关于RCT和回顾性研究合并的问题

文章返修，有4篇RCT和20篇回顾性研究，审稿人给我建议：In my opinion, the results of this study would be much more relevant if the Quantitative Analysis included ONLY the randomized trials. This would ameliorate the effects of including non-randomized trials in the results, and might strengthen the study, as it would reduce the impact suggest by the authors themselves in the limitations section. 其中最重要的是认为我将RCT和回顾性研究合并是不合适的，建议我只用这4篇RCT做定量分析。我查了很多文献确实发现有很多将RCT和回顾性研究合并，如果我只纳入这4篇RCT，有些观察指标文献数量就不够无法得出结论，其他20篇回顾性研究该怎么处理？希望有老师指点迷津！