As to the limitations of the study potential confounders cannot be taken into account e.g. differences in iodine status between regions.
(65.8% [95%CI: 63.8; 67.8]) and a lower proportion in the Walloon Region (60.6% [95%CI: 59.6; 61.7]). As to the limitations of the study potential confounders cannot be taken into account e.g. differences in iodine status between regions.