- Email: [email protected]
Changes in Fecal Calprotectin After Rifaximin Treatment in Patients With Nonconstipated Irritable Bowel Syndrome
CLINICAL INVESTIGATION
Changes in Fecal Calprotectin After Rifaximin Treatment in Patients With Nonconstipated Irritable Bowel Syndrome D1X XSeok-Hoon Lee, MD, D2X X D3X X Cho-Rong Kim, D4X XMD and Kyu-Nam D5X X Kim, D6X XMD, PhD Department of Family Practice and Community Health, Ajou University School of Medicine, Suwon, Gyeonggi-do, Republic of Korea ABSTRACT Background: Fecal calprotectin, an indicator of colonic inflammation, is associated with nonconstipated irritable bowel syndrome. Rifaximin is an antibiotic used to treat nonconstipated irritable bowel syndrome. We performed a retrospective review of patient charts to investigate the changes in fecal calprotectin levels and intestinal symptoms following treatment with rifaximin in patients with nonconstipated irritable bowel syndrome with elevated fecal calprotectin. Methods: This study included 198 patients presenting with gastrointestinal complaints consistent with Rome III criteria for irritable bowel syndrome. We treated them with rifaximin for 4-12 weeks, until fecal calprotectin levels were normalized, and divided these into 4-, 8-, and 12-week groups according to the treatment period. Fecal calprotectin levels and gastrointestinal symptoms were assessed following rifaximin therapy. Results: A total of 162 subjects achieved normalized fecal calprotectin values. Of these, most patients who used rifaximin for 8 or 12 weeks showed a significant improvement in gastrointestinal symptoms by the fourth week of treatment, and gradually improved symptoms after 4 weeks. Fecal calprotectin levels were reduced with concomitant improvement of clinical symptoms. In addition, 36 patients who had elevated fecal calprotectin even after 12 weeks of rifaximin treatment showed a gradual reduction in gastrointestinal symptoms and fecal calprotectin during the course of treatment for 12 weeks. Conclusions: These findings suggest that fecal calprotectin might be a useful biomarker for measuring the effect of rifaximin therapy in nonconstipated irritable bowel syndrome patients with elevated fecal calprotectin values. Keywords: Fecal calprotectin; Rifaximin; Irritable bowel syndrome; Small intestinal bacterial overgrowth. [Am J Med Sci 2019;357(1):23−28.]
INTRODUCTION
I
rritable bowel syndrome (IBS) is one of the most commonly diagnosed functional gastrointestinal disorders. It is characterized by recurrent abdominal symptoms that are associated with changes in bowel habits or defecation.1 The pathophysiology of IBS is complex and multifactorial, but traditionally, IBS research has focused on gastrointestinal dysmotility, visceral hypersensitivity, brain-gut dysfunction, and psychosocial stressors.2 However, emerging evidence reveals that the gut microbiome plays a significant pathological role in some IBS patients.3 Indeed, small intestinal bacterial overgrowth (SIBO) and IBS have been reported to have similar symptoms, and recently, a bacterial imbalance in the large intestine was reported to be associated with IBS.4,5 Based on these observations, a number of studies have shown improvement in symptoms when rifaximin, a nonabsorbable antibiotic, was used to treat patients with IBS.6,7 It is known that rifaximin is more effective in patients with nonconstipated subtypes of IBS,8 and
furthermore, a recent study found that the duration of treatment depends on hydrogen gas levels when SIBO is measured by lactulose hydrogen breath test in these patients.9 Clinically, SIBO is diagnosed by hydrogen breath test, as there is no standard tool for diagnosing bacterial imbalance in the colon. Therefore, in clinical practice, fecal calprotectin (FC), an inflammatory indicator of the colon, is used to gauge bacterial imbalance or to determine the degree of disease activity in the large intestine.10,11 Nonconstipated IBS has been associated with altered gut microbiota in the colon, which is in turn associated with elevated FC.12 To the best of our knowledge, no study has yet investigated the changes in FC levels following rifaximin therapy in these patients. In our practice, we have used rifaximin in nonconstipated IBS patients with elevated FC levels since 2015, and we now report on our experience using rifaximin. In the present study, we performed a retrospective chart review in order to investigate whether FC values and intestinal
Copyright © 2018 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved. www.amjmedsci.com www.ssciweb.org
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Lee et al
symptoms are altered by rifaximin, and furthermore, observed the effect of treatment duration in nonconstipated IBS patients with elevated FC. In addition, we examined whether baseline FC values had any relationship to overall abdominal symptoms.
