Crohn's disease runs a more aggressive course in young Asian patients

A Systematic Review on the Increasing Incidence of Inflammatory Bowel Disease in Southeast Asia: Looking Beyond the Urbanization Phenomenon

The incidence of inflammatory bowel disease (IBD) has been increasing in Southeast Asia (SEA) in tandem with its economic growth and urbanization over the past 2 decades. Specific characteristics of IBD in SEA are similar to East Asia and the West, such as the declining ratio of ulcerative colitis to Crohn's disease. However, exceptionally low familial aggregation is seen. Smoking is also not a common risk factor in patients with Crohn's disease. The incidence of perianal disease is higher in SEA than in Australia and is comparable to the West. In a multiracial population, such as Singapore and Malaysia, Indians have the highest incidence and prevalence rates, which are likely to be due to important putative mutations. For instance, a higher frequency of the NOD2 predisposing mutation SNP5 and IBD risk allele IGR2198a and IGR2092a were found in Indians. Although differences in the genetic constitution play an important role in the epidemiology and prognosis of IBD in SEA, the emergence of this disease offers a unique opportunity to identify potential exposomes that contribute to its pathogenesis.

What Are the Different Phenotypes of Inflammatory Bowel Disease in Asia?

The burden of inflammatory bowel disease (IBD) in Asia has been increasing over the past decades. Although patients with IBD show heterogenous phenotypes depending on the individual characteristics, no significant differences have been established in the IBD phenotypes of Western and Asian populations. However, despite the much lower incidence of IBD in Asia than in Western countries, the incidence has been rapidly increasing in Asia while remaining stable in Western countries. The incidence of ulcerative colitis (UC) showed an earlier and a more marked increase than the incidence of Crohn disease (CD), but the UC-to-CD ratio has recently decreased because of a relative increase in the incidence of CD in Asia. While CD shows a significant male predominance, UC only shows a slight male predominance. A recent study reported that the incidence of IBD in Asia showed a bimodal age distribution with increasing IBD prevalence, similar to the findings of Western studies. CD in Asian patients, especially those in East Asia, is characterized by ileocolonic involvement and perianal fistula. The frequency of extraintestinal manifestations, including primary sclerosing cholangitis, appears to be lower in Asia, but this finding should be interpreted with caution due to the transient and nonspecific nature of these manifestations. Although familial aggregation is lower in East Asia, it may also be explained by the low prevalence of IBD in Asia. Thus, more studies should focus on the differences in phenotypes in Asian IBD patients versus Western patients.

Risk Factors for Postoperative Recurrence in Korean Patients with Crohn's Disease

Background/Aims

A considerable number of patients with Crohn’s disease still need intestinal resection surgery. Postoperative recurrence is an important issue in Crohn’s disease management, including the selection of high-risk patients. Eastern Asian patients showed several differences from Caucasian patients. Therefore, we investigated the postoperative surgical recurrence outcome and identified risk factors in Korean patients.

Methods

Clinical data of 372 patients with Crohn’s disease who underwent first intestinal resection between January 2004 and August 2014 at 14 hospitals in Korea were retrospectively reviewed.

Results

Over the follow-up period, 50 patients (17.1%) showed surgical recurrence. The cumulative surgical recurrence rate was 6.5% at 1 year and 15.4% at 7 years. Age under 16 (p=0.011; hazard ratio [HR], 5.136; 95% confidence interval [CI], 1.576 to 16.731), colonic involvement (p=0.023; HR , 2.011; 95% CI, 1.102 to 3.670), and the presence of perianal disease at surgery (p=0.008; HR, 2.239; 95% CI, 1.236 to 4.059) were independent risk factors associated with surgical recurrence. Postoperative thiopurine treatment (p=0.002; HR, 0.393; 95% CI, 0.218 to 0.710) was a protective factor for surgical recurrence.

Conclusions

Among the disease characteristics at surgery, younger age, colonic location, and perianal lesions were independent risk factors for surgical recurrence. Postoperative thiopurine treatment significantly reduced the incidence of surgical recurrence.

