Supplementary Material for: Sex-Dependent Association between Weight Change and Thyroid Dysfunction: Population-Level Analysis Using the Korean National Health and Nutrition Examination Survey

<b><i>Background:</i></b> Although body weight change (BWC) is a common manifestation of thyroid dysfunction, solid evidence for whether to perform or on whom to perform thyroid function test in subjects complaining of BWC is lacking. <b><i>Objective:</i></b> To evaluate the association between thyroid dysfunction and BWC using a nationwide survey. <b><i>Method:</i></b> Data was obtained from the Korea National Health and Nutrition Examination Survey VI 2013–2015 and 5,456 subjects without previous thyroid disease were included. Serum thyroid-stimulating hormone (TSH), free T4, and self-reported BWC during the previous year were used for the evaluation. Weight loss or gain was defined as weight change of at least 3 kg. <b><i>Results:</i></b> In total, 1,017 men (37.3%) and 1,175 women (43.0%) reported BWCs during the previous year. The overall weighted prevalence of thyroid dysfunction was not significantly associated with the extent of BWC in men (<i>p</i> = 0.705) or women (<i>p</i> = 0.094). However, when the impact of TSH levels on weight change was separately evaluated for weight gain and loss after adjusting for age and body mass index in each sex, weight loss in women was significantly associated with TSH levels (hazard ratio 0.64, 95% CI 0.47–0.85, <i>p</i> = 0.03). No association of thyroid dysfunction was observed for weight gain in women (<i>p</i> = 0.23) or any changes in men (<i>p</i> = 0.875 in weight gain, <i>p</i> = 0.923 in weight loss). <b><i>Conclusions:</i></b> This study highlights the necessity of performing thyroid function testing in women who complain of weight loss, but such testing may be less vital in women with weight gain or men with any changes in weight.

<b><i>背景：</i></b> 尽管体重变化（body weight change, BWC）是甲状腺功能异常的常见临床表现，但针对主诉体重变化的人群，究竟是否应当开展甲状腺功能检测、又应针对哪些人群开展此类检测，目前仍缺乏确凿证据。<b><i>目的：</i></b> 基于一项全国性调查，评估甲状腺功能异常与体重变化之间的关联。<b><i>方法：</i></b> 研究数据取自2013-2015年韩国国民健康与营养调查第六轮（Korea National Health and Nutrition Examination Survey VI），最终纳入5456名既往无甲状腺疾病史的受试者。检测指标包括血清促甲状腺激素（thyroid-stimulating hormone, TSH）、游离甲状腺素（free T4），并通过受试者自我报告收集其过去一年的体重变化情况。本研究将体重变化幅度≥3 kg定义为体重减轻或体重增加。<b><i>结果：</i></b> 总计有1017名男性（占比37.3%）与1175名女性（占比43.0%）报告过去一年存在体重变化。男性群体中，甲状腺功能异常的整体加权患病率与体重变化幅度无显著相关性（<i>p</i>=0.705）；女性群体同样未观察到显著关联（<i>p</i>=0.094）。然而，在按性别校正年龄与体质量指数（body mass index, BMI）后，分别评估促甲状腺激素水平对体重增加与体重减轻的影响时发现，女性的体重减轻与促甲状腺激素水平存在显著相关性（危险比0.64，95%置信区间0.47~0.85，<i>p</i>=0.03）。未观察到女性体重增加与甲状腺功能异常存在关联（<i>p</i>=0.23）；男性群体无论体重增加（<i>p</i>=0.875）还是体重减轻（<i>p</i>=0.923），均未发现与甲状腺功能异常存在相关性。<b><i>结论：</i></b> 本研究提示，对于主诉体重减轻的女性，开展甲状腺功能检测具有必要性；而对于体重增加的女性，或是存在任何体重变化的男性，此类检测的必要性相对较低。