Temporal Trends in Thyroid Nodule Size on Ultrasonography: A Systematic Review and Meta-Analysis

Area of Science:

• Endocrinology
• Radiology
• Oncology

Background:

• Growing concern over thyroid cancer overdetection.
• Recent updates to thyroid nodule risk stratification and guidelines aimed to improve diagnostic accuracy.
• The impact of these changes on reported thyroid nodule size via ultrasonography remains unclear.

Purpose of the Study:

• To evaluate changes in reported thyroid nodule size since 1990.
• To compare trends in nodule size between diagnostic and screening ultrasonography studies.

Main Methods:

• Systematic review and meta-analysis of original research studies.
• Included adults undergoing their first thyroid ultrasonography.
• Searched PubMed, SCOPUS, CENTRAL, and CINAHL from January 1990 to March 2021.
• Used mixed-effects meta-regression to analyze mean nodule size.

Main Results:

• Included 11,963 patients across 18 studies.
• Mean nodule size increased by 0.52 mm annually overall (1990-2021).
• Diagnostic subgroup: mean nodule size increased by 0.57 mm annually.
• Screening subgroup: mean nodule size decreased by 0.23 mm annually until 2012.

Conclusions:

• Diagnostic ultrasonography shows increased thyroid nodule size, likely due to guideline changes.
• Screening studies indicate prevalent, easily identified subcentimeter nodules with questionable clinical relevance.
• Findings inform future thyroid nodule management guidelines and policies.