Critique article analysis -- A Randomized Control Study

DOI: 10.1542/peds.2010-0467 2010;126;e1445-e1452; originally published online Nov 15, 2010; Pediatrics

Lucia Peccarisi, Flavia Indrio and Luciano Cavallo Bucci, Francesca Gagliardi, Elena Lionetti, Stefania Castellaneta, Lorenzo Polimeno, Ruggiero Francavilla, Vito Miniello, Anna Maria Magistà, Angela De Canio, Nunzia

Functional Abdominal Pain GG in Children WithLactobacillusA Randomized Controlled Trial of

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rights reserved. Print ISSN: 0031-4005. Online ISSN: 1098-4275. Grove Village, Illinois, 60007. Copyright © 2010 by the American Academy of Pediatrics. All and trademarked by the American Academy of Pediatrics, 141 Northwest Point Boulevard, Elk publication, it has been published continuously since 1948. PEDIATRICS is owned, published, PEDIATRICS is the official journal of the American Academy of Pediatrics. A monthly

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ARandomizedControlled Trial of LactobacillusGG in ChildrenWith Functional Abdominal Pain

WHAT’SKNOWNONTHISSUBJECT: Chronic abdominal pain is one of themost common reasons for referral to a specialist. Effectivemeasures for the treatment of recurrent abdominal pain are lacking. Data on theuse of probiotics in adultswith irritable bowel syndrome (IBS) have demonstrated their efficacy.

WHAT THISSTUDYADDS: Lactobacillus rhamnosus strain GG (LGG) is effective for reducing the frequency and severity of pain in childrenwith IBS. The beneficial effect of LGGpersists beyond the cessation of the administration and represents a valid therapeutic option. Small intestinal permeability is significantly increased in childrenwith IBS.

abstract + OBJECTIVE: OuraimwastodeterminewhetherLactobacillusrhamno- susGG (LGG) relieves symptoms in childrenwith recurrent abdominal pain.

PATIENTS ANDMETHODS: A total of 141 childrenwith irritable bowel syndrome(IBS)orfunctionalpainwereenrolledin9primarycaresites and a referral center. Children entered a randomized, double-blind, placebo-controlled trial and received LGG or placebo for 8weeks and enteredfollow-upfor8weeks.Theprimaryoutcomewasoverallpainat the end of the intervention period. At entry and at the end of the trial, childrenunderwent a double-sugar intestinal permeability test.

RESULTS: Compared with baseline, LGG, but not placebo, caused a significantreductionofboth frequency(P� .01)andseverity (P� .01) ofabdominalpain. Thesedifferencesstillweresignificantat theendof follow-up (P � .02 and P � .001, respectively). At week 12, treatment successwasachievedin48childrenintheLGGgroupcomparedwith37 children in the placebo group (P � .03); this difference still was present at the endof follow-up (P � .03). At entry, 59%of the children hadabnormalresultsfromtheintestinalpermeability test;LGG,butnot placebo, determined a significant decrease in the number of patients with abnormal results from the intestinal permeability testing (P � .03). These effectsmainlywere in childrenwith IBS.

CONCLUSIONS: LGGsignificantlyreducesthefrequencyandseverityof abdominalpain inchildrenwith IBS; thiseffect issustainedandmaybe secondary to improvement of the gut barrier. Pediatrics 2010;126: e1445–e1452

AUTHORS: Ruggiero Francavilla,MD, PhD,a VitoMiniello, MD,a AnnaMariaMagistà,MD,a AngelaDeCanio,MD,a

Nunzia Bucci,MD,a FrancescaGagliardi, PhD,a Elena Lionetti,MD,b Stefania Castellaneta,MD,c Lorenzo Polimeno, PhD,d Lucia Peccarisi,MD,e Flavia Indrio,MD,a

and LucianoCavallo,MDa

Departments of aDevelopmental Biomedicine and dEmergency andOrgan Transplantation, Gastroenterology Section, University of Bari, Bari, Italy; bDepartment of Pediatrics, University of Catania, Catania, Italy; cDepartment of Pediatrics, SanPaolo Hospital, Bari, Italy; and eASL-Bari, Bari, Italy

