Saliva as a tool for monitoring hemodialysis: a systematic review and meta-analysis

Abstract This study aimed to assess whether the reductions in serum urea and creatinine levels are different from the reductions in salivary urea and creatinine levels that occur after hemodialysis in chronic renal patients. The systematic review protocol was registered in the PROSPERO database. Eight databases were searched to identify pretest-posttest studies of chronic kidney disease patients undergoing hemodialysis, with no language or year restrictions. The JBI Critical Appraisal Tool was used to assess the risk of bias. Meta-analyses using random-effect models were conducted to compare salivary and serum correlations and to pooled mean and proportion differences from pre- to posthemodialysis urea and creatinine levels by subgroup analysis. The I2 test was used to assess heterogeneity, and a meta-regression was performed to statistically assess correlations and differences in the pooled effects pre- and postdialysis. The Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) was used to assess the certainty of evidence. The search resulted in 1404 records, and only six studies (n = 252 participants) fulfilled the eligibility criteria and were included. The studies were published between 2013 and 2018. All studies showed a significant reduction in both salivary and serum urea/creatinine levels. All eligible studies presented a low risk of bias. The meta-analysis shows a moderate to high correlation between salivary and blood levels of urea (r: 0.79; 95% CI: 0.56-1.00) and creatinine (r: 0.64; 95%CI: 0.16–1.00), with a very low level of certainty. The reductions in salivary urea and creatinine levels are similar to and correlated with the reductions in blood urea and creatine levels after hemodialysis among chronic kidney disease patients.

摘要 本研究旨在评估慢性肾病患者接受血液透析（hemodialysis）后，血清尿素与肌酐水平的下降幅度是否与唾液尿素、肌酐水平的下降幅度存在差异。本系统评价方案已在PROSPERO数据库注册。本研究检索了8个数据库，以筛选针对接受血液透析的慢性肾病患者的试验前后研究，未设置语言与年份限制。采用JBI关键评价工具（JBI Critical Appraisal Tool）评估偏倚风险。通过随机效应模型开展荟萃分析，对比唾液与血清样本的相关系数，并通过亚组分析合并血液透析前后尿素与肌酐水平的均数差与率差。采用I²检验评估异质性，并通过元回归对透析前后合并效应量的相关性与差异进行统计学分析。采用推荐分级、评估、制定与评价系统（Grading of Recommendation, Assessment, Development, and Evaluation, GRADE）评估证据确定性。本次检索共获得1404条记录，仅6项研究（共252名受试者）符合纳入标准并被纳入分析。相关研究发表于2013年至2018年期间。所有研究均显示唾液与血清尿素/肌酐水平均出现显著下降，且均存在较低的偏倚风险。荟萃分析结果显示，唾液与血液尿素（r=0.79；95%CI：0.56~1.00）、肌酐（r=0.64；95%CI：0.16~1.00）水平呈中高度相关，但证据确定性极低。慢性肾病患者血液透析后，唾液尿素与肌酐水平的下降幅度与血液尿素、肌酐水平的下降幅度相似且呈显著相关。