As much I read about this particular study, in the group of the more spicy eaters, there where plenty of rural people and in the other group more urban people. So, this sounds to me, that there are different factors inside the study which are interconnected and the "evidence" could also be linked to some different factors, for example more healthy lifestyle of rural people (particular in China: I assume healthier air). In the article, I read, they even suspected, that more tea consume of the spicy group could also cause the positive effect.

So, every study should be taken with a grain of salt, particularly when the exact circumstances are not told.