Autoimmune thyroiditis incidence in a large population-based study in northeastern Italy

Area of Science:

• Endocrinology
• Epidemiology
• Public Health

Background:

• Iodine status in the Veneto region, Italy, has improved over the past decade.
• Understanding the incidence trends of autoimmune thyroiditis (AT) is crucial for public health planning.

Purpose of the Study:

• To estimate the incidence of autoimmune thyroiditis (AT) in the Veneto region between 2012 and 2022.
• To investigate the association between improved iodine status and AT incidence trends.

Main Methods:

• A retrospective, population-based study utilizing Veneto's population registry and administrative health databases.
• Incident hyperthyroidism cases were identified from 2013 to 2022 to exclude prevalent cases.
• Standardized incidence rates (IR) per 10,000 person-years were calculated by age and sex.

Main Results:

• A total of 65,379 incident AT cases were identified (IR: 13.38), with females exhibiting a 5.44-fold higher incidence than males.
• Overall IR decreased from 15.86 in 2013 to 12.35 in 2022, a decline primarily observed in females, especially those aged 15-54 years.
• A notable out-of-trend decrease in AT incidence occurred in 2020, coinciding with the SARS-CoV-2 pandemic.

Conclusions:

• Autoimmune thyroiditis incidence has declined in the Veneto region over the last decade, paralleling improvements in iodine status.
• The reduction in AT incidence was statistically significant only in females, particularly those of reproductive age.
• The SARS-CoV-2 pandemic temporarily impacted AT incidence trends, with rates realigning subsequently.