BACKGROUND: We aimed to characterize the association between differentiated thyroid cancer (DTC) patient insurance status and appropriateness of therapy (AOT) regarding extent of thyroidectomy and radioactive iodine (RAI) treatment.

METHODS: The National Cancer Database was queried for DTC patients diagnosed between 2010 and 2016. Adjusted odds ratios (AOR) for AOT, as defined by the American Thyroid Association guidelines, and hazard ratios (HR) for overall survival (OS) were calculated. A difference-in-differences (DD) analysis examined the association of Medicaid expansion with outcomes for low-income patients aged <65.

RESULTS: A total of 224,500 patients were included. Medicaid and uninsured patients were at increased risk of undergoing inappropriate therapy, including inappropriate lobectomy (Medicaid 1.36, 95% confidence interval [CI]: 1.21-1.54; uninsured 1.30, 95% CI: 1.05-1.60), and under-treatment with RAI (Medicaid 1.20, 95% CI: 1.14-1.26; uninsured 1.44, 95% CI: 1.33-1.55). Inappropriate lobectomy (HR 2.0, 95% CI: 1.7-2.3, P < .001) and under-treatment with RAI (HR 2.3, 95% CI: 2.2-2.5, P < .001) were independently associated with decreased survival, while appropriate surgical resection (HR 0.3, 95% CI: 0.3-0.3, P < .001) was associated with improved odds of survival; the model controlled for all relevant clinico-pathologic variables. No difference in AOT was observed in Medicaid expansion versus non-expansion states with respect to surgery or adjuvant RAI therapy.

CONCLUSION: Medicaid and uninsured patients are at significantly increased odds of receiving inappropriate treatment for DTC; both groups are at a survival disadvantage compared with Medicare and those privately insured.