Changes in Multisystem Morbidity in Thyroid Cancer after the 2015 ATA Guideline: A Nationwide Population-Based Retrospective Cohort Study

BACKGROUND: As survivorship has become increasingly important in differentiated thyroid cancer (DTC), the 2015 American Thyroid Association (ATA) guideline introduced a more risk-adapted and less intensive approach to management. However, evidence regarding the association between guideline-driven de-intensification and non-cancer-specific multisystem morbidity remains limited. METHODS: = 29,408) the 2015 ATA guideline. Outcome-specific 1:1 propensity score-matched analytic sets were constructed. The primary outcomes were composite cardiovascular/cerebrovascular, composite skeletal, and composite neurocognitive/psychiatric outcomes, as well as all-cause mortality. Secondary analyses examined the individual components of each composite outcome. Time-to-event analyses were performed using multivariable Cox proportional hazards models. RESULTS: After matching and adjustment, the postguideline period demonstrated lower risks of composite skeletal outcomes (hazard ratio [HR] = 0.83; confidence interval [CI] 0.69-0.99) and composite neurocognitive/psychiatric outcomes (HR = 0.73; CI 0.69-0.77). Composite cardiovascular/cerebrovascular outcomes did not differ significantly between periods; however, secondary analyses showed lower risks of atrial fibrillation (HR = 0.62; CI 0.50-0.76), myocardial infarction (HR = 0.81; CI 0.66-0.99), and stroke (HR = 0.56; CI 0.49-0.63). All-cause mortality was similar between periods. CONCLUSIONS: During the post-2015 ATA guideline period, there was a lower burden of non-cancer-specific multisystem morbidity among patients undergoing total thyroidectomy for thyroid cancer. These findings support the relevance of guideline-recommended, risk-adapted de-intensification strategies for improving long-term survivorship outcomes in DTC.