METHODS Study Population The subjects were identified through the scheduling database of the Department of Family Medicine and the Health Promotion Center at Ajou University Hospital, Suwon, Korea for the period between January 2015 and May 2017. We included subjects who had undergone gastroduodenoscopy, colonoscopy, and abdomen ultrasonography within the prior 2 years from the time of the hospital visit. Patients over 20 years of age who had abdominal symptoms, such as abdominal discomfort and abnormal bowel habit changes at the time of the hospital visit were interviewed by a physician. IBS was diagnosed based on Rome III criteria. In addition, additional FC tests were performed in these patients. The stool samples for FC tests were sent to the Institute of Applied Technology for Green Cross LabCell (Yongin, Korea), where the level of calprotectin in the stool specimens was measured using an ImmunoCAP 250 (Aloka, Japan) with Calprotectin FEIA (fluorescence enzyme immunoassay) kit (Phadia AB, Sweden). A normal FC value was defined as ˂11.5 mg/kg, as it was unmeasurable below this level. A total of 616 patients were identified through an electronic database search. Among these, 375 were
excluded for the following reasons: constipationpredominant IBS (102 patients); negative result on initial FC (173 patients); history of other gastrointestinal disorders such as inflammatory bowel disease, peptic ulcer disease or cancer (22 patients); use of antibiotics, probiotics, or any other drug that can influence bowel function (78 patients). We selected 241 nonconstipated IBS patients with documented elevated FC values during the initial visit, and those with poor medication compliance were also excluded (43 patients). Finally, 198 patients who performed the follow-up FC test after treatment with rifaximin were ultimately analyzed for this study (Figure 1).
Study Design Study subjects typically received initial rifaximin treatment of 1200 mg/day for 4 weeks at baseline, then subsequently underwent follow-up FC tests after the initial treatment period. If follow-up FC levels were >11.5 mg/kg, subjects were maintained on rifaximin treatment and retook an FC test every 4 weeks until their levels were normalized. Rifaximin was discontinued after 12 weeks of treatment, although elevated values of FC could still be observed in some subjects. This was because of rifaximin resistance, as previous studies have reported that rifaximin resistance may develop in nondigestive organs by prolonged use of rifaximin.13,14 Since the prevalence of Mycobacterium tuberculosis is higher in Korea, doctors should take note of rifaximin resistance. The 4-week-interval clinical protocol with rifaximin was based on a previous study in which hydrogen/
FIGURE 1. Flow diagram of subject inclusion and exclusion for this study. Abbreviations: FC, fecal calprotectin; GI, gastrointestinal; IBS, irritable bowel syndrome; LHBT, lactulose hydrogen breath test.
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Fecal Calprotectin and Rifaximin Treatment
methane breath test was retested after 4 weeks of treatment with rifaximin in nonconstipated IBS patients.9 In addition, we used a 4-week treatment period because there was a previous study that reported a frequent recurrence of symptoms when treated with rifaximin for only 2 weeks in patients with IBS.15 We categorized study subjects into 3 groups according to their treatment duration: 4 weeks, 8 weeks, and 12 weeks. The severity of global abdominal symptoms was described using global abdominal symptoms on a 7-point Likert scale (0, hardly any; 1, hardly; 2, somewhat; 3, moderately; 4, a good deal; 5, a great deal; and 6, a very great deal). The Likert scale was recorded for each patient visit. Statistical Analysis The data were analyzed in order to evaluate the relief of global IBS symptoms during each visit, and to determine the duration necessary to achieve a successful treatment response, which was defined as a normalized FC value. One-way analysis of variance was used to compare among categories of treatment duration. In order to assess the relationship between the initial overall abdominal Likert scale results and the baseline FC values, Pearson correlation coefficient analysis was used. A paired t test was performed in order to evaluate Likert scale change following rifaximin treatment. All statistical analyses were carried out using PASW SPSS Statistics for Windows version 19.0 (IBM, Chicago, IL). Ethics Statement This study was approved by the institutional review board of the Ajou University Hospital (IRB No. MEDMDB-18-335). The requirement of informed consent was waived by the board.
RESULTS Table 1 shows the characteristics of subjects according to normalization of FC value by rifaximin treatment. A total of 162 subjects achieved normalized FC values. Of these, 115 subjects (71.0%) received treatment for 4 weeks, 39 subjects (24.1%) for 8 weeks, and 8 subjects (4.9%) for 12 weeks. Ninety-eight subjects (60.5%) were male and 64 subjects (39.5%) were female. Thirty-six patients showed persistent increases in FC despite
3 months of treatment. The mean age of subjects in these groups was 45.7 § 10.7 years. The changes in mean FC values and abdominal symptoms according to treatment duration are shown in Table 2. The mean baseline values were 84.5, 136.4, and 95.4 for 4-week, 8-week, and 12-week treatments, respectively, and these were not significantly different between treatment duration categories (P value = 0.137). In addition, a correlation analysis between initial symptoms and FC results showed no significant relationship between global symptoms and FC values during the initial visit (data not shown). Initial Likert scales were 4.4 § 0.8, 4.5 § 0.7, and 4.7 § 1.0 in 4-week, 8-week, and 12-week treatment groups, respectively. Most of the patients treated for 8 or 12 weeks showed a greater improvement in symptoms compared to baseline at 4 weeks, and gradually improved symptoms thereafter. In most cases, symptomatic improvement was observed earlier than the time at which the FC values had normalized. Figure 2 shows changes in mean FC values and abdominal symptoms in the patients with persistently elevated FC levels after a 12-week treatment. A total of 36 subjects had a high value after 12 weeks of treatment, and the mean values were 183.8 at baseline and 81.2 at 12 weeks. Similar to groups with normalized FC after a 12-week treatment, most subjects with persistent elevated FC showed a measurable improvement of abdominal symptoms, and the most significant treatment response was observed during the first 4 weeks.