Genetic Studies of Inflammatory Bowel Disease-Focusing on Asian Patients

The pathogenesis of inflammatory bowel disease (IBD) is not well-understood; however, increased and persistent intestinal inflammation, due to inappropriate immune responses that are caused by interactions between genetic factors, gut microbiota, and environmental factors, are thought to lead to IBD. Various studies have identified more than 240 genetic variants related to IBD. These genetic variants are involved in innate and adaptive immunity, autophagy, defective bacterial handing, interleukin-23 and 10 signaling, and so on. According to several epidemiological and clinical studies, the phenotypes and clinical course of IBD differ between Asians and Europeans. Although the risk loci for IBD typically overlap between Asians and Westerners, genetic heterogeneity has been detected in many loci/genes, such as NOD2/CARD15, TNFSF15 and human leukocyte antigen, contributing to the risk of IBD. Thus, although common pathways exist between Westerners and Asians in the development of IBD, their significance may differ for individual pathways. Although genetic studies are not universally applicable in the clinical field, they may be useful for diagnosing and categorizing IBD, predicting therapeutic responses and toxicity to drugs, and assessing prognosis by risk modeling, thereby enabling precision medicine for individual patients.

Epidemiology of Inflammatory Bowel Disease in India: The Great Shift East

BACKGROUND

Inflammatory bowel disease (IBD), once considered to be a Western disease, is increasingly being reported from India and other Asian countries. The present review summarizes epidemiology and disease characteristics of IBD in India with reference to other Asian countries and the West.

SUMMARY

India is projected to have one of the highest disease burden of IBD across the globe. The overall genetic risk and microbial signature in Indian IBD patients are similar to those of patients in the West as demonstrated by the similar incidence of IBD in second-generation Indian immigrants and matching perturbations in the structural and functional component of gut microbiota in Indian studies. The concept of the hygiene hypothesis continues to remain controversial with Indian studies demonstrating contradictory findings. The disease characteristics, long-term outcomes including the risk of colorectal cancer, and the effect of pregnancy on IBD and vice versa in Indian patients with IBD are in general similar with few differences. Unlike patients in the West, very few Indian patients have a positive family history.

KEY MESSAGE

The Indian disease pattern is going through a phase of epidemiological transition with a surge in the incidence of IBD. The epidemiology and disease characteristics of IBD mirror the patterns observed in the West.

Risk Genes of Inflammatory Bowel Disease in Asia: What Are the Most Important Pathways Affected?

Genetic factors play an important role in the pathogenesis of inflammatory bowel disease (IBD), and IBD is now recognized as a complex disease that results from interplay between genetic and environment factors. To date, over 160 IBD-susceptible loci have been identified using genome-wide association studies (GWAS). The risk genes identified in these studies are involved in various pathways in innate and adaptive immune response such as innate bacterial sensing, autophagy and interleukin-23 receptor/T-helper cell 17 pathway. It was initially believed that the genetic backgrounds of Asian IBD patients differ from that of other populations. Recent GWAS and meta-analysis found that there is pervasive sharing of risk loci between the East and West. Overlapping risk genes between populations of different ancestries indicate that pathways underlying the etiology of IBD may be common between Asia and other areas. However, the importance of individual pathways may be different in Asia from the Western countries. Identifying the most important pathways affected in Asian IBD patients may provide a better understanding of pathogenesis of IBD in Asia and improve the clinical management of the patients.

Asia Pacific Consensus Statements on Crohn's disease. Part 1: Definition, diagnosis, and epidemiology: (Asia Pacific Crohn's Disease Consensus--Part 1)

Inflammatory bowel disease (IBD) was previously thought to be rare in Asia, but emerging data indicate rising incidence and prevalence of IBD in the region. The Asia Pacific Working Group on Inflammatory Bowel Disease was established in Cebu, Philippines, at the Asia Pacific Digestive Week conference in 2006 under the auspices of the Asian Pacific Association of Gastroenterology with the goal of developing best management practices, coordinating research, and raising awareness of IBD in the region. The consensus group previously published recommendations for the diagnosis and management of ulcerative colitis with specific relevance to the Asia-Pacific region. The present consensus statements were developed following a similar process to address the epidemiology, diagnosis, and management of Crohn's disease. The goals of these statements are to pool the pertinent literature specifically highlighting relevant data and conditions in the Asia-Pacific region relating to the economy, health systems, background infectious diseases, differential diagnoses, and treatment availability. It does not intend to be all comprehensive and future revisions are likely to be required in this ever-changing field.

Risk of Major Abdominal Surgery in an Asian Population-based Crohn's Disease Cohort

BACKGROUND

Crohn's disease (CD) is increasing in incidence and prevalence in Asia, but there is a paucity of population-based studies on risk factors for surgery in Asian patients with CD. This will be useful to identify patients who may benefit from top-down treatment. This study describes the rates of abdominal surgery and identifies associated risk factors in Singaporean patients with CD.

METHODS

This was a retrospective observational study. The medical records of Singaporeans diagnosed with CD from 1970 to 2013 were reviewed from 8 different hospitals in Singapore. The cumulative probability of CD-related abdominal surgery was estimated using the Kaplan-Meier method. The logistic regression model was used to assess associations between independent risk factors and surgery.

