Difference in rates is prima facie evidence of bias, due to the disagreement. If someone says A and someone else says not-A, you don't need to know what A actually is to observe the contradiction and know at least one party is wrong.

Unless A contains indexicals that point to different things in the two cases.

(Maybe Asian acupunturists are better than European ones, or maybe East Asians respond better to acupuncture than Caucasians for some reason, or...)

( I'm not saying that this is likely, just that it's possible.)