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Interventions for treating iron deficiency anaemia in inflammatory bowel disease.
Gordon, M, Sinopoulou, V, Iheozor-Ejiofor, Z, Iqbal, T, Allen, P, Hoque, S, Engineer, J, Akobeng, AK
The Cochrane database of systematic reviews. 2021;(1):CD013529
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Abstract
BACKGROUND Inflammatory bowel disease affects approximately seven million people globally. Iron deficiency anaemia can occur as a common systemic manifestation, with a prevalence of up to 90%, which can significantly affect quality of life, both during periods of active disease or in remission. It is important that iron deficiency anaemia is treated effectively and not be assumed to be a normal finding of inflammatory bowel disease. The various routes of iron administration, doses and preparations present varying advantages and disadvantages, and a significant proportion of people experience adverse effects with current therapies. Currently, no consensus has been reached amongst physicians as to which treatment path is most beneficial. OBJECTIVES The primary objective was to evaluate the efficacy and safety of the interventions for the treatment of iron deficiency anaemia in people with inflammatory bowel disease. SEARCH METHODS We searched CENTRAL, MEDLINE, Embase, and two other databases on 21st November 2019. We also contacted experts in the field and searched references of trials for any additional trials. SELECTION CRITERIA Randomised controlled trials investigating the effectiveness and safety of iron administration interventions compared to other iron administration interventions or placebo in the treatment of iron deficiency anaemia in inflammatory bowel disease. We considered both adults and children, with studies reporting outcomes of clinical, endoscopic, histologic or surgical remission as defined by study authors. DATA COLLECTION AND ANALYSIS Two review authors independently conducted data extraction and 'Risk of bias' assessment of included studies. We expressed dichotomous and continuous outcomes as risk ratios and mean differences with 95% confidence intervals. We assessed the certainty of the evidence using the GRADE methodology. MAIN RESULTS We included 11 studies (1670 randomised participants) that met the inclusion criteria. The studies compared intravenous iron sucrose vs oral iron sulphate (2 studies); oral iron sulphate vs oral iron hydroxide polymaltose complex (1 study); oral iron fumarate vs intravenous iron sucrose (1 study); intravenous ferric carboxymaltose vs intravenous iron sucrose (1 study); erythropoietin injection + intravenous iron sucrose vs intravenous iron sucrose + injection placebo (1 study); oral ferric maltol vs oral placebo (1 study); oral ferric maltol vs intravenous ferric carboxymaltose (1 study); intravenous ferric carboxymaltose vs oral iron sulphate (1 study); intravenous iron isomaltoside vs oral iron sulphate (1 study); erythropoietin injection vs oral placebo (1 study). All studies compared participants with CD and UC together, as well as considering a range of disease activity states. The primary outcome of number of responders, when defined, was stated to be an increase in haemoglobin of 20 g/L in all but two studies in which an increase in 10g/L was used. In one study comparing intravenous ferric carboxymaltose and intravenous iron sucrose, moderate-certainty evidence was found that intravenous ferric carboxymaltose was probably superior to intravenous iron sucrose, although there were responders in both groups (150/244 versus 118/239, RR 1.25, 95% CI 1.06 to 1.46, number needed to treat for an additional beneficial outcome (NNTB) = 9). In one study comparing oral ferric maltol to placebo, there was low-certainty evidence of superiority of the iron (36/64 versus 0/64, RR 73.00, 95% CI 4.58 to 1164.36). There were no other direct comparisons that found any difference in the primary outcomes, although certainty was low and very low for all outcomes, due to imprecision from sparse data and risk of bias varying between moderate and high risk. The reporting of secondary outcomes was inconsistent. The most common was the occurrence of serious adverse events or those requiring withdrawal of therapy. In no comparisons was there a difference seen between any of the intervention agents being studied, although the certainty was very low for all comparisons made, due to risk of bias and significant imprecision due to the low numbers of events. Time to remission, histological and biochemical outcomes were sparsely reported in the studies. None of the other secondary outcomes were reported in any of the studies. An analysis of all intravenous iron preparations to all oral iron preparations showed that intravenous administration may lead to more responders (368/554 versus 205/373, RR 1.17, 95% CI 1.05 to 1.31, NNTB = 11, low-certainty due to risk of bias and inconsistency). Withdrawals due to adverse events may be greater in oral iron preparations vs intravenous (15/554 versus 31/373, RR 0.39, 95% CI 0.20 to 0.74, low-certainty due to risk of bias, inconsistency and imprecision). AUTHORS' CONCLUSIONS Intravenous ferric carboxymaltose probably leads to more people having resolution of IDA (iron deficiency anaemia) than intravenous iron sucrose. Oral ferric maltol may lead to more people having resolution of IDA than placebo. We are unable to draw conclusions on which of the other treatments is most effective in IDA with IBD (inflammatory bowel disease) due to low numbers of studies in each comparison area and clinical heterogeneity within the studies. Therefore, there are no other conclusions regarding the treatments that can be made and certainty of all findings are low or very low. Overall, intravenous iron delivery probably leads to greater response in patients compared with oral iron, with a NNTB (number needed to treat) of 11. Whilst no serious adverse events were specifically elicited with any of the treatments studied, the numbers of reported events were low and the certainty of these findings very low for all comparisons, so no conclusions can be drawn. There may be more withdrawals due to such events when oral is compared with intravenous iron delivery. Other outcomes were poorly reported and once again no conclusions can be made as to the impact of IDA on any of these outcomes. Given the widespread use of many of these treatments in practice and the only guideline that exists recommending the use of intravenous iron in favour of oral iron, research to investigate this key issue is clearly needed. Considering the current ongoing trials identified in this review, these are more focussed on the impact in specific patient groups (young people) or on other symptoms (such as fatigue). Therefore, there is a need for studies to be performed to fill this evidence gap.
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A Systematic Review and Meta-analysis of Paediatric Inflammatory Bowel Disease Incidence and Prevalence Across Europe.
Roberts, SE, Thorne, K, Thapar, N, Broekaert, I, Benninga, MA, Dolinsek, J, Mas, E, Miele, E, Orel, R, Pienar, C, et al
Journal of Crohn's & colitis. 2020;(8):1119-1148
Abstract
BACKGROUND AND AIMS Inflammatory bowel disease [IBD] is often one of the most devastating and debilitating chronic gastrointestinal disorders in children and adolescents. The main objectives here were to systematically review the incidence and prevalence of paediatric IBD across all 51 European states. METHODS We undertook a systematic review and meta-analysis based on PubMed, CINAHL, the Cochrane Library, searches of reference lists, grey literature and websites, covering the period from 1970 to 2018. RESULTS Incidence rates for both paediatric Crohn's disease [CD] and ulcerative colitis [UC] were higher in northern Europe than in other European regions. There have been large increases in the incidence of both paediatric CD and UC over the last 50 years, which appear widespread across Europe. The largest increases for CD have been reported from Sweden, Wales, England, the Czech Republic, Denmark and Hungary, and for UC from the Czech Republic, Ireland, Sweden and Hungary. Incidence rates for paediatric CD have increased up to 9 or 10 per 100 000 population in parts of Europe, including Scandinavia, while rates for paediatric UC are often slightly lower than for CD. Prevalence reported for CD ranged from 8.2 per 100 000 to approximately 60 and, for UC, from 8.3 to approximately 30. CONCLUSIONS The incidence of paediatric IBD continues to increase throughout Europe. There is stronger evidence of a north-south than an east-west gradient in incidence across Europe. Further prospective studies are needed, preferably multinational and based on IBD registries, using standardized definitions, methodology and timescales.
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Systematic review with meta-analysis of partial enteral nutrition for the maintenance of remission in Crohn's disease.
Yang, H, Feng, R, Li, T, Xu, S, Hao, X, Qiu, Y, Chen, M
Nutrition research (New York, N.Y.). 2020;:7-18
Abstract
Although enteral nutrition (EN) is effective for induction therapy in Crohn's disease (CD), it remains unclear whether partial enteral nutrition (PEN), i.e., EN, along with a daily diet, is effective for maintenance therapy in CD. It was hypothesized that PEN would be effective as a maintenance therapy in CD. This meta-analysis aimed to evaluate the efficacy and safety of PEN for maintenance therapy in CD. PubMed, EMBASE, Web of Science, and Cochrane Library were searched up to January 2019 for eligible prospective controlled trials, and then a meta-analysis was conducted. The primary outcome was clinical relapse, as defined in the primary studies. Eight studies with 429 patients were included in the meta-analysis. The rate of clinical relapse at 0.5 to 2 years was significantly lower in patients receiving PEN (420-1800 kcal/d) than in those not receiving nutrition therapy (RR: 0.67, 95% CI: 0.54-0.82, P < .01; number needed to treat = 5, P < .01). Patients receiving PEN exhibited a higher frequency of clinical remission maintenance at 0.5 to 1 year (67%) than did those not receiving nutrition therapy (48%; RR: 1.32, 95% CI: 1.07-1.64, P = .01). The total adverse event rate was comparable in the two groups (RR: 3.60, 95% CI: 0.70-18.66, P = .13). PEN may be more effective than the absence of EN therapy for the maintenance of remission in CD with a good safety profile.
