Long-Term Morbidity after Postoperative Hypoparathyroidism in Thyroid Cancer Patients: A Nationwide Population-Based Cohort Study.

BACKGROUND

Chronic hypoparathyroidism (hypoPT) is associated with various systemic morbidities; however, its impact in thyroid cancer patients following thyroidectomy remains unclear. This study evaluated the risk of long-term morbidities in thyroid cancer patients who developed permanent postoperative hypoparathyroidism (PO-hypoPT), compared to those with preserved parathyroid function.

METHODS

This was a retrospective cohort study using South Korea's nationwide claims data encoded in the Observational Medical Outcomes Partnership Common Data Model. Among 217,156 thyroid cancer patients who underwent thyroidectomy from 2013 to 2020, 15,592 patients with PO-hypoPT and 27,906 matched controls with preserved parathyroid function were identified after 1:2 propensity score (PS) matching. Long-term morbidities associated with hypoPT included nephrolithiasis, renal insufficiency, major adverse cardiac events (MACE), seizures, infections, cataracts, and depression. Hazard ratios (HRs) for these morbidities were estimated using Cox proportional hazards regression analysis after large-scale PS matching.

RESULTS

The median follow-up duration in both groups was approximately 5 years. Patients with PO-hypoPT had a significantly higher risk of nephrolithiasis (HR 1.17, confidence interval [CI] 1.04-1.30), renal insufficiency (HR 1.75, [CI 1.50-2.03]), and MACE (HR 1.10, [CI 1.01-1.19]) compared to those with preserved parathyroid function. However, the risks of other long-term morbidities, including seizures, infections, cataracts, and depression, were not significantly different between the two groups. The association between PO-hypoPT and renal insufficiency remained consistent across all subgroups stratified by sex, age, and duration of calcium supplementation.

CONCLUSIONS

PO-hypoPT in thyroid cancer patients is associated with increased long-term morbidity, particularly renal and cardiovascular complications. Long-term monitoring of renal function and cardiovascular health is warranted in this population.