Eamonn Quigley
Cork university Hospital in Ireland

There are two approaches to making a clinical diagnosis of IBS. The first is by
exclusion, which is expensive and involves several tests that will give normal
results. The second approach is based on symptoms alone.
 
If the patient is below age 50, has typical symptoms and without alarm
features-such as hematochezia, anemia, persistent fever, weight loss of more
than 10 lbs, chronic severe diarrhea, and family history of colon cancer-then a
diagnosis of IBS can almost certainly be made.
 
Furthermore, a review of tests done in patients with clinical features of IBS
and a study comparing the prevalence of organic diseases in IBS patients with
the general population do not support the performing of diagnostic tests in
IBS patients.
 
What happens with IBS over time? Over a 12-month period, about 50 percent
of IBS patients will remain symptom-positive. About 21 percent will develop
new symptoms and another 11 percent will lose their symptoms.
 
A systematic review of randomized, controlled trials of the traditional
pharmacologic agents for IBS found smooth-muscle relaxants beneficial for
abdominal pain and loperamide effective for reducing diarrhea (Ann Intern Med
2000;133:136~147).
 
Surprisingly, there isn룑t a lot of good data to support the use of bulking
agents. The studies on psychotropic agents were small and inconclusive. But
overall, I do feel that the tricyclic antidepressants are effective.
 
Psychological therapy, which includes hypnosis and psychotherapy, has been
shown to be effective in reducing pain and diarrhea. While the mode of action
is unclear, the best response is found in patients whose symptom onset is
linked to stressors and who have a `waxing-and-waning` symptom pattern.
 
The newer agents for IBS target serotonin. Alosetron, a 5-hydroxytryptamine
type 3 (5-HT3) antagonist, has been shown to be effective in females with
diarrhea-predominant IBS.
 
Tegaserod (ZelmacR, Novartis), a 5-HT4 partial agonist, is effective for
constipation-predominant IBS.
 
A recent study on tegaserod in the Asia-Pacific population showed that the
drug provided greater overall satisfactory relief compared with placebo. The
effect of tegaserod was observed as early as week 1 and maintained
throughout the 12-week treatment period (Gut 2003;52:671~676). Quigley
pointed out that tegaserod also showed a significant benefit in relieving
individual symptoms of abdominal pain and discomfort, bloating and
constipation compared with placebo. Drug was well tolerated with the only
significant side effect being diarrhea, which was to be expected from a
prokinetic agent.
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