DISCUSSION We hypothesized that rifaximin therapy in patients with nonconstipated IBS with elevated FC values would reduce FC and improve bowel symptoms. In addition, we observed that changes in FC values were correlated with changes in digestive symptoms. In this study, we found that patients treated with rifaximin for more than 2 months had already begun to show improved abdominal symptoms after 1 month of treatment, despite the fact that FC values were not normalized at 1 month after treatment. Furthermore, even patients who were treated for up to 3 months without achieving normalized FC values showed improvement in symptoms. Calprotectin is present in plasma and stools, and FC is usually higher than seen in plasma.16 FC is resistant to
TABLE 1. Characteristics of subjects according to normalization of FC value by rifaximin treatment. FC values were normalized within 12 weeks (n = 162) Characteristics No. of subjects (%) Sex (M/F) Age (years)
FC values were not normalized within 12 weeks (n = 36)
4 weeks
8 weeks
12 weeks
Not normalized
115 (71.0) 72/43 45.6 § 10.3
39 (24.1) 23/16 46.5 § 9.8
8 (4.9) 3/5 44.1 § 14.8
36 26/10 45.7 § 10.7
Abbreviations: F, female; FC, fecal calprotectin; M, male; No, number.
Copyright © 2018 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved. www.amjmedsci.com www.ssciweb.org
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TABLE 2. Mean values for initial and follow-up fecal calprotectin and Likert scale based on treatment duration Treatment duration 4 weeks group (n = 115) 8 weeks group (n = 39) 12 weeks group (n = 8) P value**
Fecal calprotectin Likert scale Fecal calprotectin Likert scale Fecal calprotectin Likert scale
Initial visit
4 weeks
8 weeks
12 weeks
84.5 § 131.8 4.4 § 0.8 136.4 § 216.7 4.5 § 0.7 95.4 § 91.5 4.7 § 1.0 0.137
< 11.5 mg/kg 2.1 § 0.7 91.7 § 144.1 2.9 § 0.9 125.5 § 209.1 3.1 § 0.8
< 11.5 mg/kg 2.2 § 0.8 123.5 § 280.8 2.3 § 0.9
< 11.5 mg/kg 1.9 § 0.9
P ˗ value* <0.05 <0.05 <0.05
Values are presented as mean § standard error. *Statistically significant between initial and final scores. ** One-way analysis of variance was used to compare initial fecal calprotectin values among categories of treatment duration.
bacterial degradation, is stable in fecal samples for up to 1 week at room temperature and is readily measured using immunochemical techniques.17 The amount of FC corresponds to neutrophil migration through the intestinal wall and increases with the severity of gut inflammation.18 Thus, elevated FC reflects a low-grade inflammation of intestinal mucosa.19 A representative disease associated with inflammation of the colon is inflammatory bowel disease. Therefore, many studies related to FC have been performed in inflammatory bowel disease. However, recent studies have shown that colonic inflammation is associated with IBS as well. Chang et al20 have shown that FC values are increased in IBS patients. David et al21 showed that elevated FC values were more frequent in postinfectious-IBS patients than in nonpostinfectious-IBS patients. In addition, a recently published study reported that FC was not only helpful in the diagnosis of IBS, but also positively correlated with physical components of health-related quality of life.22 Furthermore, Tibble et al23 proposed that the
combination of FC value (cut-off levels of 30 mg/kg) and Rome criteria can diagnose IBS without any further examination. Therefore, the use of FC as a biomarker of gut inflammation could be used not only for screening inflammatory bowel disease, but also for therapeutic approaches to IBS. The present study was based on these emerging pieces of evidence suggesting that lowgrade inflammation of the colon is a characteristic of IBS. Consistent with this literature, we observed reductions in FC and improvement of intestinal symptoms when IBS patients with elevated FC were treated with rifaximin. Mounting evidence also shows that rifaximin is an effective option for the treatment of IBS without constipation.7,24 However, there has not yet been a study addressing the appropriate period of rifaximin treatment based on FC values in patients with nonconstipated IBS. Thus, we focused on the correlation between FC levels and rifaximin treatment duration. We found that there was no significant relationship between treatment period and baseline FC values. In addition, FC values were not
FIGURE 2. Mean values of the initial and follow-up fecal calprotectin and Likert scale in patients with persistent elevated fecal calprotectin levels after a 12-week treatment (n = 36).