RESULTS

The cohort of 430 Singaporean patients with CD included 63.5% Chinese, 11.9% Malay, and 24.7% Indians, with a male to female ratio of 1.6; median follow-up was 7.3 years (range, 2.9-13.0 yr) and median age at diagnosis 30.5 years (range, 19.5-43.7 yr). One hundred twelve patients (26.0%) required major abdominal surgery: the cumulative risk of surgery was 14.9% at 90 days, 21.2% at 5 years, 28.8% at 10 years, 38.3% at 20 years, and 50.6% at 30 years from diagnosis. Of the surgical patients, 75.0% were Chinese, 10.7% Malays, and 14.3% Indians; 21.4% underwent surgery for inflammatory disease, 40.2% for stricturing disease, and 38.4% for penetrating disease. Age at diagnosis (A2 17-40 yr, OR: 2.75, 95% confidence interval [CI], 1.14-7.76), ileal disease (L1 location, OR: 2.35, 95% CI, 1.14-5.0), stricturing (B2 OR: 6.09, 95% CI, 3.20-11.8), and penetrating behavior (B3 OR: 21.6, 95% CI, 9.0-58.8) were independent risk factors for CD-related abdominal surgery. Indian patients were less likely to require surgery (OR: 0.40, 95% CI, 0.19-0.78).

CONCLUSIONS

Age at diagnosis, L1 location, B2, and B3 disease behavior are independent risk factors for abdominal surgery. Interestingly, despite a higher prevalence of CD in Indians, a smaller proportion of Indian patients required surgery. These findings suggest that both environmental and genetic factors contribute to the risk of surgery in Asian patients with CD.

A first study on the incidence and prevalence of IBD in Malaysia--results from the Kinta Valley IBD Epidemiology Study

BACKGROUND

Inflammatory bowel disease [IBD] is known to be rare in the Asia Pacific region but epidemiological studies are scarce.

METHODS

Kinta Valley [Ipoh] was chosen as the sample population. Malaysia has a multiethnic population consisting of Malays, Chinese, and Indians. New cases over 2 years were prospectively captured as well as all known existing cases. Total numbers of the population as a whole and of each ethnic group were obtained. Incidence, prevalence, and mean incidence over two decades were then calculated.

RESULTS

There were 10 new cases of IBD diagnosed from April 2011 to April 2013. The crude incidence rates of IBD, ulcerative colitis [UC], and Crohn's disease[CD], respectively, were 0.68, 0.46, and 0.20 per 100,000 persons. The highest incidence was among the Indians, 1.91 compared with 0.35 and 0.63 per 100,000 persons among the Malays and the Chinese, respectively. The mean incidence of IBD has increased steadily from 0.07 to 0.69 per 100,000 person-years over the past two decades. The UC:CD ratio was 8:1 from 1990 to 2000 and 3.6:1 from 2000 to 2010. The prevalence rates of IBD, UC, and CD, respectively, were 9.24, 6.67, and 2.17 per 100,000 persons. The highest prevalence also was among the Indians: 24.91 compared with 7.00 and 6.90 per 100,000 persons among the Malay and Chinese races, respectively.

CONCLUSIONS

The incidence and prevalence rates of IBD are low in Malaysia but the incidence appears to be increasing and marked racial differences exist. As in other Asian countries, the incidence of CD is increasing at a more rapid rate relative to UC.

Clinical characteristics and treatment of inflammatory bowel disease: A comparison of Eastern and Western perspectives

Inflammatory bowel disease (IBD) is a chronic, relapsing intestinal inflammatory disorder with unidentified causes. Both environmental factors and genetic aspects are believed to be crucial to the pathogenesis of IBD. The incidence and prevalence of IBD have recently been increasing throughout Asia, presumably secondary to environmental changes. This increasing trend in IBD epidemiology necessitates specific health care planning and education in Asia. To this end, we must gain a precise understanding of the distinctive clinical and therapeutic characteristics of Asian patients with IBD. The phenotypes of IBD reportedly differ considerably between Asians and Caucasians. Thus, use of the same management strategies for these different populations may not be appropriate. Moreover, investigation of the Asian-specific clinical aspects of IBD offers the possibility of identifying causative factors in the pathogenesis of IBD in this geographical area. Accordingly, this review summarizes current knowledge of the phenotypic manifestations and management practices of patients with IBD, with a special focus on a comparison of Eastern and Western perspectives.

The association between race and Crohn's disease phenotype in the Western Cape population of South Africa, defined by the Montreal Classification System

BACKGROUND

Inter-racial differences in disease characteristics and in the management of Crohn's disease (CD) have been described in African American and Asian subjects, however for the racial groups in South Africa, no such recent literature exists.

