Future aspects of functional gastrointestinal disease: how should treatments be evaluated.

Evaluation can only be approached when groups to receive any form of therapy are well defined. To make progress in an area now confused, the best strategy would seem to involve separating from the mass of FGD patients, sub-groups which are well defined by tight diagnostic criteria, and initially limiting all research, including clinical trials, to such groups. Overlapping syndromes can be studied later. Clearly defined psychiatric illnesses should be diagnosed by DSM criteria and excluded from study. While research and long-term clinical trials should be limited to tightly defined groups, short-term responses to specific therapies could be used to define the groups, following which clinical clusters for that group could be re-evaluated. In broad terms, across-the-board attention to visceral sensitivity, nervous function and psychosocial factors seem more likely to yield insights in IBS than in NUD, but at present no confident statements can be made about pathogenesis in either group. Further clinical trials performed as in the past, are largely inappropriate at this time.