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correlated with the severity of the symptoms, and even patients with persistent FC elevation following treatment had improved overall abdominal symptoms. These findings suggest that the FC value is not related to the duration of treatment or the degree of abdominal symptoms in patients with nonconstipated IBS. Interestingly, the patients whose FC values were normalized after 3 months of rifaximin treatment had slightly higher FC values at 1-month after treatment than the pretreatment FC, although their symptoms were gradually relieved. One possible hypothesis for why FC values were elevated temporarily following treatment may be that the reduction of harmful bacteria caused by rifaximin treatment leads to a temporary rise in lipopolysaccharides, thereby improving abdominal symptoms while simultaneously increasing FC. On the other hand, we found that improvement of symptoms after rifaximin treatment was shown earlier than the normalization of FC values. In addition, we found that some patients with IBS had a sustained elevation of FC despite 3-month treatment with rifaximin, but had improved symptoms compared to before treatment. Taken together, these findings suggest that if rifaximin treatment is based on IBS symptoms, treatment may be terminated prematurely despite persistent intestinal inflammation. In addition, frequent relapse of symptoms after the 2 weeks of rifaximin treatment may be due to colonic inflammation that have not yet been normalized. Furthermore, this study suggests that subjects do not develop clinical resistance because after 12 weeks of rifaximin administration, even subjects with elevated FC results had a decrease in their FC values and symptoms gradually improved. Our study had limitations. First, this study was a retrospective chart review, which is associated with selection and information bias. Second, some patients in our data failed to follow up. Therefore, patients who showed good compliance could conceivably bias the results. Third, we have not applied the Rome IV criteria, published in 2016, to the diagnosis of IBS for the consistency of the study subjects, since we collected research data from 2015. Nevertheless, it may be noteworthy that this is the first study to show that rifaximin treatment modifies the digestive symptoms and FC values in patients with IBS with elevated FC values.
CONCLUSIONS In conclusion, we evaluated the changes in FC levels and intestinal symptoms following treatment with rifaximin in nonconstipated IBS patients with elevated FC values. The clinical chart review of subjects with rifaximin-mediated FC change demonstrated that treatment with rifaximin showed a decreased FC value and improvement in bowel symptoms. These findings suggest that FC value might be an additional marker for
measuring the effect of rifaximin treatment in patients with nonconstipated IBS.
AUTHOR CONTRIBUTIONS K.N.K. designed the study; S.H.L. and C.R.K. carried out the data collection and conducted the statistical analysis; S.H.L. wrote the original draft; S.H.L. and K.N. K. were involved in editing and review. All authors read and approved the final manuscript.
REFERENCES 1. Lacy BE, Patel NK. Rome criteria and a diagnostic approach to irritable bowel syndrome. J Clin Med. 2017;6(11). 2. Chey WD, Kurlander J, Eswaran S. Irritable bowel syndrome: a clinical review. JAMA. 2015;313(9):949–958. 3. Simren M, Barbara G, Flint HJ, et al. Intestinal microbiota in functional bowel disorders: a Rome foundation report. Gut. 2013;62(1):159–176. 4. Dupont HL. Review article: evidence for the role of gut microbiota in irritable bowel syndrome and its potential influence on therapeutic targets. Aliment Pharmacol Ther. 2014;39(10):1033–1042. 5. Holtmann G, Shah A, Morrison M. Pathophysiology of functional gastrointestinal disorders: a holistic overview. Dig Dis. 2017;35(Suppl 1):5–13. 6. Pimentel M, Park S, Mirocha J, et al. The effect of a nonabsorbed oral antibiotic (rifaximin) on the symptoms of the irritable bowel syndrome: a randomized trial. Ann Intern Med. 2006;145(8):557–563. 7. Pimentel M, Lembo A, Chey WD, et al. Rifaximin therapy for patients with irritable bowel syndrome without constipation. N Engl J Med. 2011;364(1):22–32. 8. Lembo A, Zakko SF, Ferreira NL, et al. T1390 rifaximin for the treatment of diarrhea-associated irritable bowel syndrome: short term treatment leading to long term sustained response. Gastroenterology. 2008;134(4):A–545. 9. Bae S, Lee KJ, Kim YS, et al. Determination of rifaximin treatment period according to lactulose breath test values in nonconstipated irritable bowel syndrome subjects. J Korean Med Sci. 2015;30(6):757–762. 10. Costa F, Mumolo MG, Bellini M, et al. Role of faecal calprotectin as non-invasive marker of intestinal inflammation. Dig Liver Dis. 2003;35 (9):642–647. 11. Shaw KA, Bertha M, Hofmekler T, et al. Dysbiosis, inflammation, and response to treatment: a longitudinal study of pediatric subjects with newly diagnosed inflammatory bowel disease. Genome Med. 2016;8(1):75. 12. Enck P, Aziz Q, Barbara G, et al. Irritable bowel syndrome. Nat Rev Dis Primers. 2016;2:16014. 13. Calanni F, Renzulli C, Fogli MV, et al. Comment on: Rifaximin in the treatment of irritable bowel syndrome. is there a high risk for development of antimicrobial resistance? J Clin Gastroenterol. 2013;47(9):814. 14. Menees SB, Maneerattannaporn M, Kim HM, et al. The efficacy and safety of rifaximin for the irritable bowel syndrome: a systematic review and meta-analysis. Am J Gastroenterol. 2012;107(1):28–35. quiz 36. 15. Pimentel M, Morales W, Chua K, et al. Effects of rifaximin treatment and retreatment in nonconstipated IBS subjects. Dig Dis Sci. 2011;56 (7):2067–2072. 16. Summerton CB, Longlands MG, Wiener K, et al. Faecal calprotectin: a marker of inflammation throughout the intestinal tract. Eur J Gastroenterol Hepatol. 2002;14(8):841–845. 17. Siddiqui I, Majid H, Abid S. Update on clinical and research application of fecal biomarkers for gastrointestinal diseases. World J Gastrointest Pharmacol Ther. 2017;8(1):39–46. 18. Roseth AG, Aadland E, Jahnsen J, et al. Assessment of disease activity in ulcerative colitis by faecal calprotectin, a novel granulocyte marker protein. Digestion. 1997;58(2):176–180. 19. Clarke G, Quigley EM, Cryan JF, et al. Irritable bowel syndrome: towards biomarker identification. Trends Mol Med. 2009;15(10):478–489.
