Short-term biochemical outcomes after microwave ablation versus parathyroidectomy for primary hyperparathyroidism: an IPTW analysis

Objective To compare the short-term biochemical efficacy and safety of microwave ablation (MWA) and parathyroidectomy (PTX) in patients with primary hyperparathyroidism (PHPT), and to identify independent predictors of treatment failure. Materials and methods This retrospective cohort study included 173 consecutive patients with PHPT treated with MWA (n = 46) or PTX (n = 127) between January 2019 and January 2025. Covariate-balancing propensity score–derived inverse probability of treatment weighting (CBPS-IPTW) was used to balance baseline characteristics. Longitudinal changes in parathyroid hormone (PTH), calcium, and phosphorus were assessed using IPTW-weighted linear mixed-effects models, whereas biochemical treatment failure and safety outcomes were compared using weighted logistic regression with robust standard errors. IPTW-weighted Kaplan–Meier and Cox analyses were exploratory, and factors associated with treatment failure were evaluated using Firth penalized logistic regression. Results After weighting, all covariates were well balanced, with absolute standardized mean differences <0.01. Both treatments produced substantial biochemical improvement. A significant treatment-by-time interaction was observed for PTH (P < 0.001), whereas calcium and phosphorus trajectories did not differ significantly. The weighted risks of treatment failure were 23.8% after PTX and 35.9% after MWA [odds ratio (OR), 1.80; 95% confidence interval (CI), 0.74–4.39], with an absolute risk difference of 12.1 percentage points (95% CI, −7.3 to 31.6). Exploratory Cox analysis showed no significant difference in documented treatment failure (hazard ratio, 1.73; 95% CI, 0.82–3.64). Weighted hypocalcemia risks were 9.2% and 15.5%, respectively (OR, 1.81; 95% CI, 0.50–6.56). Each doubling of baseline PTH was associated with approximately twofold higher odds of treatment failure (OR, 2.02; 95% CI, 1.39–4.09). Conclusion Both MWA and PTX produced substantial short-term biochemical improvement. No significant difference in 6-month treatment failure was detected after CBPS-IPTW adjustment; however, wide confidence intervals precluded conclusions of equivalence or non-inferiority. Baseline PTH may help identify patients at increased risk of incomplete biochemical response, and MWA may be considered for carefully selected patients.