The patient's expectation during H2 breath testing: Don’t underestimate the reader's expectation
1
Digestive and Liver Disease 43 (2011) 86–87 Contents lists available at ScienceDirect Digestive and Liver Disease journal homepage: www.elsevier.com/locate/dld Correspondence The patient’s expectation during H 2 breath testing: Don’t under- estimate the reader’s expectation Sir, We read with interest the paper by Vernia et al. [1], suggest- ing 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 H 2 breath test results, a sub- group of patients, already tested for lactose malabsorption with lactose breath test, develop abdominal symptoms during a fur- ther breath test which foresees the administration of a solution containing 1 g of glucose, a dose unable to increase breath H 2 excre- tion. Three main criticisms must be raised. First, it is important to know whether the subgroup of patients showing such a symp- tomatic response after placebo was characterised by an increased prevalence or higher severity of anxiety, depression or somatisa- tion compared to the large group of subjects who did not show any symptoms. In a recent survey, the prevalence of somatisation disorder was diagnosed in 30% of patients with IBS and was associ- ated with significantly greater numbers of both gastrointestinal and non-gastrointestinal symptoms, but also with physician visits, tele- phone calls to physicians, urgent care visits and missed work days [2]. Consequently, an increased prevalence of psychiatric illness in this subgroup might also explain the acceptance of a further diag- nostic evaluation, making the selected group unreliable to draw the Authors’ conclusions. Second, the study did not follow a double- blind design, which is the only study design considered accurate for the aim of these studies. What we consider the major criticism to the paper is repre- sented by the protocol used for the lactose breath test: a 4-h lactose breath test was shown to be characterised by a very low sensi- tivity both in vivo [3] and in vitro [4]. A better sensitivity can be achieved by prolonging breath H 2 monitoring up to 6 (76%) or 7 h (81%) [3,4]. Accordingly, to perform an accurate evaluation of the relationship between symptom occurrence and lactose malabsorp- tion, the adoption of the most accurate protocol is mandatory. An inaccurate protocol cannot exactly separate lactose absorbers and lactose malabsorbers and, therefore, accurately define the relation- ship between intolerance symptom onset and both lactose and placebo/glucose intake. It could be argued that the protocol used by the Authors was rec- ommended by a recent survey on methodology of the H 2 breath test in gastrointestinal disorders [5]. However, we feel that the state- ments produced by this consensus conference on the diagnosis of lactose malabsorption are prone to several criticisms: the system- atic review of the literature performed by the section Authors was largely incomplete; papers were misquoted [3]; data evaluating in vivo [3] and in vitro [4] accuracy were not considered. Consequently, a mere quantitative, rather than qualitative, evaluation of papers on this topic was in fact performed. In conclusion, even if the nocebo effect may have a role during a lactose tolerance test, the paper by Vernia has methodological shortcomings. The Authors have been involved in H 2 breath test studies for a long time and an awareness of the pitfalls causing a low accuracy of this diagnostic tool is expected. Only an accurate test protocol could offer important insight on this topic and we expected such a protocol from these Authors. We think that while the patient’s expectation is a very important point, the reader’s expectation should also be considered! References [1] Vernia P, Di Camillo M, Foglietta T, et al. Diagnosis of lactose intolerance and the “nocebo” effect: the role of negative expectations. Dig Liver Dis 2010;43:86. [2] North CS, Downs D, Clouse RE, et al. The presentation of irritable bowel syn- drome in the context of somatization disorder. Clin Gastroenterol Hepatol 2004;2:787–95. [3] Di Stefano M, Missanelli A, Miceli E, et al. Hydrogen breath test in the diagnosis of lactose malabsorption: accuracy of new versus conventional criteria. J Lab Clin Med 2004;144:313–8. [4] Strocchi A, Corazza GR, Ellis J, et al. Detection of low doses of carbohydrate: accuracy of various breath H2 criteria. Gastroenterology 1993;105:1404–10. [5] Usai Satta P, Anania C, Astegiano M, et al. H2-breath testing for carbohydrate malabsorption. Aliment Pharmacol Ther 2009;29(Suppl. 1):14–8. Michele Di Stefano Gino Roberto Corazza ∗ 1st Department of Medicine, University of Pavia, IRCCS “S.Matteo” Hospital Foundation, Pavia, Italy ∗ Corresponding author. Tel.: +39 0382 502973; fax: +39 0382 502618. E-mail address: [email protected] (G.R. Corazza) doi:10.1016/j.dld.2010.06.003 Authors’ reply to “The patient’s expectations during H2 breath testing: Don’t underestimate the reader’s expectations!” 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 The letter had no sources of support. 1590-8658/$36.00 © 2010 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.