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Diet Therapy for Inflammatory Bowel Diseases: A Call to the Dining Table.
Limketkai, BN, Gordon, M, Mutlu, EA, De Silva, PS, Lewis, JD
Inflammatory bowel diseases. 2020;(4):510-514
Abstract
There is vigorous interest among patients, caregivers, clinicians, and scientists to identify useful dietary interventions for inflammatory bowel diseases (IBD). Through the Cochrane Collaboration, we recently performed a systematic review and meta-analysis of dietary interventions for the induction or maintenance of remission in Crohn's disease (CD) and ulcerative colitis (UC) to assess the latest state of research. The current quality of evidence was formally graded to be low or very low for various methodological reasons, such as small sample sizes, heterogeneity among studies, and incomplete reporting. There are nonetheless emerging observational studies that progressively advance our knowledge and provide hope for a role of diet among traditional therapies to improve inflammation and symptoms. Further investments and concerted efforts in research are needed to significantly move the needle in identifying effective dietary therapies for IBD.
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Efficacy of enteral nutrition in patients with Crohn's disease on maintenance anti-TNF-alpha antibody therapy: a meta-analysis.
Hirai, F, Takeda, T, Takada, Y, Kishi, M, Beppu, T, Takatsu, N, Miyaoka, M, Hisabe, T, Yao, K, Ueki, T
Journal of gastroenterology. 2020;(2):133-141
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Abstract
Enteral nutrition (EN) is effective in Crohn's disease (CD) patients and has been shown to have an inhibitory effect on loss of response to anti-tumor necrosis factor (TNF)-alpha antibody therapy; however, the current level of evidence is not sufficient. The objective of this meta-analysis was to determine whether EN in combination anti-TNF-alpha antibody therapy is useful in maintaining remission. PubMed was used to identify all relevant studies. A total of nine articles were identified including one randomized control trial, two prospective cohort studies, and six retrospective cohort studies. We performed a meta-analysis on all these articles to assess the remission maintenance effect of EN (n = 857). The remission or response maintenance effect in the EN group was 203/288 (70.5%), which was higher than 306/569 (53.8%) in the non-EN group. The odds ratio for long-term remission or response using fixed effects model and random effects model were 2.23 (95% CI 1.60-3.10) and 2.19 (95% CI 1.49-3.22), respectively. The usefulness of EN was unclear in two prospective studies that were conducted immediately after remission induction with anti-TNF-alpha antibody therapy was detected. Differences in the definition of relapse and the observation period among articles were considered to be limitations. This analysis suggests that EN is effective for maintaining remission in patients already in remission or response as a result of anti-TNF-alpha antibody maintenance therapy.
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Exclusive enteral nutrition versus corticosteroids for treatment of pediatric Crohn's disease: a meta-analysis.
