Incidence of thyroid cancer and medical cost among patients with newly diagnosed thyroid nodules in Korea: A retrospective cohort study using nationwide data

Aims: The frequency of newly diagnosed thyroid nodules is increasing in South Korea. However, few studies have investigated the incidence of thyroid cancer in patients with thyroid nodules using national data. Therefore, this study was conducted to investigate the incidence of thyroid cancer and medical costs among patients newly diagnosed with thyroid nodules in South Korea. Settings and Design: This was a retrospective cohort study. Subjects and Methods: We analyzed the national health claim database, which includes all hospital records and covers almost every population managed by the National Health Insurance System. We selected patients aged 20–120 years with new thyroid nodules in 2008 using the International Classification of Diseases, Tenth Edition codes. We followed the selected cases for at least 2 years after thyroid nodule diagnosis to investigate cancer development and medical costs. Statistical Analysis Used: Frequency analysis was used. Results: We identified 283,844 eligible patients with thyroid nodules. Their mean age was 48 ± 13.2, and 234,388 (82.58%) cases were female. During the median follow-up of 2.4 years, 21,538 (7.6%) patients were diagnosed with thyroid cancer, and 93.5% of them underwent treatment such as thyroidectomy, chemotherapy, or radiotherapy. The average medical cost was 3,996,391 KRW after diagnosis of thyroid cancer. Conclusions: Here, national representative statistics regarding the incidence and medical costs of thyroid nodule and thyroid cancer are presented. The information provided herein will improve understanding of the natural course of thyroid nodules in Asians. Further study is needed to identify the risk factors of thyroid cancer in patients with thyroid nodules.