KEYWORDS abdominal pain, intestinal barrier function, pediatric gastroenterology, probiotics, Lactobacillus rhamnosusGG

ABBREVIATIONS RAP—recurrent abdominal pain IBS—irritable bowel syndrome FAP—functional abdominal pain LGG—Lactobacillus rhamnosus strain GG VAS—visual analog scale FPS—FacesPain Scale IPT—intestinal permeability test La/Ma—lactulose-to-mannitol ratio

This trial has been registered atwww.clinicaltrials.gov (identifierNCT00876291).

www.pediatrics.org/cgi/doi/10.1542/peds.2010-0467

doi:10.1542/peds.2010-0467

Accepted for publication Aug 26, 2010

Address correspondence toRuggiero Francavilla,MD, PhD, Clinica Pediatrica “B. Trambusti,” Piazza Giulio Cesare, 11-Policlinico, Bari, Italy. E-mail: [email protected]

PEDIATRICS (ISSNNumbers: Print, 0031-4005; Online, 1098-4275).

Copyright©2010by the American Academyof Pediatrics

FINANCIALDISCLOSURE: The authors have indicated they have nofinancial relationships relevant to this article to disclose.

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Recurrent abdominal pain (RAP) pri- marily is a functional disorder that af- fects 10% to 15% of school-aged chil- dren and is one of the most common reasons for referral to a pediatric gastroenterologist.1,2

Authors of the pediatric Rome crite- ria,3 inanattempt to improve theman- agement of children with RAP, have proposed4diagnosticsymptom-based categories: irritable bowel syndrome (IBS); functional dyspepsia; childhood functional abdominal pain (FAP); and abdominal migraine. Conventional in- terventions include reassurance and general advice about managing pain. Although this level of intervention has beenassociatedwith clinical improve- ment,4 medication and psychological therapies alsomaybenecessary. Only a few small randomized clinical trials have been conducted on childrenwith abdominalpain,and their resultshave shown inconclusive evidenceof the ef- ficacy of these treatments.5 The au- thors of 2 recent Cochrane systematic reviews6,7 have concluded that there is weak evidence for the benefit of medication and/or dietary manipula- tion in children with RAP and called for larger randomized clinical trials. A recent multicenter, randomized, placebo-controlled trial8 revealed that amitriptyline was as effective as pla- cebo in the treatment of childrenwith functional gastrointestinal disorder, thusreinforcingtheneedforexploring different therapeutic options.

Probiotics are “live microorganisms which, when consumed in adequate amounts, confer a health benefit on the host.”9 Clinical applications of probiotics include treatment or pre- vention of different gastrointestinal disorders.10,11 Possiblemechanismsof actioninclude(1)bindingtosmall-and large-bowel epithelium and produc- tion of substances that may inhibit pathogenic organisms,12 (2) modulat- ing the gastrointestinal lumen toward

an anti-inflammatory state,13 and (3) converting undigested carbohydrates into short-chain fatty acids, improving gut function.

One of the best-studied probiotic bac- teria in clinical trials for treating and/or preventing several intestinal disorders is Lactobacillus rhamnosus strain GG (LGG).14 This probiotic has been tested in childrenwith intestinal functional disorders; results have been inconclusive.15,16 Effective mea- sures for the treatment of RAP are lacking, and given the disorder’s high prevalence, the need for an appropri- ate treatment is critical. Data on the possible use of probiotics in adults with IBS have indicated their efficacy; however, given the limitations of the existing data in children, we per- formed a randomized, double-blind, placebo-controlled trial to establish whether LGG relieves symptoms in childrenwith IBS or FAP.

PATIENTS ANDMETHODS

A randomized, double-blind, placebo- controlled, parallel-group trialwas con- ducted in southern Italy between 2004 and2008.Thestudywasplannedaccord- ingtotherecommendationsestablished bytheconsensusreportonclinicaltrials in IBS.17 The institutionalreviewboardof theUniversityofBariapprovedthestudy. Written informed consentwas obtained fromthechildren’sparents.

