Wu and colleagues performed a meta-analysis including 259 studies to examine the overall risk of contrast-induced nephropathy and the need for dialysis. The writing was excellent and the data presented may be useful for the scientific community; however, some concerns should be addressed: 1、The number of included participants should be listed in the manuscript. 2、The heterogeneity between included studies was high, which might be related to the various population characteristics. Although the authors performed subgroup analysis according to the study design, angiography procedure, administration route, and publication year, the baseline of chronic kidney disease was also contributed to the between-study heterogeneity. Can the authors provide the data about the subgroup analysis according to the baseline of chronic kidney disease? 3、The study included certain randomized controlled trials (RCTs). The quality assessment of RCTs should be assessed by Cochrane risk-of-bias tool. 4、The Newcastle–Ottawa-Quality Assessment Scale (NOS) included a total of eight items, but the authors only evaluated four of them. This method is not universal. Can the authors explain the reason to evaluate the study quality in this way? 5、Why did the authors perform the subgroup analysis according to the global distribution? The authors should discuss it in the discussion section. 6、Can the authors provide the interaction P value in the subgroup analysis? 7、In the clinical outcome, whether renal replacement therapy was temporary or long-term？ 8、This study still provided rich data in this field to guide clinical practice. It would be better to provide the data about the risk of contrast-associated nephropathy or the need for renal replacement therapy in high-risk patients.