Supplementary Material for: Aging Promotes Progression of IgA Nephropathy: A Systematic Review and Meta-Analysis

<b><i>Background:</i></b> There has been considerable interest in whether old age is associated with IgA nephropathy (IgAN) progression, which is still controversial. <b><i>Methods:</i></b> We searched multiple databases for studies published from 1980 to 2012. The inclusion criteria were case-control, cohort studies published in any language. The included studies needed to have an older group. IgAN was proven by biopsy. <b><i>Results: </i></b>We included 9 studies with a total of 6,543 patients. The meta-analyses of other risk factors between the older group (&gt;50 years old) and the non-older group (15-50 years old) found significant differences in the presence of hypertension, proteinuria, serum cholesterol levels and baseline renal function. In the overall analysis, compared to the non-older group, older age significantly increased the incidence of developing end-stage renal disease [ESRD; relative risk (RR) random model 1.95; 95% CI: 1.27-3.01]. In the subgroup analyses, we found the age limit and traditional risk factors of IgAN may be the sources of heterogeneity between studies. Moreover, the RR (2.56) of the Asian countries was much higher than the RR (1.11) of the European countries. <b><i>Conclusions:</i></b> This comprehensive review revealed that old age is a real risk factor for IgAN progression to ESRD. The incidence of ESRD in the older IgAN patients was 1.95 times higher than that in the non-older IgAN patients. Moreover, the risk of IgAN progression to ESRD of the older patients in Asia was higher than that of the older patients in Europe.

**背景**：已有诸多研究探讨老年与IgA肾病（IgA nephropathy, IgAN）的进展相关性，但该议题迄今仍存在争议。
**方法**：我们检索了1980年至2012年发表于多个数据库的相关研究。纳入标准为不限发表语言的病例对照研究、队列研究，且纳入研究需包含老年组。所有受试者的IgAN均经肾活检确诊。
**结果**：本研究共纳入9项研究，合计6543例患者。针对老年组（年龄＞50岁）与非老年组（年龄15~50岁）间其他危险因素的荟萃分析显示，两组在高血压发生率、蛋白尿水平、血清胆固醇水平及基线肾功能方面存在显著差异。整体分析表明，与非老年组相比，老年显著增加终末期肾病（end-stage renal disease, ESRD）的发生风险[相对危险度（relative risk, RR）随机效应模型：1.95；95%置信区间（confidence interval, CI）：1.27~3.01]。亚组分析显示，年龄界值及IgAN传统危险因素可能是各研究间异质性的来源。此外，亚洲国家的RR值（2.56）远高于欧洲国家的RR值（1.11）。
**结论**：本综合综述证实，老年是IgAN进展至终末期肾病的明确危险因素。老年IgAN患者发生终末期肾病的风险是非老年患者的1.95倍。此外，亚洲老年IgAN患者进展至终末期肾病的风险高于欧洲老年患者。