Eligibility of Patients

Patients were recruited from 9 pri- mary care pediatricians chosen from communities throughout the territory by random selection. Children (5–14 years of age) of either gender with a diagnosis of IBS or FAP, according to the Rome II diagnostic criteria,18 valid at the time of the design of the study, were considered eligible. The diagno- sisof IBSorFAPwasbasedonaclinical interviewperformedby the samephy- sician (DrMagistà).

Childrenwere excluded if they (1) had any chronic diseases, (2) received treatment with antibiotics/probiotics in the previous 2 months, (3) had a pain history suggestive of functional dyspepsia/aerophagia/abdominal mi- graine,(4)exhibitedgrowthfailure, (5) had gastroparesis, (6) had gastroin- testinalobstructions/stricture, (7)dis- played alarming signs of organic con- ditions,18 (8) had previous abdominal surgery, or (9) hadabnormal baseline test results (including complete blood counts; erythrocyte sedimentation rate; liver-pancreas-kidney function tests; tissue transglutaminase with immunoglobulinAmeasurement;stool examination for occult blood, ova, and parasites; fecal calprotectin; urinaly- sis; 13C-urea breath test; and abdomi- nal ultrasound).

StudyDesign

The 8-week treatment period (weeks 5–12)was preceded by a 4-week run-in phase (weeks 1–4) and followed by an 8-week follow-up phase (weeks 13–20). To undergo randomization, patients must have had at least 1 episode of ab- dominal painperweekandnegative re- sults in their baseline studies. Children were assigned consecutive numbers, starting with the lowest number avail- able, andwere randomlyassigned,with the use of a computer-generated ran- domization list created by using per- muted block design, to receive either oral LGG (3 � 109 colony-formingunits) or oral placebo twice per day. Enrolled childrenwereenteredsequentiallytore- ceive theassigned treatment. Theboxes that containedplaceboand LGGhad the sameshape, theplacebo’s taste, dimen- sion, indication, and appearance were thesameas thoseof theviableLGG,and the placebowas provided by the probi- otic producer (Dicofarm SpA, Rome, Italy),whichensured that thestudywas blinded for investigators and patients. Group assignment was concealed from participantsand investigators.

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Assessments, Compliance, and Adherence

On a daily basis fromweek 1 to week 20, patients recorded the frequency/ severity of pain and school absence (Supplemental Appendix).

To assess the severity of pain, a com- binationof the self-reported visual an- alog scale (VAS) and the Faces Pain Scale (FPS)wasused. The 0- to 10-mm VAS scale (0, no pain; 10, worst possi- ble pain) included a horizontal color gradient (green to red) plus a rating. Whenasked to evaluate pain, the child would point to a level and trace a line. ThisparticularVAS is a validatedstan- dard for evaluating pain in children older than 5 years.19 Assessment was easedbycouplingtheVASwiththeFPS, which consists of 6 faces that range from a relaxed face to a face that shows intensepain.20

The impactonparents’ overall assess- mentofpain reliefwith treatmentwas obtained by interviewing them before andafter treatment. Symptomamelio- ration was assessed by the question, “How do you feel the medication re- lieves thepainof your child?” Possible answers included significant, mild, or no relief.

To ensure compliance, 1 investigator contacted the families every 4 weeks to monitor the process of the study. Adherence was assessed by counting thenumberof capsules returned; chil- dren who missed taking more than 20% of the medication were consid- erednoncompliant.

Intestinal Permeability Test

The lactulose-to-mannitol ratio (La/ Ma) test was performed 1 day before andafter the 8-week treatment period according to themethodsof Generoso et al.21 Fifty-five children with no his- tory of RAP (n � 25 female subjects; ages 5–12 years) were recruited among children of the department staff to assess the normal range of

La/Maandwerereferredtoasthecon- trol group.

OutcomeMeasures

The primary outcomewas the change in abdominal pain (frequency/sever- ity) according to the VAS score from baseline to the end of the treatment period. We chose pain as the primary outcomemeasure consistent with the proposedpointstoconsiderfor IBStri- als.17 Secondary outcomes were (1) a decreaseofat least50%inthenumber ofepisodesandintensityofpain(treat- ment success), (2) a decrease in the perception of children’s pain accord- ing to their parents, and (3)modifica- tion of intestinal permeability.

