Cost-Effectiveness of Active Surveillance Compared to Early Surgery of Small Papillary Thyroid Cancer: A Retrospective Study on a Korean Population

Abstract

Background: Recently, active surveillance (AS) has been introduced as an alternative to early surgery (ES) for the management of papillary thyroid microcarcinoma (PTMC), because of its indolent features and low mortality. However, its cost effects have not been determined and the findings of current studies differ, according to each country's medical system.

Methods: A Markov model was constructed to compare the cost-effectiveness of AS and ES, based on a reference case of a 40-year-old patient diagnosed with PTMC. Costs and transition probabilities were derived from previous clinical studies in Korean populations, and the incremental cost-effectiveness ratio (ICER) and net monetary benefit (NMB) were calculated. The willingness-to-pay (WTP) threshold was set at USD 100,000 per quality-adjusted life year (QALY) gained. Sensitivity analyses were conducted to address the uncertainties in the model's variables.

Results: From the base scenario, the cumulative costs and effectiveness were both higher in ES than AS. The ICER for ES, compared with AS, was USD 6,619.86/QALY, lower than the set WTP. The NMB difference between AS and ES increased across the stages (USD 5,980 at the first stage and USD 159,667 at the last stage). The ICER increased along with decreasing age and increasing cost of surgery. The higher the ES utility score and the lower that of AS, the more cost-effective ES, with WTP set at USD 30,000.

Conclusion: In the current Korean medical system, ES is more cost-effective than AS. ES is more cost-effective as it is diagnosed at young age and followed-up for a long time.

Keywords: Active Surveillance; Cost-Effectiveness Analysis; Endocrine Surgical Procedures; Papillary Thyroid Microcarcinoma; Quality of Life.

Fig. 1. The ICER and the NMB according to each stage. (A) The ICER decreased according to the stages. (B) The blue bar represents the NMB of AS and the orange bar represents the NMB of ES. The difference in NMB is increasing with each stage, and is represented as a gray curve.

ICER = incremental cost effectiveness ratio, NMB = net monetary benefit, QALY = quality-adjusted life year, AS = active surveillance, ES = early surgery.

Fig. 2. The results of the one-way sensitivity analysis. (A) The ICER according to age at diagnosis; the ICER decreases with age. (B) The ICER according to surgery costs; the higher surgery costs, the higher the ICER. (C) The ICER according to cost of ultrasonography; the higher the ultrasonography cost, the higher the ICER. (D) The NMB according to mortality after lobectomy. At base case (0.0039), the NMB of ES is higher than NMB of AS. At 0.0139, however, the two lines cross. If the mortality is higher than 0.0139, the NMB of AS is higher than the NMB of ES.

ICER = incremental cost effectiveness ratio, NMB = net monetary benefit, ES = early surgery, AS = active surveillance, QALY = quality adjusted life year.

Fig. 3. The cost-effectiveness acceptability curve and the results of the two-way sensitivity analysis. (A) With the cost-effectiveness acceptability curve, the iterations were reversed when WTP is about USD 5,000. (B) The higher the utility score of ES (≥ about 0.865) and the lower the utility of AS (< about 0.934), the higher the cost-effectiveness of ES, with WTP set at USD 30,000. (C) With lower WTP (USD 5,000), AS was slightly more cost-effective, but the ES was still the most cost-effective.

WTP = willingness-to-pay, ES = early surgery, AS = active surveillance.