1）最近在看关于非甾体类药物预防ERCP术后胰腺炎的文章，看到了"How to select patients and timing for rectal indomethacin to prevent post-ERCP pancreatitis（PEP） a systematic review and meta-analysis."这篇meta分析，它纳入了Patai 等在2015年的RCT“Effect of Rectal Indomethacin for Preventing Post-ERCP Pancreatitis Depends on Difficulties of Cannulation Results from a Randomized Study With Sequential Biliary Intubation ”。其中进行平均危险度和高危人群亚组分析时把Patai的RCT研究中的患者分成了高危组和平均危险度组，其中高危组共计393人，平均危险度组共计146人。我阅读了RCT文献原文，觉得这393人不能定义为高危组，剩余146人应当是低危组，而非平均危险度人群。可以请各位老师帮忙指点一下吗，是不是我的理解有误？
4）这个RCT样本量是539，文献中有这样一段描述A total of 393 patients (72.9% of all) had at least 1 deﬁnite patient-related risk factor for PEP deﬁned by Masci et al.41 Of these, PEP occurred in 32 cases (16.5%) in the placebo group and in 14 cases (7%) in the indomethacin group (P=0.004) (Fig. 3A), indicating a NNT of 12. In 179 patients (33.2%) with at least 1 deﬁnite procedurerelated risk factor,41 indomethacin was also eﬀective (28.3% vs. 13.8%, P=0.028) (Fig. 3B) indicating a NNT of 7. In patients without any deﬁnite risk factor for PEP, the occurrence of PEP was low (4.0%) and in this group the eﬀect of indomethacin could not be demonstrated (4.3% vs. 3.8%, P=1.0). In patients with at least 1 patient-related or procedure-related risk factor (representing 81.6% of all cases), PEP was relatively frequent (15.8%) and indomethacin was eﬀective (15.8 vs. 7.3%, P=0.007) (Fig. 3C) and the NNT was 12. In those patients with at least 1 patient-related risk factor plus at least 1 procedurerelated risk factor (24.5% of all cases), the frequency of PEP was extremely high and among these patients indomethacin diminished the rate of PEP from 35.2% to 14.8% (P=0.009) (Fig. 3D).