Adverse Events andDisallowed Medication

Adverse events were monitored throughout the study. Children were notallowedtoconsumeanyprobiotics or prebiotics other than those pro- vided,andtheywere instructedtocon- tinue their usual eating and physical exercise habits. Concomitant use of medications that affect gastrointesti- nal motility and/or pain perception was allowed, providing their parents registered the intake.

Statistical Analysis

With theassumption that relief of pain wouldbeexpected in70%of thosewho were receiving the probiotic and in 40% of those who were receiving the placebo, we calculated that a sample of 65 children per groupwould be re- quired. This number would allow for 90%powertoshowat leasta2.5-U(SD: 3.0) advantage of LGG over placebo with respect to pain on the basis of a 2-sided type 1 error rate of 5%.

Secondaryoutcomeswereanalyzedas binary variables. Treatment success was evaluated as either achieved or failedandasadecrease in thepercep- tion of children’s pain according to

their parents, rated as either signifi- cant orno relief. The �2 or Fisher’s ex- act test was used, as appropriate, to compare percentages and nominal variables.

For continuous variables, differences between children in the 2 treatment arms were compared by using analy- sis of variance, and the Wilcoxon test was used for comparison of themean values. The average frequency/inten- sity of pain during the run-in period wasusedasabaseline, andchange in pain frequency/intensity was mea- sured.Oddsratiosand95%confidence intervals and the number needed to treat were calculated. All statistical tests were 2-tailed and performed at the 5% level of significance. All analy- ses were performed on the intention- to-treat basis, in which all of the participants in a trial are analyzed ac- cording to the intervention to which they were assigned, regardless of whether they received it. Dataarepre- sented as mean and standard devia- tion. Data were analyzed with SPSS 13.0 software (SPSS, Chicago, IL).

RESULTS

Of 353 potential participants, 141met the inclusion criteria and were ran- domly assigned to a study group (71 subjects in the LGG group and 70 sub- jectsintheplacebogroup);83subjects had IBS, and 58 had FAP. Figure 1 shows the number of participants in- volvedinthetrial fromtheassessment for eligibility through follow-up. At the final assessment, complete datawere available for 136 of 141 participants (96%). The baseline characteristics of the participants in the 2 groups were similar (Table 1).

Primary Outcome

The number of episodes of pain per week at baseline was 3.7 (2.5) in the probiotic and 3.5 (2.4) in the placebo group. The episodes of pain at 12

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weeks decreased to 1.1 (0.8) and 2.2 (1.2), respectively (P � .01). At theend of the follow-up period, episodes of pain decreased to 0.9 (0.5) in the pro- biotic group and 1.5 (1.0) in the pla- cebo group (P � .02) (Fig 2A).

Theseverityofpainatbaselinewas4.3 (1.8) in both groups. The severity of pain at 12weekshaddecreased to 2.3 (1.3) and 3.4 (2.1), respectively (P � .01). At the end of follow-up, the epi- sodes of pain had decreased to 0.9 (0.5) intheprobioticand1.5(1.0) inthe

placebo group (P � .001) (Fig 2B). Ta- ble 2 shows the results for children with IBS and FAP.

Secondary Outcome

Treatment Success

At week 12, treatment success was achieved in48children in theLGGgroup comparedwith 37 in the placebo group (72 vs 53%; P � .03). At the end of the follow-up, treatment success was achieved in53children in theLGGgroup compared with 43 children in the pla-

cebo group (79 vs 62%; P � .03). Treat- mentsuccessatweek12wassustained atweek20.Theeffectwaspresentonlyin childrenwith IBS(Table3).

Perception of Children’s Pain According to Their Parents

Parents rated global improvement of pain after LGGuse as significant in 54% of the casesatweek12 (n � 36) and in 70%atweek20 (n � 49). In theplacebo group, a significant relief of pain was seenin33%(n�23)and55%(n�38)of the children, respectively (P � .02 and P� .04, respectively).