Yu, Y, Chen, KC, Chen, J
World journal of pediatrics : WJP. 2019;(1):26-36
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BACKGROUND Many studies have examined the effects of exclusive enteral nutrition (EEN) in children with Crohn's disease (CD), but corticosteroids are considered a superior therapy and are frequently used in China. This meta-analysis aims to compare the efficacy of EEN with corticosteroids in treating pediatric CD. METHODS A comprehensive retrieval from medical databases, including PubMed, EMBASE, MEDLINE, Web of Science, Wanfang data, VIP and CNKI, was performed using the search terms "diet therapy", "exclusive enteral nutrition", "Crohn's disease", "inflammatory bowel diseases", "child" and "pediatrics" from January 1990 to April 2017. RESULTS We included 18 studies from 1329 identified sources in this meta-analysis. EEN was as effective as corticosteroids in inducing remission rate of children suffering from CD (OR = 1.35; 95% CI 0.90, 2.10; P = 0.14). Nevertheless, patients who received EEN were more likely to achieve both endoscopic mucosal healing (OR = 5.24; 95% CI 2.06, 13.37; P = 0.0005) and histological mucosal healing (OR = 4.78; 95% CI 1.89, 12.08; P = 0.0009) than those who received corticosteroids; the Pediatric Crohn's Disease Activity Index was lower [mean difference (MD) = - 3.67; 95% CI - 4.91, - 2.43] and weight gain was higher (MD = 1.92; 95% CI 0.02, 3.83; P = 0.05) in those patients who received EEN than in those who received corticosteroids. No difference was found in relapse rate (OR = 0.57; 95% CI 0.25, 1.29; P = 0.18), height for age or body mass index between the patients treated with EEN and corticosteroids at the 1-year end point. CONCLUSIONS This meta-analysis reveals that there is no significant difference between EEN and corticosteroids in the efficacy of inducing remission rate of CD in a pediatric population, but EEN is superior to corticosteroids in improving short-term mucosal inflammation and reducing the PCDAI index.
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Efficacy of Endoscopic Dilation of Gastroduodenal Crohn's Disease Strictures: A Systematic Review and Meta-Analysis of Individual Patient Data.
Bettenworth, D, Mücke, MM, Lopez, R, Singh, A, Zhu, W, Guo, F, Matsui, T, James, TW, Herfarth, H, Goetz, M, et al
Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association. 2019;(12):2514-2522.e8
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BACKGROUND & AIMS Little is known about the effects of endoscopic balloon dilation (EBD) for strictures of the upper gastrointestinal (UGI) tract in patients with Crohn's disease (CD). We performed a pooled analysis of the efficacy and safety of EBD for UGI CD-associated strictures. METHODS We searched Embase, Medline, and the Cochrane library, as well as bibliographies of relevant articles, for cohort studies of adults with CD and strictures of the stomach or duodenum (up to the ligament of Treitz) who underwent EBD through December 2016. We obtained data from 7 international referral centers on 94 patients who underwent 141 EBDs. We performed a patient-level meta-analysis of data from published and unpublished cohort studies to determine mechanical and clinical success. We performed a time-to-event analysis to assess symptom recurrence and need for redilation or surgery. The patients analyzed had strictures of the duodenum (n = 107), stomach (n = 30), or spanning both (n = 4). RESULTS The rate of technical success for EBD was 100%, with 87% short-term clinical efficacy; major complications arose from 2.9% of all procedures. During a median follow-up period of 23.1 months, 70.5% of patients had a recurrence of symptoms, 59.6% required redilation, and 30.8% required surgical intervention. Patients whose disease was located in the small bowel had a higher risk for symptom recurrence (hazard ratio [HR], 2.1; P = .003). Asian race (HR, 2.8; P < .001) and location of disease in the small bowel (HR, 1.9; P = .004) increased the need for redilation. Prestenotic dilation was a risk factor for needing surgery earlier (HR, 1.9; P = .001). CONCLUSIONS In a meta-analysis, we found EBD for CD-associated strictures of the UGI to be an effective alternative to surgery, with a high rate of short-term technical and clinical success, moderate long-term efficacy, and an acceptable rate of complications.
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Enteral nutritional therapy for induction of remission in Crohn's disease.
