, robust evidence comparing relapse rates between shorter and standard ATD courses in patients with low baseline TRAb remains limited.

Study Design

This retrospective observational study analyzed real-world data from adult patients with Graves’ disease treated at a single center. Eligible patients had baseline TRAb levels between >1.8 and <10.0 U/L, indicating lower antibody burden but active disease warranting treatment. Patients received ATDs either for a shorter duration (<12 months) or the standard duration (12-18 months). The primary outcome was the incidence of disease relapse within 12 months after ATD discontinuation.

The analysis employed a propensity score methodology to account for baseline differences between groups. Three analytic approaches were used: unadjusted comparison, inverse-probability-of-treatment weighting (IPTW) with 369 patients, and 1:1 propensity score matching (PSM) involving 104 matched pairs. Secondary endpoints included long-term relapse rates (median follow-up 58 months), TRAb levels at cessation, and restricted mean survival time (RMST) over 60 months.

Key Findings

The primary analysis showed relapse within 12 months occurred in 17.2% (23/134) of the shorter therapy group and 20.4% (48/235) in the standard therapy group. The IPTW-adjusted risk difference was -1.5% (95% confidence interval [CI] -11.0% to +8.0%), suggesting the shorter course was non-inferior within a 10% but not a more stringent 5% margin. The unadjusted comparison (-3.2%) met both non-inferiority margins, whereas the PSM analysis (+2.9%, 95% CI -7.3% to +13.1%) did not meet either margin due to reduced precision from a smaller matched sample.

Long-term analyses demonstrated similar relapse risk between groups. The IPTW-adjusted hazard ratio for relapse over median 58 months was 0.92 (95% CI 0.65-1.31), indicating no significant difference. RMST over 60 months favored the shorter course by +3.2 months (95% CI -2.1 to +8.4), also not statistically significant. TRAb levels at ATD cessation were comparable between groups, supporting that antibody status at treatment end was not adversely affected by shorter therapy.

The safety profile was not explicitly detailed but shorter treatment durations may potentially reduce adverse events related to ATD exposure, such as agranulocytosis and hepatic toxicity, though this requires confirmation in prospective studies.

Expert Commentary

This study offers valuable real-world evidence supporting the safety of individualized ATD duration guided by baseline TRAb levels in Graves’ disease. While conventional guidelines advocate for 12-18 months of therapy, these findings suggest that a shorter course may be reasonable in patients with mild antibody elevation at diagnosis, helping to minimize treatment burden without compromising relapse risk significantly.

Nonetheless, the study’s observational design and residual imbalances despite propensity adjustments limit the conclusiveness of results. The lack of blinding and potential confounders inherent to retrospective data necessitate prospective randomized controlled trials to definitively establish non-inferiority of shorter regimens.

Moreover, the 5% non-inferiority margin was not met, highlighting the importance of cautious interpretation. The 10% margin outcome may reflect clinical acceptability in certain contexts but should not be generalized without further validation. The study nicely corroborates the prognostic utility of TRAb levels and supports evolving strategies toward personalized treatment duration in Graves’ disease management.

Conclusion

In patients with Graves’ disease and lower baseline TRAb levels, antithyroid drug therapy for less than 12 months yields relapse outcomes broadly comparable to the standard 12-18 months. Although the strict 5% non-inferiority margin was not met, results within a 10% margin support consideration of TRAb-guided treatment individualization. This approach may optimize patient care by reducing unnecessary drug exposure. Prospective randomized studies are warranted to confirm these findings and inform clinical guidelines.

Funding and ClinicalTrials.gov

The original study’s funding sources were not explicitly stated, nor was a clinical trial registration mentioned, consistent with observational real-world data analysis.

References

1. Razvi S, Holley M, Wheeler H, Vernazza J, Stewart K, Pearce SHS, Narayanan K, Tsatlidis V. Shorter Versus Standard Antithyroid Drug Therapy in Graves’ Disease with Lower Baseline Thyrotropin Receptor Antibody (TRAb) Levels: Relapse Outcomes from a Propensity-Weighted Analysis. Thyroid. 2026 Jul 21:10507256261470303. PMID: 42478510.

2. Ross DS, et al. 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis. Thyroid. 2016;26(10):1343-1421.

3. Smith TJ, Hegedüs L. Graves’ Disease. N Engl J Med. 2016;375(16):1552-1565.

4. Gullo D, et al. High Rate of Spontaneous Remission of Graves’ Disease in Patients with Low or Undetectable TSH Receptor Antibodies. J Clin Endocrinol Metab. 2012;97(10):3853-3858.