Intestinal Permeability Test

The intestinal permeability test (IPT) in children from the control group showed a mean La/Ma of 0.028 (0.008) (95% confidence interval: 0.025–0.034); therefore, the cutoff valueforthenormalrangewassetata La/Ma of less than 0.034.21,22 In the studypopulation, the IPTwasavailable

FIGURE 1 Enrollment, assignment, intervention, and follow-up.

TABLE1 Demographic Characteristics andBaseline Symptoms

LGG (N � 67)

Placebo (N � 69)

P

Age,mean � SD, y 6.5 � 2.1 6.3 � 2.0 .5 Male/female,n/n 43/24 35/23 .8 Frequency of pain,means � SD,n/wk 4.4 � 3.1 3.5 � 3.4 .6 Intensity of pain (VAS),mean � SD 4.3 � 2.3 4.3 � 2.2 .9 School absenteeismbecause of pain, d/mo 3 3 .9 Duration of symptoms,mean � SD, y 2.1 � 1.7 2.6 � 2.5 .7 FAP,n 25 31 .9 IBS,n 42 38 .8

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atweeks 4 and 12 in 54 cases: 49 chil- dren refused the test, and 28 did not showup fora follow-up IPT. Compared with thecontrol subjects, 32of 54chil- dren (59%) at entry had an abnormal IPT result (mean La/Ma: 0.035 [0.01], irrespectiveof thedisorder[FAP/IBS]), and it was significantly higher than in control subjects (P � .01). Atweek12, we found that LGG,butnotplacebo,de- termined a significant decrease in (1) thenumberofpatientswithanaltered IPT result (�40% vs �21%; P � .03) and (2) the La/Ma (mean La/Ma: 0.030 [0.005] vs 0.039 [0.011]; P � .02). The effectof theprobioticwasmainlyseen in children with IBS compared with thosewith FAP (Fig 3). Mean values of the percentage recovery of mannitol, lactulose, and La/Ma are reported in Table 4. We found no correlation be- tween the La/Ma test and severity of symptoms.

Compliance andSafety

Compliancewas similar in the LGG and placebo groups (89% and 86%, respec- tively).LGGwaswelltolerated,andnoad- verseeffectswerereported.

DISCUSSION

Results of this large, prospective, randomizedstudy show that LGGwas effective, over 8 weeks, for reducing the frequency and severity of pain in children with IBS. The efficacy of the

FIGURE 2 Time-trendanalysisofmeanweeklynumber(A)andseverity(B)ofepisodesofpaininchildrentreated with LGGor placebo (intention-to-treat analyses). NS indicates not significant.

TABLE2 OutcomeMeasure at Baseline andDuring Treatment and Follow-up for ChildrenWith IBS and FAP

No. of Episodes of Pain Intensity of Episodes of Pain

LGG Placebo P LGG Placebo P

IBS,N 42 38 42 38 Weeks 1–4 3.4 � 2.3 4.0 � 3.5 .2 4.4 � 2.1 4.6 � 2.8 .5 Weeks 5–12 1.6 � 0.8 3.2 � 1.9 .001 2.5 � 1.2 3.6 � 2.2 .01 Treatment success,% 79 45 .01 55 30 .1

Weeks 13–20 0.9 � 0.2 1.6 � 0.9 .001 1.8 � 0.3 3.3 � 1.5 .001 Treatment success,% 82 50 .001 72 46 .006

FAP,N 25 31 25 31 Weeks 1–4 4.2 � 2.5 3.0 � 2.1 .1 4.1 � 2.4 4.1 � 2.1 .6 Weeks 5–12 1.9 � 0.7 1.7 � 1.5 .7 2.5 � 1.6 3.1 � 1.4 .1 Treatment success,% 48 44 .6 50 60 .4

Weeks 13–20 1.1 � 0.4 1.4 � 0.9 .6 2.2 � 1.2 3.0 � 1.7 .05 Treatment success,% 84 76 .3 62 69 .7

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treatment with LGG translated into a significantly higher proportion of treatment successes and a de- creased perception of children’s pain according to their parents. For children with IBS, we could demon- strate an improvement of the intesti- nal permeability after probiotic ad- ministration. To the best of our

knowledge, this is the largest inde- pendent clinical trial to investigate the effect of probiotics in children and adolescents with chronic ab- dominal pain referred from primary care pediatricians.

