Modeling the Relationship of Age With Hypocalcemia Following Total Thyroidectomy: A NSQIP Analysis

To characterize the relationship between age and hypocalcemia risk following total thyroidectomy and identify critical age-related transition points across the lifespan.

The American College of Surgeons National Surgical Quality Improvement Program Thyroidectomy Targeted database was queried for 21,109 adult patients (18+) from 2016 to 2023 who underwent total thyroidectomy. Multivariate regressions utilizing age, sex, race/ethnicity, BMI, surgical specialty, ASA classification, and surgical indication were used to assess odds of hypocalcemia within 30 days of surgery. Additionally, age-stratified analyses, generalized additive modeling (GAM), and segmented regression were used to assess odds of hypocalcemia.

Age was independently associated with 2% decreased odds of hypocalcemia per year older (OR, 0.98; 95% CI, 0.98-0.99; p-value < 0.001). GAM and systematic evaluation of 1,683,217 segmented regression models identified six key inflection points at ages 26, 35, 39, 51, 54, and 71, with hypocalcemia risk characterized by sharp changes at these transition points and gradual changes between them. Inflection points in early adulthood were the most consistent across models, while those in older age showed greater variability, suggesting increasing physiological heterogeneity with advancing age. Risk stabilized after age 65 with no significant differences between consecutive age groups.

Hypocalcemia risk following total thyroidectomy follows a nonlinear age-dependent pattern with identifiable transitions, challenging simple continuous or categorical age modeling. Risk stabilizes after the mid-sixties, though very elderly patients should not be assumed to have lower risk due to advanced age alone. These findings support development of age-tailored risk stratification tools for more personalized perioperative calcium management.

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