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HYPERSENSITIVITY TO DRUGS IS A FREQUENT EXTRA DIGESTIVE COMPLAINT IN IBS PATIENTS THAT IS NOT RELATED TO PSYCHOLOGICAL FACTORS

A Gougeon, M Binn, R Boileau, P Poitras
Hôpital Saint-Luc, Université de Montréal, Montreal, Quebec

Hypersensitivity to drugs is frequently reported by IBS patients in clinical practice but have not been well studied. We speculate that hypersensitivity to drugs constitutes an extra GI manifestation of the disease that could be explained by psychological factors like somatisation or amplification.
AIM: To compare the prevalence of hypersensitivity to drugs between people with or without IBS and the incidence of adverse events in these groups on placebo.
METHOD: Questionnaires were mailed to patients with IBS followed in our tertiary care clinic and to a control group. 71 and 67 women respectively completed the survey. We also performed a meta-analysis to verify the side effects profile of patients in the placebo arm of drugs trials using the data of the "Compendium of Pharmaceuticals and Specialties" published in 2003 by the Canadian Association of Pharmacists. We compared 1305 IBS patients to patients with diseases of similar evolution and severity: arthritis (n = 2647), hyperlipemia (n = 15377), peptic disorders (n = 786), asthma (n = 3212), osteoporosis (n = 5301), hypertension (n = 5295), psychiatric disorders (n = 8661).
RESULTS: Hypersensitivity to drugs was reported by 41% of IBS patients, but only by 8% of the control group (OR = 8.6; p < 0.001). This OR is similar to that of other well known extra GI complaints in IBS like fibromyalgia (OR = 5.9), back pain (OR = 4.6) or headache (OR = 2.4). Hypersensitivity to drugs was strongly associated with fatigue (p < 0.001), but not with psychological comorbidities such as anxiety (p > 0.1), depression (p > 0.4) or humor instability (p > 0.7). 30 side effects were evaluated in our meta-analysis of 42584 patients. The following were reported significantly more often by IBS patients: abdominal pain [10.5% (upper limit of normal in control group: 4.2%], bloating [4.8% (0.8%)], back pain [4.1% (3.1%)], vomiting [2.7% (2.5%)], neuralgia [1.3% (1.2%)] and dysmenorrhea [1.1% (0.7%)]. All these symptoms can be explained by the digestive or extra GI features of IBS.
CONCLUSION: Hypersensitivity to drugs is a frequent complaint in IBS patients and it should be added to the list of extra GI manifestations. This feature is not due to psychological factors. Biological factors, such as altered drug biodisponibility or enhanced receptor response, should be considered.

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