Background: The management of thyroid nodules >4 cm with benign cytology after fine-needle aspiration biopsy (FNAB) is controversial. FNAB is associated with a high false-negative rate in this setting, and may result in a delayed diagnosis and management of thyroid cancer. However, the majority of these nodules are benign. Therefore, the objective of this study was to determine the cost-utility of observation versus surgical management for thyroid nodules >4 cm with benign cytology after FNAB.
Methods: A microsimulation model comparing routine thyroid lobectomy with observation for low-risk patients with >4 cm thyroid nodules with benign FNAB cytology was constructed. Costs, quality-adjusted life-years (QALYs), and life-years gained were calculated over a lifetime time horizon from a U.S. Medicare perspective.
Results: The proportion of patients undergoing thyroid lobectomy for benign final pathology was 40% in the observation strategy versus 66% in the surgical strategy (p < 0.001). Overall, the surgical strategy was associated with higher lifetime costs compared with the observation strategy (incremental difference: + US$12,992 [confidence interval (CI) 13,042-13,524]), but also more QALYs (+0.12 QALYs [CI 0.02-0.24]) and longer life expectancy (+1.67 years [CI 1.00-2.41]). Incremental lifetime costs were lower for patients <55 years compared with those ≥55 years (+11,181 vs. +14,811, p < 0.001). The probability of cost-effectiveness of the surgical strategy was 49% at a $100k/QALY threshold or 65% at a $100k/life-year gained threshold.
Conclusions: Routine thyroid lobectomy is associated with improved outcomes at an acceptable cost compared with observation for thyroid nodules >4 cm with benign cytology after FNAB. Surgical resection may be a cost-effective strategy to rule out malignancy in these nodules.