Discrepancies between upper GI symptoms described by those who have them and their identification by conventional medical terminology: a survey of sufferers in four countries.
Pairwise comparisons for the USA or UK versus Brazil or Russia were all highly significant ( P <0.0001).
also in 132,142 other papers
Quoted from the open-access full text in Europe PMC under the licence the publisher applied. The sentence is reproduced exactly as published; the emphasis is ours.