Authors’ reply to “The patient's expectations during H2 breath testing: Don’t underestimate the reader's expectations!”☆
Article Outline
To the Editor,
We appreciate the interest generated by our study on the “nocebo” effect in patients undergoing a lactose tolerance test [1]. Interpreting patients’ symptoms indeed has profound clinical implications, and may lead to inappropriate restriction of the main source of dietary calcium. The letter of Drs Corazza and Di Stefano, however, criticizes the reliability of results and casts doubts on the conclusions of our paper.
The first point raised in the letter [2] is that anxiety, depression and somatisation were not investigated. It is thus suggested that “an increased prevalence of psychiatric illness in the study makes the selected group unreliable to draw conclusions”. It is hard to concur that high anxiety, depression and somatisation scores define the existence of psychiatric illness. Moreover, our study, for the first time in our knowledge, specifically documented the presence, and the clinical implications, of negative expectations (nocebo effect) in patients reporting symptoms during negative lactose tolerance tests. The mechanisms underlying the nocebo effect were not aims of the study and deserve further investigation.
The second point suggests the need for a double blind design of the study. As reported in the material and method section, before administering the sugar load, all patients were required to report the occurrence of any symptom, as usual during any hydrogen breath test. The personnel merely recorded the patients’ reports, if any. The finding that a considerable proportion lactose-malabsorbers in the control group also experienced symptoms (opposite to what was anticipated) makes an active intervention of the involved personnel unlikely.
The crucial point of the letter relates specifically to the procedure, which has been considered “inaccurate” and the protocol consequently “burdened by methodological shortcomings”. This contention is incorrect. Instead of the standard 4-h protocol, used in this and almost all other published studies as well as in clinical practice, Drs Corazza and Di Stefano insist that the 6–7
h test proposed by their group [3] should be considered the only acceptable one. The Rome Consensus Conference [4], they so strongly criticize, adhered to the recommendations of the National Programme for Guidelines and the articles reviewed were scored according to internationally accepted models. The Consensus Conference recommended the 4-h test (level of evidence 1, strength of recommendation A), whereas the 6–7h test was considered only as a possible alternative with less scientific evidence (LE IIb, SR B) [4].
It is not unusual that valuable and experienced scientists, as Dr Corazza and Dr Di Stefano indeed are, are so deeply convinced by their own view to disregard or criticize conflicting evidence. Surprisingly enough, in the present case, the same Dr Corazza and Dr Di Stefano were actively involved in the Rome Consensus Conference (as promoter and co-author of the final statements [4], and as a member of two working teams, respectively) and they used the same “unreliable” 4-h protocol in a recently published paper [5].
In one regard we completely agree with Dr Corazza and Dr Di Stefano, i.e. that “the reader's expectations should also be considered”.
References
- Diagnosis of lactose intolerance and the “nocebo effect”: the role of negative expectations. Dig Liver Dis. 2010;42:616–619
- . The patient's expectation during H2 breath testing: don’t underestimate the reader's expectation. Dig Liver Dis. 2011;43:86
- Detection of low doses of carbohydrate: accuracy of various breath H2 criteria. Gastroenterology. 1993;105:1404–1410
- Methodology and indications of H2 breath testing in gastrointestinal diseases: the Rome Consensus Conference. Aliment Pharmacol Ther. 2009;29(Suppl. 1):1–49
- Lactose malabsorption and intolerance in the elderly. Scand J Gastroenterol. 2001;36:1274–1278
☆ The letter had no sources of support.
PII: S1590-8658(10)00317-8
doi:10.1016/j.dld.2010.09.008
© 2010 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Inc All rights reserved.