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20. Chang MH, Chou JW, Chen SM, et al. Faecal calprotectin as a novel biomarker for differentiating between inflammatory bowel disease and irritable bowel syndrome. Mol Med Rep. 2014;10(1):522–526. 21. David LE, Surdea-Blaga T, Dumitrascu DL. Semiquantitative fecal calprotectin test in postinfectious and non-postinfectious irritable bowel syndrome: cross-sectional study. Sao Paulo Med J. 2015;133(4):343–349. 22. Pletikosic S, Plavsic I, Hauser G, et al. Fecal Calprotectin and serum chromogranin A as potential biomarkers of irritable bowel syndrome symptom severity. Med Hypotheses. 2015;85(3):339–342. 23. Tibble JA, Sigthorsson G, Foster R, et al. Use of surrogate markers of inflammation and Rome criteria to distinguish organic from nonorganic intestinal disease. Gastroenterology. 2002;123(2):450–460.
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24. Lembo A, Pimentel M, Rao SS, et al. Repeat treatment with rifaximin is safe and effective in patients with diarrhea-predominant irritable bowel syndrome. Gastroenterology. 2016;151(6):1113–1121.
Submitted June 6, 2018; accepted November 7, 2018. Conflict of interest statement: The authors report no conflicts of interest. Correspondence: Kyu-Nam Kim, MD, PhD, Department of Family Practice and Community Health, Ajou University School of Medicine, 164 Worldcup-ro, Youngtong-gu, Suwon, Gyeonggi-do 16499, Republic of Korea. (E-mail: [email protected]).
THE AMERICAN JOURNAL OF THE MEDICAL SCIENCES VOLUME 357 NUMBER 1 JANUARY 2019
Changes in Fecal Calprotectin After Rifaximin Treatment in Patients With Nonconstipated Irritable Bowel Syndrome D1X XSeok-Hoon Lee, MD, D2X X D3X X Cho-Rong Kim, D4X XMD and Kyu-Nam D5X X Kim, D6X XMD, PhD Department of Family Practice and Community Health, Ajou University School of Medicine, Suwon, Gyeonggi-do, Republic of Korea ABSTRACT Background: Fecal calprotectin, an indicator of colonic inflammation, is associated with nonconstipated irritable bowel syndrome. Rifaximin is an antibiotic used to treat nonconstipated irritable bowel syndrome. We performed a retrospective review of patient charts to investigate the changes in fecal calprotectin levels and intestinal symptoms following treatment with rifaximin in patients with nonconstipated irritable bowel syndrome with elevated fecal calprotectin. Methods: This study included 198 patients presenting with gastrointestinal complaints consistent with Rome III criteria for irritable bowel syndrome. We treated them with rifaximin for 4-12 weeks, until fecal calprotectin levels were normalized, and divided these into 4-, 8-, and 12-week groups according to the treatment period. Fecal calprotectin levels and gastrointestinal symptoms were assessed following rifaximin therapy. Results: A total of 162 subjects achieved normalized fecal calprotectin values. Of these, most patients who used rifaximin for 8 or 12 weeks showed a significant improvement in gastrointestinal symptoms by the fourth week of treatment, and gradually improved symptoms after 4 weeks. Fecal calprotectin levels were reduced with concomitant improvement of clinical symptoms. In addition, 36 patients who had elevated fecal calprotectin even after 12 weeks of rifaximin treatment showed a gradual reduction in gastrointestinal symptoms and fecal calprotectin during the course of treatment for 12 weeks. Conclusions: These findings suggest that fecal calprotectin might be a useful biomarker for measuring the effect of rifaximin therapy in nonconstipated irritable bowel syndrome patients with elevated fecal calprotectin values. Keywords: Fecal calprotectin; Rifaximin; Irritable bowel syndrome; Small intestinal bacterial overgrowth. [Am J Med Sci 2019;357(1):23−28.]
