Table_1_Comparative Efficacy of 2 L Polyethylene Glycol Alone or With Ascorbic Acid vs. 4 L Polyethylene Glycol for Colonoscopy: A Systematic Review and Network Meta-Analysis of 12 Randomized Controlled Trials.pdf

Background: Colonoscopy remains an optimal approach for early detection and treatment of gastrointestinal lesions, however adequate bowel preparation is the critical contributor to effective and safe colonoscopy. Polyethylene glycol (PEG)-based bowel cleansing regime has been the first recommendation before colonoscopy, however it remains unknown which regime is the optimal option.
Aim: The aim of our study is to determine the comparative efficacy of 2 L PEG alone or plus ascorbic acid (Asc) vs. 4 L PEG alone for bowel cleansing prior to colonoscopy.
Methods: We assigned two independent investigators to search and screen potential records, extract essential information, and appraise the risk of bias of individual study accordingly. Then, we adopted RevMan 5.3, Stata 14.0, and WinBUGS 1.4 software to perform all statistical analyses. We also calculated the surface under the cumulative ranking curve (SCURA) in order to rank all regimes.
Results: Twelve studies involving 4,106 patients were analyzed finally. Pooled results indicated an improved bowel preparation efficacy in 2 L PEG plus ascorbic acid with split-dose regime rather than in 2 L PEG plus ascorbic acid (OR, 0.25; 95% CI, 0.18–0.36), 4 L PEG with split dose (OR, 3.18; 95% CI, 2.17–4.66), and 4 L PEG (OR, 4.53; 95% CI, 3.07–6.67) regimes, which was confirmed by network meta-analyses; a better compliance in 2 L PEG plus Asc with split dose (OR, 3.08; 95% CI, 1.51–6.30) and 4 L PEG with split dose (OR, 0.43; 95% CI, 0.22–0.82) regime rather than in 4 L PEG regime, but network meta-analyses generated inconsistency results; a higher preference in 2 L PEG plus Asc with split dose regime rather than in 4 L PEG split dose (OR, 2.24; 95% CI, 1.02–4.90), which were not supported by network meta-analyses; no statistically significant difference when all regimes compared with each other in terms of adverse events.
Conclusions: As for bowel preparation before colonoscopy, 2 L PEG ascorbic acid with split dose should be optimally prescribed. Further studies investigating the comparative efficacy of 2 L PEG related to 4 L PEG, 4 L PEG with split dose, and 2 L PEG plus ascorbic acid with split dose, respectively are needed.

背景：结肠镜检查仍是胃肠道病变早期筛查与诊疗的最优手段，但充分的肠道准备是保障结肠镜检查安全、有效的关键因素。以聚乙二醇（Polyethylene glycol，PEG）为基础的肠道清洁方案是结肠镜检查前的首推方案，但目前尚无定论何种方案为最优选择。
目的：本研究旨在比较单用2L聚乙二醇（Polyethylene glycol，PEG）、联用抗坏血酸（ascorbic acid，Asc）的PEG方案，与单用4L PEG方案在结肠镜检查前肠道清洁中的疗效差异。
方法：由两名独立研究者分别开展文献检索、筛选工作，提取核心研究信息，并逐一评价各项研究的偏倚风险。随后采用RevMan 5.3、Stata 14.0及WinBUGS 1.4软件完成所有统计分析，同时计算累积排序曲线下面积（surface under the cumulative ranking curve，SCURA）以对各肠道准备方案进行排序。
结果：最终共纳入12项研究，涉及4106例患者。合并分析结果显示，采用分次给药方案的2L PEG联用抗坏血酸方案的肠道清洁疗效优于单用2L PEG联用抗坏血酸（比值比OR=0.25，95%置信区间CI：0.18~0.36）、单用4L PEG分次给药方案（OR=3.18，95%CI：2.17~4.66）及单用4L PEG方案（OR=4.53，95%CI：3.07~6.67），该结论经网络Meta分析验证；采用分次给药方案的2L PEG联用抗坏血酸方案及4L PEG分次给药方案的患者依从性优于单用4L PEG方案（OR=3.08，95%CI：1.51~6.30；OR=0.43，95%CI：0.22~0.82），但网络Meta分析结果未支持该差异；采用分次给药方案的2L PEG联用抗坏血酸方案的患者接受度优于4L PEG分次给药方案（OR=2.24，95%CI：1.02~4.90），但该结论未得到网络Meta分析支持；各方案间不良事件发生率的差异无统计学意义。
结论：对于结肠镜检查前的肠道准备，分次给药方案的2L PEG联用抗坏血酸应为首选推荐方案。未来仍需开展进一步研究，分别比较2L PEG、4L PEG、4L PEG分次给药方案及分次给药方案的2L PEG联用抗坏血酸之间的疗效差异。