Narula, N, Dhillon, A, Zhang, D, Sherlock, ME, Tondeur, M, Zachos, M
The Cochrane database of systematic reviews. 2018;(4):CD000542
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BACKGROUND Corticosteroids are often preferred over enteral nutrition (EN) as induction therapy for Crohn's disease (CD). Prior meta-analyses suggest that corticosteroids are superior to EN for induction of remission in CD. Treatment failures in EN trials are often due to poor compliance, with dropouts frequently due to poor acceptance of a nasogastric tube and unpalatable formulations. This systematic review is an update of a previously published Cochrane review. OBJECTIVES To evaluate the effectiveness and safety of exclusive EN as primary therapy to induce remission in CD and to examine the importance of formula composition on effectiveness. SEARCH METHODS We searched MEDLINE, Embase and CENTRAL from inception to 5 July 2017. We also searched references of retrieved articles and conference abstracts. SELECTION CRITERIA Randomized controlled trials involving patients with active CD were considered for inclusion. Studies comparing one type of EN to another type of EN or conventional corticosteroids were selected for review. DATA COLLECTION AND ANALYSIS Data were extracted independently by at least two authors. The primary outcome was clinical remission. Secondary outcomes included adverse events, serious adverse events and withdrawal due to adverse events. For dichotomous outcomes, we calculated the risk ratio (RR) and 95% confidence interval (CI). A random-effects model was used to pool data. We performed intention-to-treat and per-protocol analyses for the primary outcome. Heterogeneity was explored using the Chi2 and I2 statistics. The studies were separated into two comparisons: one EN formulation compared to another EN formulation and EN compared to corticosteroids. Subgroup analyses were based on formula composition and age. Sensitivity analyses included abstract publications and poor quality studies. We used the Cochrane risk of bias tool to assess study quality. We used the GRADE criteria to assess the overall quality of the evidence supporting the primary outcome and selected secondary outcomes. MAIN RESULTS Twenty-seven studies (1,011 participants) were included. Three studies were rated as low risk of bias. Seven studies were rated as high risk of bias and 17 were rated as unclear risk of bias due to insufficient information. Seventeen trials compared different formulations of EN, 13 studies compared one or more elemental formulas to a non-elemental formula, three studies compared EN diets of similar protein composition but different fat composition, and one study compared non-elemental diets differing in glutamine enrichment. Meta-analysis of 11 trials (378 participants) demonstrated no difference in remission rates. Sixty-four per cent (134/210) of patients in the elemental group achieved remission compared to 62% (105/168) of patients in the non-elemental group (RR 1.02, 95% CI 0.88 to 1.18; GRADE very low quality). A per-protocol analysis (346 participants) produced similar results (RR 1.04, 95% CI 0.91 to 1.18). Subgroup analyses performed to evaluate the different types of elemental and non-elemental diets (elemental, semi-elemental and polymeric) showed no differences in remission rates. An analysis of 7 trials including 209 patients treated with EN formulas of differing fat content (low fat: < 20 g/1000 kCal versus high fat: > 20 g/1000 kCal) demonstrated no difference in remission rates (RR 1.03; 95% CI 0.85 to 1.26). Very low fat content (< 3 g/1000 kCal) and very low long chain triglycerides demonstrated higher remission rates than higher content EN formulas. There was no difference between elemental and non-elemental diets in adverse event rates (RR 1.00, 95% CI 0.63 to 1.60; GRADE very low quality), or withdrawals due to adverse events (RR 1.29, 95% CI 0.80 to 2.09; GRADE very low quality). Common adverse events included nausea, vomiting, diarrhea and bloating.Ten trials compared EN to steroid therapy. Meta-analysis of eight trials (223 participants) demonstrated no difference in remission rates between EN and steroids. Fifty per cent (111/223) of patients in the EN group achieved remission compared to 72% (133/186) of patients in the steroid group (RR 0.77, 95% CI 0.58 to 1.03; GRADE very low quality). Subgroup analysis by age showed a difference in remission rates for adults but not for children. In adults 45% (87/194) of EN patients achieved remission compared to 73% (116/158) of steroid patients (RR 0.65, 95% CI 0.52 to 0.82; GRADE very low quality). In children, 83% (24/29) of EN patients achieved remission compared to 61% (17/28) of steroid patients (RR 1.35, 95% CI 0.92 to 1.97; GRADE very low quality). A per-protocol analysis produced similar results (RR 0.93, 95% CI 0.75 to 1.14). The per-protocol subgroup analysis showed a difference in remission rates for both adults (RR 0.82, 95% CI 0.70 to 0.95) and children (RR 1.43, 95% CI 1.03 to 1.97). There was no difference in adverse event rates (RR 1.39, 95% CI 0.62 to 3.11; GRADE very low quality). However, patients on EN were more likely to withdraw due to adverse events than those on steroid therapy (RR 2.95, 95% CI 1.02 to 8.48; GRADE very low quality). Common adverse events reported in the EN group included heartburn, flatulence, diarrhea and vomiting, and for steroid therapy acne, moon facies, hyperglycemia, muscle weakness and hypoglycemia. The most common reason for withdrawal was inability to tolerate the EN diet. AUTHORS' CONCLUSIONS Very low quality evidence suggests that corticosteroid therapy may be more effective than EN for induction of clinical remission in adults with active CD. Very low quality evidence also suggests that EN may be more effective than steroids for induction of remission in children with active CD. Protein composition does not appear to influence the effectiveness of EN for the treatment of active CD. EN should be considered in pediatric CD patients or in adult patients who can comply with nasogastric tube feeding or perceive the formulations to be palatable, or when steroid side effects are not tolerated or better avoided. Further research is required to confirm the superiority of corticosteroids over EN in adults. Further research is required to confirm the benefit of EN in children. More effort from industry should be taken to develop palatable polymeric formulations that can be delivered without use of a nasogastric tube as this may lead to increased patient adherence with this therapy.