INTRODUCTION
I
rritable bowel syndrome (IBS) is one of the most commonly diagnosed functional gastrointestinal disorders. It is characterized by recurrent abdominal symptoms that are associated with changes in bowel habits or defecation.1 The pathophysiology of IBS is complex and multifactorial, but traditionally, IBS research has focused on gastrointestinal dysmotility, visceral hypersensitivity, brain-gut dysfunction, and psychosocial stressors.2 However, emerging evidence reveals that the gut microbiome plays a significant pathological role in some IBS patients.3 Indeed, small intestinal bacterial overgrowth (SIBO) and IBS have been reported to have similar symptoms, and recently, a bacterial imbalance in the large intestine was reported to be associated with IBS.4,5 Based on these observations, a number of studies have shown improvement in symptoms when rifaximin, a nonabsorbable antibiotic, was used to treat patients with IBS.6,7 It is known that rifaximin is more effective in patients with nonconstipated subtypes of IBS,8 and
furthermore, a recent study found that the duration of treatment depends on hydrogen gas levels when SIBO is measured by lactulose hydrogen breath test in these patients.9 Clinically, SIBO is diagnosed by hydrogen breath test, as there is no standard tool for diagnosing bacterial imbalance in the colon. Therefore, in clinical practice, fecal calprotectin (FC), an inflammatory indicator of the colon, is used to gauge bacterial imbalance or to determine the degree of disease activity in the large intestine.10,11 Nonconstipated IBS has been associated with altered gut microbiota in the colon, which is in turn associated with elevated FC.12 To the best of our knowledge, no study has yet investigated the changes in FC levels following rifaximin therapy in these patients. In our practice, we have used rifaximin in nonconstipated IBS patients with elevated FC levels since 2015, and we now report on our experience using rifaximin. In the present study, we performed a retrospective chart review in order to investigate whether FC values and intestinal
Copyright © 2018 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved. www.amjmedsci.com www.ssciweb.org
23
Lee et al
symptoms are altered by rifaximin, and furthermore, observed the effect of treatment duration in nonconstipated IBS patients with elevated FC. In addition, we examined whether baseline FC values had any relationship to overall abdominal symptoms.
METHODS Study Population The subjects were identified through the scheduling database of the Department of Family Medicine and the Health Promotion Center at Ajou University Hospital, Suwon, Korea for the period between January 2015 and May 2017. We included subjects who had undergone gastroduodenoscopy, colonoscopy, and abdomen ultrasonography within the prior 2 years from the time of the hospital visit. Patients over 20 years of age who had abdominal symptoms, such as abdominal discomfort and abnormal bowel habit changes at the time of the hospital visit were interviewed by a physician. IBS was diagnosed based on Rome III criteria. In addition, additional FC tests were performed in these patients. The stool samples for FC tests were sent to the Institute of Applied Technology for Green Cross LabCell (Yongin, Korea), where the level of calprotectin in the stool specimens was measured using an ImmunoCAP 250 (Aloka, Japan) with Calprotectin FEIA (fluorescence enzyme immunoassay) kit (Phadia AB, Sweden). A normal FC value was defined as ˂11.5 mg/kg, as it was unmeasurable below this level. A total of 616 patients were identified through an electronic database search. Among these, 375 were
excluded for the following reasons: constipationpredominant IBS (102 patients); negative result on initial FC (173 patients); history of other gastrointestinal disorders such as inflammatory bowel disease, peptic ulcer disease or cancer (22 patients); use of antibiotics, probiotics, or any other drug that can influence bowel function (78 patients). We selected 241 nonconstipated IBS patients with documented elevated FC values during the initial visit, and those with poor medication compliance were also excluded (43 patients). Finally, 198 patients who performed the follow-up FC test after treatment with rifaximin were ultimately analyzed for this study (Figure 1).
Study Design Study subjects typically received initial rifaximin treatment of 1200 mg/day for 4 weeks at baseline, then subsequently underwent follow-up FC tests after the initial treatment period. If follow-up FC levels were >11.5 mg/kg, subjects were maintained on rifaximin treatment and retook an FC test every 4 weeks until their levels were normalized. Rifaximin was discontinued after 12 weeks of treatment, although elevated values of FC could still be observed in some subjects. This was because of rifaximin resistance, as previous studies have reported that rifaximin resistance may develop in nondigestive organs by prolonged use of rifaximin.13,14 Since the prevalence of Mycobacterium tuberculosis is higher in Korea, doctors should take note of rifaximin resistance. The 4-week-interval clinical protocol with rifaximin was based on a previous study in which hydrogen/
FIGURE 1. Flow diagram of subject inclusion and exclusion for this study. Abbreviations: FC, fecal calprotectin; GI, gastrointestinal; IBS, irritable bowel syndrome; LHBT, lactulose hydrogen breath test.