Mostdataonthepossibleuseofprobi- otics in functional disorders and on

the rationale for their use are derived from studies of adults with IBS.23 For children, the issue is more compli- cated, because they complain of non- specific chronic abdominal pain that encompasses a heterogeneous group of patients. We also enrolled children with FAP, because this condition may beaprecursorof IBS inadults.24–26 The hypothesis that changes in the intesti- nal microbiota could participate in symptomgeneration in functional dis- orderswaspreviouslyproposedandis supported by recent data obtained by using real-time polymerase chain re- action techniques.27–29

Given their safety profile, probiotics seem to be an attractive therapeutic option for chronic abdominal pain. However, few data are available from childrenwiththiscondition,anddiffer- ences in study design and the use of nonvalidated and differing end points complicatetheinterpretationofthere- sults. LGGwas evaluated in 2 different randomized, placebo-controlled trials. In 1 trial, LGG was administered for 6 weeks to 50 childrenwith IBS. The au- thorsdidnotfindan increasedbenefit of theprobioticovertheplacebo,prob- ablybecauseofahighresponserate in the latter group.15 LGG was subse- quently evaluated in 104 childrenwith RAP, and treatment success (no pain) occurred in 25%of patients in the LGG groupandin10%ofpatients inthepla-

TABLE3 Treatment Success at the Endof Intervention (Week 12) and Follow-up (Week 20) for ChildrenWith IBS and FAP

Week 12 Week 20

LGG (n � 67)

Placebo (n � 69)

P LGG (n � 67)

Placebo (n � 69)

P

IBS,% 82 45 .01 87 50 .01 FAP,% 47 43 NS 74 68 NS

NS indicates not significant.

FIGURE 3 IPT results in healthy children (striped pattern) and childrenwith IBS and FAPbefore (□) and after ( ) intervention. Small-intestinebarrier functionresultsweremorealtered inchildrenwithchronic abdominal pain (both IBS and FAP) than in control subjects. At week 12, we found that LGG, but not placebo, resulted in a significant reduction of intestinal permeability in childrenwith IBS (aP � .02) but not FAP (bP � .2).

TABLE4 IPT Results at Entry andat the Endof the Intervention According to the Type of Functional Disorder

LGG,means � SD Placebo,means � SD

Week 0 Week 12 P Week 0 Week 12 P

Overall La,% recovery 0.36 � 0.09 0.31 � 0.07 .08 0.36 � 0.09 0.37 � 0.08 .07 Ma,% recovery 10.04 � 2.1 11.89 � 2.5 .02 10.09 � 1.8 10.01 � 1.8 .7 La/Ma 0.036 � 0.01 0.026 � 0.005 .002 0.038 � 0.01 0.034 � 0.01 .6 FAP La,% recovery 0.34 � 0.11 0.30 � 0.09 .2 0.37 � 0.1 0.36 � 0.1 .6 Ma,% recovery 9.9 � 2.1 11.8 � 2.5 .1 10.4 � 1.7 10.5 � 1.8 .7 La/Ma 0.034 � 0.01 0.025 � 0.006 .05 0.036 � 0.01 0.035 � 0.01 .6 IBS La,% recovery 0.38 � 0.06 0.33 � 0.05 .06 0.38 � 0.06 0.37 � 0.06 .5 Ma,% recovery 10.1 � 2.3 11.8 � 2.6 .1 9.7 � 1.8 9.7 � 1.7 .6 La/Ma 0.039 � 0.01 0.028 � 0.004 .005 0.04 � 0.01 0.038 � 0.01 .4