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Protective association of TNFSF15 polymorphisms with Crohn's disease and ulcerative colitis: A meta-analysis.
He, L, Chen, J, Sun, J, Peng, J, He, Q
Saudi journal of gastroenterology : official journal of the Saudi Gastroenterology Association. 2018;(4):201-210
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Abstract
BACKGROUND/AIMS: Three extensively investigated polymorphisms (rs3810936, rs7848647, and rs6478108) in tumor necrosis factor super family member 15 (TNFSF15) gene have been implicated in risk for inflammatory bowel disease (IBD). We performed a quantitative synthesis of the evidence to clarify these associations of TNFSF15 polymorphisms with IBD. MATERIALS AND METHODS Data were extracted from PubMed and EMBASE, up to March 15, 2018. Meta-analysis was performed by critically reviewing five studies for rs3810936 polymorphism (2251 cases and 2442 controls), four studies for rs7848647 polymorphism (1503 cases and 1816 controls), and four studies for rs6478108 polymorphism (1502 cases and 1817 controls). RESULTS Our analysis suggested that rs3810936 polymorphism was significantly associated with decreased risk of Crohn's disease (CD) and ulcerative colitis (UC). For rs7848647 polymorphism, significantly protective association between this polymorphism and CD risk was also observed, but not in UC. For rs6478108 polymorphism, we also detected a significantly protective association with CD risk in all genetic model but not in UC. CONCLUSIONS This meta-analysis suggests that TNFSF15 polymorphisms may contribute to genetic susceptibility of IBD.
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Genome-Wide Association Study Identifies African-Specific Susceptibility Loci in African Americans With Inflammatory Bowel Disease.
Brant, SR, Okou, DT, Simpson, CL, Cutler, DJ, Haritunians, T, Bradfield, JP, Chopra, P, Prince, J, Begum, F, Kumar, A, et al
Gastroenterology. 2017;(1):206-217.e2
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BACKGROUND & AIMS The inflammatory bowel diseases (IBD) ulcerative colitis (UC) and Crohn's disease (CD) cause significant morbidity and are increasing in prevalence among all populations, including African Americans. More than 200 susceptibility loci have been identified in populations of predominantly European ancestry, but few loci have been associated with IBD in other ethnicities. METHODS We performed 2 high-density, genome-wide scans comprising 2345 cases of African Americans with IBD (1646 with CD, 583 with UC, and 116 inflammatory bowel disease unclassified) and 5002 individuals without IBD (controls, identified from the Health Retirement Study and Kaiser Permanente database). Single-nucleotide polymorphisms (SNPs) associated at P < 5.0 × 10-8 in meta-analysis with a nominal evidence (P < .05) in each scan were considered to have genome-wide significance. RESULTS We detected SNPs at HLA-DRB1, and African-specific SNPs at ZNF649 and LSAMP, with associations of genome-wide significance for UC. We detected SNPs at USP25 with associations of genome-wide significance for IBD. No associations of genome-wide significance were detected for CD. In addition, 9 genes previously associated with IBD contained SNPs with significant evidence for replication (P < 1.6 × 10-6): ADCY3, CXCR6, HLA-DRB1 to HLA-DQA1 (genome-wide significance on conditioning), IL12B,PTGER4, and TNC for IBD; IL23R, PTGER4, and SNX20 (in strong linkage disequilibrium with NOD2) for CD; and KCNQ2 (near TNFRSF6B) for UC. Several of these genes, such as TNC (near TNFSF15), CXCR6, and genes associated with IBD at the HLA locus, contained SNPs with unique association patterns with African-specific alleles. CONCLUSIONS We performed a genome-wide association study of African Americans with IBD and identified loci associated with UC in only this population; we also replicated IBD, CD, and UC loci identified in European populations. The detection of variants associated with IBD risk in only people of African descent demonstrates the importance of studying the genetics of IBD and other complex diseases in populations beyond those of European ancestry.