-
Upload
michele-di-stefano -
Category
Documents
-
view
215 -
download
2
Transcript of The patient's expectation during H2 breath testing: Don’t underestimate the reader's expectation
C
Te
S
iartaAiegltctttptadanp[tnAbf
sbta(rtilsp
oiml
1
Digestive and Liver Disease 43 (2011) 86–87
Contents lists available at ScienceDirect
Digestive and Liver Disease
journa l homepage: www.e lsev ier .com/ locate /d ld
[
[
[
[
[
We appreciate the interest generated by our study on the
orrespondence
he patient’s expectation during H2 breath testing: Don’t under-stimate the reader’s expectation
ir,
We read with interest the paper by Vernia et al. [1], suggest-ng that a “nocebo” effect due to lactose administration may cause
false positivity for lactose intolerance. As the Authors correctlyeported, it is known that the patient’s expectations may be linkedo a psycho-emotional mechanism inducing the onset of symptomsfter placebo or food and side effects after drug administration.nxiety, depression and somatisation were shown to have a role
n the pathophysiology of the nocebo effect. The paper by Verniat al. shows that, independently of H2 breath test results, a sub-roup of patients, already tested for lactose malabsorption withactose breath test, develop abdominal symptoms during a fur-her breath test which foresees the administration of a solutionontaining 1 g of glucose, a dose unable to increase breath H2 excre-ion. Three main criticisms must be raised. First, it is importanto know whether the subgroup of patients showing such a symp-omatic response after placebo was characterised by an increasedrevalence or higher severity of anxiety, depression or somatisa-ion compared to the large group of subjects who did not showny symptoms. In a recent survey, the prevalence of somatisationisorder was diagnosed in 30% of patients with IBS and was associ-ted with significantly greater numbers of both gastrointestinal andon-gastrointestinal symptoms, but also with physician visits, tele-hone calls to physicians, urgent care visits and missed work days2]. Consequently, an increased prevalence of psychiatric illness inhis subgroup might also explain the acceptance of a further diag-ostic evaluation, making the selected group unreliable to draw theuthors’ conclusions. Second, the study did not follow a double-lind design, which is the only study design considered accurateor the aim of these studies.
What we consider the major criticism to the paper is repre-ented by the protocol used for the lactose breath test: a 4-h lactosereath test was shown to be characterised by a very low sensi-ivity both in vivo [3] and in vitro [4]. A better sensitivity can bechieved by prolonging breath H2 monitoring up to 6 (76%) or 7 h81%) [3,4]. Accordingly, to perform an accurate evaluation of theelationship between symptom occurrence and lactose malabsorp-ion, the adoption of the most accurate protocol is mandatory. Annaccurate protocol cannot exactly separate lactose absorbers andactose malabsorbers and, therefore, accurately define the relation-hip between intolerance symptom onset and both lactose andlacebo/glucose intake.
It could be argued that the protocol used by the Authors was rec-mmended by a recent survey on methodology of the H2 breath testn gastrointestinal disorders [5]. However, we feel that the state-
ents produced by this consensus conference on the diagnosis ofactose malabsorption are prone to several criticisms: the system-
590-8658/$36.00 © 2010 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier
atic review of the literature performed by the section Authors waslargely incomplete; papers were misquoted [3]; data evaluating invivo [3] and in vitro [4] accuracy were not considered. Consequently,a mere quantitative, rather than qualitative, evaluation of papers onthis topic was in fact performed.
In conclusion, even if the nocebo effect may have a role duringa lactose tolerance test, the paper by Vernia has methodologicalshortcomings. The Authors have been involved in H2 breath teststudies for a long time and an awareness of the pitfalls causing alow accuracy of this diagnostic tool is expected. Only an accuratetest protocol could offer important insight on this topic and weexpected such a protocol from these Authors. We think that whilethe patient’s expectation is a very important point, the reader’sexpectation should also be considered!
References
1] Vernia P, Di Camillo M, Foglietta T, et al. Diagnosis of lactose intoleranceand the “nocebo” effect: the role of negative expectations. Dig Liver Dis2010;43:86.
2] North CS, Downs D, Clouse RE, et al. The presentation of irritable bowel syn-drome in the context of somatization disorder. Clin Gastroenterol Hepatol2004;2:787–95.
3] Di Stefano M, Missanelli A, Miceli E, et al. Hydrogen breath test in the diagnosisof lactose malabsorption: accuracy of new versus conventional criteria. J Lab ClinMed 2004;144:313–8.
4] Strocchi A, Corazza GR, Ellis J, et al. Detection of low doses of carbohydrate:accuracy of various breath H2 criteria. Gastroenterology 1993;105:1404–10.
5] Usai Satta P, Anania C, Astegiano M, et al. H2-breath testing for carbohydratemalabsorption. Aliment Pharmacol Ther 2009;29(Suppl. 1):14–8.
Michele Di StefanoGino Roberto Corazza ∗
1st Department of Medicine, University of Pavia,IRCCS “S.Matteo” Hospital Foundation, Pavia, Italy
∗ Corresponding author. Tel.: +39 0382 502973;fax: +39 0382 502618.
E-mail address: [email protected](G.R. Corazza)
doi:10.1016/j.dld.2010.06.003
Authors’ reply to “The patient’s expectations during H2 breathtesting: Don’t underestimate the reader’s expectations!”�
To the Editor,
“nocebo” effect in patients undergoing a lactose tolerance test[1]. Interpreting patients’ symptoms indeed has profound clinical
� The letter had no sources of support.
Ltd. All rights reserved.