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Fecal Calprotectin and Rifaximin Treatment
methane breath test was retested after 4 weeks of treatment with rifaximin in nonconstipated IBS patients.9 In addition, we used a 4-week treatment period because there was a previous study that reported a frequent recurrence of symptoms when treated with rifaximin for only 2 weeks in patients with IBS.15 We categorized study subjects into 3 groups according to their treatment duration: 4 weeks, 8 weeks, and 12 weeks. The severity of global abdominal symptoms was described using global abdominal symptoms on a 7-point Likert scale (0, hardly any; 1, hardly; 2, somewhat; 3, moderately; 4, a good deal; 5, a great deal; and 6, a very great deal). The Likert scale was recorded for each patient visit. Statistical Analysis The data were analyzed in order to evaluate the relief of global IBS symptoms during each visit, and to determine the duration necessary to achieve a successful treatment response, which was defined as a normalized FC value. One-way analysis of variance was used to compare among categories of treatment duration. In order to assess the relationship between the initial overall abdominal Likert scale results and the baseline FC values, Pearson correlation coefficient analysis was used. A paired t test was performed in order to evaluate Likert scale change following rifaximin treatment. All statistical analyses were carried out using PASW SPSS Statistics for Windows version 19.0 (IBM, Chicago, IL). Ethics Statement This study was approved by the institutional review board of the Ajou University Hospital (IRB No. MEDMDB-18-335). The requirement of informed consent was waived by the board.
RESULTS Table 1 shows the characteristics of subjects according to normalization of FC value by rifaximin treatment. A total of 162 subjects achieved normalized FC values. Of these, 115 subjects (71.0%) received treatment for 4 weeks, 39 subjects (24.1%) for 8 weeks, and 8 subjects (4.9%) for 12 weeks. Ninety-eight subjects (60.5%) were male and 64 subjects (39.5%) were female. Thirty-six patients showed persistent increases in FC despite
3 months of treatment. The mean age of subjects in these groups was 45.7 § 10.7 years. The changes in mean FC values and abdominal symptoms according to treatment duration are shown in Table 2. The mean baseline values were 84.5, 136.4, and 95.4 for 4-week, 8-week, and 12-week treatments, respectively, and these were not significantly different between treatment duration categories (P value = 0.137). In addition, a correlation analysis between initial symptoms and FC results showed no significant relationship between global symptoms and FC values during the initial visit (data not shown). Initial Likert scales were 4.4 § 0.8, 4.5 § 0.7, and 4.7 § 1.0 in 4-week, 8-week, and 12-week treatment groups, respectively. Most of the patients treated for 8 or 12 weeks showed a greater improvement in symptoms compared to baseline at 4 weeks, and gradually improved symptoms thereafter. In most cases, symptomatic improvement was observed earlier than the time at which the FC values had normalized. Figure 2 shows changes in mean FC values and abdominal symptoms in the patients with persistently elevated FC levels after a 12-week treatment. A total of 36 subjects had a high value after 12 weeks of treatment, and the mean values were 183.8 at baseline and 81.2 at 12 weeks. Similar to groups with normalized FC after a 12-week treatment, most subjects with persistent elevated FC showed a measurable improvement of abdominal symptoms, and the most significant treatment response was observed during the first 4 weeks.
DISCUSSION We hypothesized that rifaximin therapy in patients with nonconstipated IBS with elevated FC values would reduce FC and improve bowel symptoms. In addition, we observed that changes in FC values were correlated with changes in digestive symptoms. In this study, we found that patients treated with rifaximin for more than 2 months had already begun to show improved abdominal symptoms after 1 month of treatment, despite the fact that FC values were not normalized at 1 month after treatment. Furthermore, even patients who were treated for up to 3 months without achieving normalized FC values showed improvement in symptoms. Calprotectin is present in plasma and stools, and FC is usually higher than seen in plasma.16 FC is resistant to
TABLE 1. Characteristics of subjects according to normalization of FC value by rifaximin treatment. FC values were normalized within 12 weeks (n = 162) Characteristics No. of subjects (%) Sex (M/F) Age (years)
FC values were not normalized within 12 weeks (n = 36)
4 weeks
8 weeks
12 weeks
Not normalized
115 (71.0) 72/43 45.6 § 10.3
39 (24.1) 23/16 46.5 § 9.8
8 (4.9) 3/5 44.1 § 14.8
36 26/10 45.7 § 10.7
Abbreviations: F, female; FC, fecal calprotectin; M, male; No, number.
Copyright © 2018 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved. www.amjmedsci.com www.ssciweb.org
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TABLE 2. Mean values for initial and follow-up fecal calprotectin and Likert scale based on treatment duration Treatment duration 4 weeks group (n = 115) 8 weeks group (n = 39) 12 weeks group (n = 8) P value**
Fecal calprotectin Likert scale Fecal calprotectin Likert scale Fecal calprotectin Likert scale
Initial visit
4 weeks
8 weeks
12 weeks
84.5 § 131.8 4.4 § 0.8 136.4 § 216.7 4.5 § 0.7 95.4 § 91.5 4.7 § 1.0 0.137
< 11.5 mg/kg 2.1 § 0.7 91.7 § 144.1 2.9 § 0.9 125.5 § 209.1 3.1 § 0.8
< 11.5 mg/kg 2.2 § 0.8 123.5 § 280.8 2.3 § 0.9
< 11.5 mg/kg 1.9 § 0.9
P ˗ value* <0.05 <0.05 <0.05
Values are presented as mean § standard error. *Statistically significant between initial and final scores. ** One-way analysis of variance was used to compare initial fecal calprotectin values among categories of treatment duration.
