IBS clinical subtypes distribution differs depending on the population evaluated, the geographical location, and the criteria employed to define IBS and bowel habit subtypes. In most cases, clinical course is characterized by the presence of mild-to-moderate symptoms appearing sequentially. Prospective studies, using clear and stable diagnostic criteria and subtype definitions, and based on daily data collection should further characterize IBS clinical course.

CC appears to be a spectrum; most patients do not have abdominal pain/discomfort but others (with otherwise quite similar characteristics) are patients with IBS or are out of any established diagnosis.

The role ofHelicobacterpylori infection in the pathogenesis of functional dyspepsia is debated. It is known that a substantial fraction of dyspeptic patients manifest a low discomfort threshold to gastric distension. This study investigated the symptomatic pattern in 27 Hpylori positive and 23 H pylori negative patients with chronic functional dyspepsia, and potential relations between infection and gastric hyperalgesia. Specific symptoms (pain, nausea, vomiting, bloating/fullness, early satiety) were scored from 0 to 3 for severity and frequency (global symptom scores: 0-15). The mechanical and perceptive responses to gastric accommodation were evaluated with an electronic barostat that produced graded isobaric distensions from 0 to 20 mm Hg in 2 mm Hg steps up to 600 ml. Gastric compliance (volume/pressure relation) and perception (rating scale: 0-10) were quantified. Standard gastrointestinal manometry and recorded phasic pressure activity at eight separate sites during fasting and postprandially were also assessed. H pylon positive and H pylon negative patients manifested similar severity and frequency of specific symptoms and global symptom scores (mean (SEM)) (severity: 9'5 (2.0) v 9.0 (2.1); frequency: 10-8 (2.0) v 9*7 (2.2)). No differences were seen either in gastric compliance (53 (4)

The frequency of constipation and diarrhoea remains relatively stable over time. Changes in IBS subtypes are common, but changes between constipation and diarrhoea are rare. Alternating IBS is more frequent in women.