The patient's expectation during H breath testing: Don't underestimate the reader's expectation.

摘要

We read with interest the paper by Vernia et al. [1], suggesting that a "nocebo" effect due to lactose administration may cause a false positivity for lactose intolerance. As the Authors correctly reported, it is known that the patient's expectations may be linked to a psycho-emotional mechanism inducing the onset of symptoms after placebo or food and side effects after drug administration. Anxiety, depression and somatisation were shown to have a role in the pathophysiology of the nocebo effect. The paper by Vernia et al. shows that, independently of H2 breath test results, a subgroup of patients, already tested for lactose malabsorption with lactose breath test, develop abdominal symptoms dursaing a further breath test which foresees the administration of a solution containing 1 g of glucose, a dose unable to increase breath H2 excretion. Three main criticisms must be raised. First, it is important to know whether the subgroup of patients showing such a symptomatic response after placebo was characterised by an increased prevalence or higher severity of anxiety, depression or somatisation compared to the large group of subjects who did not show any symptoms.