Understanding epidemiology and the factors leading to thyroid nodule diagnosis might help alter the course of the thyroid cancer epidemic. Population-based study using the Rochester Epidemiology Project database between 2003 and 2006. Patients with thyroid nodules who underwent ultrasound guided fine needle aspiration biopsy were included. We identified 453 patients with 520 thyroid nodules undergoing ultrasound guided fine needle aspiration. Patients were mostly women (n: 349, 77 %) with a mean age of 52 (standard deviation 17) years. The age-adjusted and sex-adjusted incidence of ultrasound guided fine needle aspiration-thyroid nodules between 2003 and 2006 was 89 (95 % confidence interval, 80-97) per 100,000 person-years; the incidence in women was 130 (95 % confidence interval, 117-144), and for men 43 (95 % confidence interval, 35-52) per 100,000 person-years. The incidence of ultrasound guided fine needle aspiration-thyroid nodules increased by 42 %, from 68 (95 % confidence interval, 54-82) in 2003 to 97 (95 % confidence interval, 80-113) per 100,000 person-years in 2006. The group with the highest incidence was patients between 70 and 79 years of age, 258 per 100,000 person-years. Most ultrasound guided fine needle aspiration-thyroid nodules were found in asymptomatic patients (n: 371, 82 %) by physical examination (n: 197, 43 %) or on imaging studies performed for non-thyroid issues (n: 108, 24 %). Women were more likely to have nodules detected by palpation (45 %), whereas imaging and physical examination contributed similarly in men (39 and 38 %). There is a large and rapid increase in the ultrasound guided fine needle aspiration-thyroid nodules, particularly among women and elderly patients which mirrors the trends observed in thyroid cancer. Most thyroid nodules were found in asymptomatic patients as a result of routine physical examination or imaging.
Keywords: Incidence; Thyroid nodule; Triggers.