Tea is a popular beverage around the world and has properties that can affect the immune system. The association between tea consumption and the risk of rheumatoid arthritis (RA), a chronic autoimmune disease primarily affecting the joints, is not well studied and results are conflicting. We collected data on tea consumption for 2237 incident RA cases diagnosed 2005–2018 and 4661 controls matched on age, sex, and residential area. Tea consumption was classified into no (0 cups/day), irregular (< 1 cup/day), regular (1–2 cups/day), and high (≥ 2 cups/day) consumption, and irregular consumption was used as the reference category. Missing data on tea consumption was classified as no consumers, and sensitivity analyses were performed to test this assumption. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression, adjusting for smoking, coffee, alcohol, educational level, and body mass index. We also performed stratified analysis on sex, anti-citrullinated autoantibody (ACPA) status, and smoking habits. Among the cases, we found 57.3% to be ever consumers of tea with 19.7 having a high tea consumption. Corresponding figures for the controls were 58.4% ever drinkers with 22.1% high tea consumers. High tea consumption had an inverse association to the risk of RA compared to irregular consumption [OR = 0.78 (95% CI 0.66–0.92)], but the association lost statistical significance in the adjusted model [adjusted OR (adjOR) = 0.85 (95% CI 0.71–1.01)]. Among non-tea consumers, a protective effect was also observed compared to irregular consumers [adjOR = 0.82 (95% CI 0.70–0.88)], but this association did not withstand sensitivity analysis, possibly due to bias. In the ACPA-positive group and among current smokers, a protective effect of tea consumption was observed among the high tea consumers [adjOR = 0.76 (95% CI 0.62–0.94) and adjOR = 0.60 (95% CI 0.38–0.95), respectively]. This study suggests a protective effect of high consumption of tea, among smokers and for ACPA-positive RA. Not applicable

中文翻译：

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喝茶与降低类风湿性关节炎的风险有关吗？瑞典病例对照研究

茶是世界各地流行的饮料，具有影响免疫系统的特性。茶消费与类风湿性关节炎 (RA) 风险之间的关联尚未得到充分研究，类风湿性关节炎 (RA) 是一种主要影响关节的慢性自身免疫性疾病，结果相互矛盾。我们收集了 2005-2018 年诊断的 2237 例 RA 病例和 4661 例年龄、性别和居住区匹配的对照的茶叶消费数据。茶消费分为无（0杯/天）、不规律（< 1杯/天）、规律（1-2杯/天）和高（≥2杯/天）消费，不规律消费被用作参考类别。茶叶消费数据的缺失被归类为没有消费者，并进行了敏感性分析来检验这一假设。优势比 (OR) 和 95% 置信区间 (CI) 使用条件逻辑回归计算，调整吸烟、咖啡、酒精、教育水平和体重指数。我们还对性别、抗瓜氨酸自身抗体 (ACPA) 状态和吸烟习惯进行了分层分析。在这些案例中，我们发现 57.3% 的人曾经是茶的消费者，其中 19.7% 的人经常喝茶。对照组的相应数字是 58.4% 的人饮酒，22.1% 的人喝下午茶。与不规律消费相比，喝茶与 RA 风险呈负相关 [OR = 0.78 (95% CI 0.66–0.92)]，但该关联在调整后的模型中失去了统计显着性 [调整后的 OR (adjOR) = 0.85 (95 % CI 0.71–1.01)]。在非茶消费者中，与不规律的消费者相比，也观察到了保护作用 [adjOR = 0。82 (95% CI 0.70–0.88)]，但这种关联经不起敏感性分析，可能是由于偏倚。在 ACPA 阳性组和当前吸烟者中，喝茶对喝茶有保护作用 [adjOR = 0.76 (95% CI 0.62–0.94) 和 adjOR = 0.60 (95% CI 0.38–0.95)，分别]。这项研究表明，大量饮用茶对吸烟者和 ACPA 阳性 RA 有保护作用。不适用 吸烟者和 ACPA 阳性 RA。不适用 吸烟者和 ACPA 阳性 RA。不适用