Supplementary Material for: High Serum Ferritin Levels Increase the Risk of Hyperuricemia: A Cross-Sectional and Longitudinal Study

Background/Aims: To examine the cross-sectional and longitudinal associations of serum ferritin levels with hyperuricemia. Methods: A cross-sectional and subsequently prospective study was performed among the employees of Zhenhai Refining and Chemical Company, Ningbo, China. In a cross-sectional study, the association between serum ferritin levels and the prevalence of hyperuricemia was analyzed. Subjects who were free of hyperuricemia at baseline were followed up annually to explore the prospective association between serum ferritin levels and hyperuricemia incidence. Results: Of the 10,074 subjects enrolled at baseline, 1,731 (17.18%) fulfilled the diagnostic criteria of hyperuricemia. Subjects with hyperuricemia presented significantly higher serum ferritin levels, and the levels were positively correlated with the prevalence of hyperuricemia. During a total of 22,367 person-years of follow-up, 502 subjects developed hyperuricemia. The overall incidence of hyperuricemia for 1,000 person-years of follow-up was 22.4, ranging from 17.6 in subjects with baseline serum ferritin levels in the first quintile to 19.2, 21.7, 23.9, and 30.7 in subjects in quintiles 2, 3, 4, and 5, respectively (p for trend < 0.001). Cox regression analyses showed that serum ferritin levels were positively associated with the risk of incident hyperuricemia. Conclusions: Our cross-sectional and longitudinal results indicate that high serum ferritin levels increase the risk of hyperuricemia.

研究背景与目的：探讨血清铁蛋白水平与高尿酸血症的横断面及纵向关联。方法：本研究以中国宁波镇海炼化公司员工为研究对象，开展横断面及后续前瞻性队列研究。在横断面研究中，分析血清铁蛋白水平与高尿酸血症患病率的关联；对基线时未患高尿酸血症的研究对象进行年度随访，以探究血清铁蛋白水平与高尿酸血症发病的前瞻性关联。结果：基线时纳入的10074名研究对象中，1731人（17.18%）符合高尿酸血症诊断标准。高尿酸血症患者的血清铁蛋白水平显著更高，且该水平与高尿酸血症患病率呈正相关。在总计22367人-年的随访期间，共有502名研究对象新发高尿酸血症。每1000人-年随访的高尿酸血症总体发病率为22.4，基线血清铁蛋白水平处于第一五分位组的研究对象发病率为17.6，第二、第三、第四、第五五分位组分别为19.2、21.7、23.9和30.7（趋势检验p<0.001）。Cox回归分析显示，血清铁蛋白水平与高尿酸血症发病风险呈正相关。结论：本研究的横断面及纵向结果表明，高水平血清铁蛋白会升高高尿酸血症的发病风险。