bacterial degradation, is stable in fecal samples for up to 1 week at room temperature and is readily measured using immunochemical techniques.17 The amount of FC corresponds to neutrophil migration through the intestinal wall and increases with the severity of gut inflammation.18 Thus, elevated FC reflects a low-grade inflammation of intestinal mucosa.19 A representative disease associated with inflammation of the colon is inflammatory bowel disease. Therefore, many studies related to FC have been performed in inflammatory bowel disease. However, recent studies have shown that colonic inflammation is associated with IBS as well. Chang et al20 have shown that FC values are increased in IBS patients. David et al21 showed that elevated FC values were more frequent in postinfectious-IBS patients than in nonpostinfectious-IBS patients. In addition, a recently published study reported that FC was not only helpful in the diagnosis of IBS, but also positively correlated with physical components of health-related quality of life.22 Furthermore, Tibble et al23 proposed that the
combination of FC value (cut-off levels of 30 mg/kg) and Rome criteria can diagnose IBS without any further examination. Therefore, the use of FC as a biomarker of gut inflammation could be used not only for screening inflammatory bowel disease, but also for therapeutic approaches to IBS. The present study was based on these emerging pieces of evidence suggesting that lowgrade inflammation of the colon is a characteristic of IBS. Consistent with this literature, we observed reductions in FC and improvement of intestinal symptoms when IBS patients with elevated FC were treated with rifaximin. Mounting evidence also shows that rifaximin is an effective option for the treatment of IBS without constipation.7,24 However, there has not yet been a study addressing the appropriate period of rifaximin treatment based on FC values in patients with nonconstipated IBS. Thus, we focused on the correlation between FC levels and rifaximin treatment duration. We found that there was no significant relationship between treatment period and baseline FC values. In addition, FC values were not
FIGURE 2. Mean values of the initial and follow-up fecal calprotectin and Likert scale in patients with persistent elevated fecal calprotectin levels after a 12-week treatment (n = 36).
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Fecal Calprotectin and Rifaximin Treatment
correlated with the severity of the symptoms, and even patients with persistent FC elevation following treatment had improved overall abdominal symptoms. These findings suggest that the FC value is not related to the duration of treatment or the degree of abdominal symptoms in patients with nonconstipated IBS. Interestingly, the patients whose FC values were normalized after 3 months of rifaximin treatment had slightly higher FC values at 1-month after treatment than the pretreatment FC, although their symptoms were gradually relieved. One possible hypothesis for why FC values were elevated temporarily following treatment may be that the reduction of harmful bacteria caused by rifaximin treatment leads to a temporary rise in lipopolysaccharides, thereby improving abdominal symptoms while simultaneously increasing FC. On the other hand, we found that improvement of symptoms after rifaximin treatment was shown earlier than the normalization of FC values. In addition, we found that some patients with IBS had a sustained elevation of FC despite 3-month treatment with rifaximin, but had improved symptoms compared to before treatment. Taken together, these findings suggest that if rifaximin treatment is based on IBS symptoms, treatment may be terminated prematurely despite persistent intestinal inflammation. In addition, frequent relapse of symptoms after the 2 weeks of rifaximin treatment may be due to colonic inflammation that have not yet been normalized. Furthermore, this study suggests that subjects do not develop clinical resistance because after 12 weeks of rifaximin administration, even subjects with elevated FC results had a decrease in their FC values and symptoms gradually improved. Our study had limitations. First, this study was a retrospective chart review, which is associated with selection and information bias. Second, some patients in our data failed to follow up. Therefore, patients who showed good compliance could conceivably bias the results. Third, we have not applied the Rome IV criteria, published in 2016, to the diagnosis of IBS for the consistency of the study subjects, since we collected research data from 2015. Nevertheless, it may be noteworthy that this is the first study to show that rifaximin treatment modifies the digestive symptoms and FC values in patients with IBS with elevated FC values.
CONCLUSIONS In conclusion, we evaluated the changes in FC levels and intestinal symptoms following treatment with rifaximin in nonconstipated IBS patients with elevated FC values. The clinical chart review of subjects with rifaximin-mediated FC change demonstrated that treatment with rifaximin showed a decreased FC value and improvement in bowel symptoms. These findings suggest that FC value might be an additional marker for
measuring the effect of rifaximin treatment in patients with nonconstipated IBS.
AUTHOR CONTRIBUTIONS K.N.K. designed the study; S.H.L. and C.R.K. carried out the data collection and conducted the statistical analysis; S.H.L. wrote the original draft; S.H.L. and K.N. K. were involved in editing and review. All authors read and approved the final manuscript.
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Submitted June 6, 2018; accepted November 7, 2018. Conflict of interest statement: The authors report no conflicts of interest. Correspondence: Kyu-Nam Kim, MD, PhD, Department of Family Practice and Community Health, Ajou University School of Medicine, 164 Worldcup-ro, Youngtong-gu, Suwon, Gyeonggi-do 16499, Republic of Korea. (E-mail: [email protected]).
THE AMERICAN JOURNAL OF THE MEDICAL SCIENCES VOLUME 357 NUMBER 1 JANUARY 2019