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cebo group (P � .03).11 Both studies had some limitations. In the study by Bausserman and Michail,15 the inulin used as a placebomay act as a prebi- otic andmight have exerted a positive effect on the indigenous health- promotingmicrobiota. In addition, the recruitment inanacademiccenter for the diagnosis and treatment of func- tionalgastrointestinaldisorders inthe study by Gawrońska et al16might have allowed for the inclusion of more se- verely affectedpatients; therefore, pa- tients were less likely to respond. Moreover, in this study, the probiotic was used for only 4 weeks, and chil- dren with dyspepsia were not ex- cluded. We tried to reduce the possi- ble confounding factors by using an inert powder for a placebo; exclud- ing children with functional dyspep- sia in whom the rational for the use of a probiotic is hard to establish, which increased the number of chil- dren enrolled; and planning the study in a primary care setting to avoid thevarious issueswithrecruit- ment in a tertiary referral popula- tion.16 Indeed, becausemost children with IBS are seen and treated in pri- mary care, itmay be speculated that the results of a trial conceived in such a setting aremore easily appli- cable to daily practice.

Probiotics have several potential mechanismsof action30–32 thatmay in- tervene in themultifactorialpathogen- esis of childhood chronic abdominal pain.33 Consistent with previous stud- ies in adults,34,35 our results yield experimental evidence that small- intestinal permeability is significantly

increased inchildrenwith IBSandthat the administration of LGG is able to ameliorate it.

The intestinal tract features amucosal epithelial cell barrier that is critical in providingthefirstlineofdefenseagainst external insults. Tight junctions repre- sent the luminal-most portion of a broader “apical junction complex,” and their disruption plays a crucial role in thepathogenesisofanumberofgastro- intestinal diseases such as inflamma- torybowel diseaseand IBS.36,37 That LGG hasadirecteffectontightjunctioninteg- rity is not surprising because LGG (1) prevents Escherichia coli–induced de- rangement of tight junctions,38 (2) se- cretes proteins that stabilize intestinal tight junctions,39 (3) reverses increased intestinal permeability caused by cow’s milk in suckling rats,40 and (4) reduces, in a rat model, the severity of alcohol- inducedguthyperpermeability.41 Thede- sign of our study does not allow us to assess whether altered intestinal per- meability is thecauseortheeffectof the functional disorder but shows that LGG hasapositiveeffectongutpermeability.

We believe that our study has some strengths, including therandomassign- ment of a high number of well- characterizedchildren, the investigation ofapossiblemechanismofactionof the probiotic,andthe long-termadministra- tionof theprobioticand follow-upofpa- tientswithevaluationof thefamilyeffect oftheintervention. Indeed,whentheout- comewas evaluated by themeasure of the familyeffect,we found that the ther- apeuticgainforLGGwas�20%overpla- cebo, which suggests a positive influ- enceoftheprobiotictherapyonparents’

perceptions of their children’s pain. Fi- nally, the long-termfollow-uphasclearly shown that the beneficial effect of the probioticextendsbeyonditsadministra- tion;therefore, itrepresentsavalidther- apeuticoption forchildrenwithRAP.

We are aware of the limitations of our study. The beneficial effectmaynot be unique toLGG,becauseotherprobiotic strainshavebeenshowntoplayapro- tectiveroleonthegutmucosalbarrier disruption.42Wehavenotperformedan analysis of the gut microbiota, which makesitdifficult tosupportthehypothe- sis thatLGGhas theability toestablisha “healthy” gut microbiotic community. Thereducednumberofchildrenwhoat- tended the IPTmay have decreased the power of the study for this particular analysis. Finally, given the chronic and relapsingnatureof functionaldisorders and the failure of supplementationwith probioticstopersistinthehumangutfor more thana fewweeksbeyond the ces- sation of administration, we cannot ex- clude thepossibility that thepositive ef- fect is temporary.

CONCLUSIONS

LGG significantly reduces the fre- quencyandseverityof abdominalpain in children with IBS. Therefore, as more probiotic compounds become available on the market or are in the process of being approved, demon- stration of the efficacy of a given pro- biotic for a specific therapeutic target will help clinicians choose which pro- biotic to usewhen dealingwith a spe- cificdisease.43Weareentering theera of targetedprobiotic use.

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