Even where results indicated there was evidence of a difference, the reviewers found no sign that these differences would have any noticeable effect on health.

【翻译】尽管结果表明存在着有差异的证据，但审查员并未发现这些差异会对健康有明显影响的迹象。

where 是连词，原本引导地点状语从句，有时可以引导让步从句。放在主句前意为“尽管”，放在主句后意为“然而；但是”，跟whereas 和while 的用法一相同。even只是用来强调而已。

《柯林斯词典》：

CONJ-SUBORD (用于引导从句进行对比) 然而

You use where to introduce a clause that contrasts with the other parts of the sentence.

Where some people learned to play the accordion for dances in their community, others took music lessons.

一些人学习弹手风琴，为他们社区里的舞蹈表演进行伴奏，而其他人则上音乐课。

Sometimes a teacher will be listened to, where a parent might not. 

有时教师的话会听，而父母的话可能就不听。