Thyroid Examination: Comparison between the Initial Screening and the Examination in Other Prefectures
When the Thyroid Examination commenced, many people were concerned about a relatively high percentage of examinees diagnosed as Grade A2. Therefore, in FY2012, the Ministry of the Environment (MOE) conducted the Thyroid Examination targeting approx. 4,300 children in Nagasaki, Yamanashi and Aomori Prefectures (3-prefecture examination) in the same manner as the examination conducted in Fukushima Prefecture.
The examination in Fukushima Prefecture covered children aged zero to 18, while the 3-prefecture examination excluded children aged under 3 and covered only those aged 3 to 18. As the cohort was much smaller in the 3-prefecture examination, a simple comparison cannot be made, but the results show that those diagnosed as Grade A2 were not greater in number among the children of Fukushima Prefecture. The figures above show that the percentage of those diagnosed as Grade A2 in Fukushima Prefecture was actually smaller by 9 points than in the three prefectures and, conversely, the percentage of those diagnosed as Grade A1 was larger by 9 points. The report of the 3-prefecture examination made the following observations: "It is generally known that the detection rate of nodular lesions is lower in the group of examinees aged 3 to 5 than in the group of examinees aged 6 or older, and that females show higher detection rate than males. Therefore, there is the possibility that a detection rate tabulated based on simple descriptive statistical methods as in this case may be higher than the actual rate."* The gaps in the percentages of those diagnosed as Grade A1 and Grade A2 between the examination in Fukushima Prefecture and the 3-prefecture examination are considered to be due to differences in the cohort sizes and examinees' ages (the 3-prefecture examination excluded children aged under 3).
* Source: "Report on the Outcome of the FY2012 Survey on Detection Rates of Thyroid Abnormalities" (commissioned by MOE), The Japan Association of Breast and Thyroid Sonology (March 2013)
- Included in this reference material on March 31, 2014
- Updated on December 1, 2017