METHODS

A cross sectional study of all consecutive CD patients seen at 2 large inflammatory bowel disease (IBD) referral centers in the Western Cape, South Africa between September 2011 and January 2013 was performed. Numerous demographic and clinical variables at diagnosis and date of study enrolment were identified using an investigator administered questionnaire as well as clinical examination and patient case notes. Using predefined definitions, disease behavior was stratified as 'complicated' or 'uncomplicated'.

RESULTS

One hundred and ninety four CD subjects were identified; 35 (18%) were white, 152 (78%) were Cape Coloured and 7(4%) were black. On multiple logistic regression analysis Cape Coloureds were significantly more likely to develop 'complicated' CD (60% vs. 9%, p = 0.023) during the disease course when compared to white subjects. In addition, significantly more white subjects had successfully discontinued cigarette smoking at study enrolment (31% vs. 7% reduction, p = 0.02). No additional inter-racial differences were found. A low proportion of IBD family history was observed among the non-white subjects.

CONCLUSIONS

Cape Coloured patients were significantly more likely to develop 'complicated' CD over time when compared to whites.

Inflammatory Bowel Disease-related Colorectal Cancer in the Asia-Pacific Region: Past, Present, and Future

Patients with inflammatory bowel disease (IBD) are at an increased risk of developing colorectal cancer (CRC), and key contributing factors include chronic colonic inflammation and the extent and duration of disease. This increase in risk is more likely to result from chronic inflammation of the colonic mucosa than from any clearly defined genetic predisposition. However, globally, the true magnitude of this risk is debatable, since results from different studies are heterogeneous in terms of geographical and methodological variables. The prevalence of IBD-related CRC in the Asia-Pacific region ranges from 0.3% to 1.8% and a recent study found that the cumulative incidence of IBD-related CRC is comparable to that in Western countries. However, the CRC mortality rate in the Asia-Pacific region is on the rise compared with that in Western countries, and a few Asian countries show particularly rapid upward trends in CRC incidence. Although our understanding of the molecular and clinical basis for IBD-related CRC has improved substantially, our means of prevention, endoscopic surveillance, chemoprevention, and prophylactic surgery remain modest at best. Furthermore, published data on IBD-related CRC in the Asia-Pacific region is lacking, and this review addresses many aspects including epidemiology, natural history, etiopathogenesis, morphology, and biological behaviors of IBD-related CRC and sporadic CRC in the Asia-Pacific region. In this review, we will also discuss the risk factors for CRC in IBD patients, endoscopic technology screening, and surveillance programs and management strategies for IBD-related CRC.

Epidemiology of inflammatory bowel disease: focus on Asia

The epidemiology of inflammatory bowel disease (IBD) is changing globally. Incidence and prevalence may have stabilized in high-incidence areas such as North America and Europe but they continue to rise in previously low-incidence areas such as Eastern Europe, Asia, and much of the developing world. This epidemiological shift likely relates to westernization of lifestyle, changes in diet, and improved hygiene as part of socioeconomic development in developing countries. In Asia, UC is more prevalent than CD, although the UC:CD ratio is narrowing in certain areas. Clinical manifestations of IBD in Asia resemble the Western population, but with some differences, including higher prevalence of males and ileo-colonic CD, less familial clustering, lower surgical rates and extra-intestinal manifestations. These differences may relate to time, genetics and environmental factors. Studying the epidemiology of IBD in an area of rapidly increasing incidence may lead to discovery of important etiologic factors associated with disease development.

Review of inflammatory bowel disease in China

Inflammatory bowel disease mainly consisting of ulcerative colitis and Crohn's disease has been rising gradually during the last two decades in China. In this review article, we provide the latest epidemiological trends in incidence, prevalence, and mortality of IBD patients in China and summarize the risk factors and genetic susceptibility of Chinese IBD patients. We also compare these characteristics to those of IBD patients in Western countries.

Geographical variability and environmental risk factors in inflammatory bowel disease

The changing epidemiology of inflammatory bowel disease (IBD) across time and geography suggests that environmental factors play a major role in modifying disease expression. Disease emergence in developing nations suggests that epidemiological evolution is related to westernisation of lifestyle and industrialisation. The strongest environmental associations identified are cigarette smoking and appendectomy, although neither alone explains the variation in incidence of IBD worldwide. Urbanisation of societies, associated with changes in diet, antibiotic use, hygiene status, microbial exposures and pollution have been implicated as potential environmental risk factors for IBD. Changes in socioeconomic status might occur differently in different geographical areas and populations and, consequently, it is important to consider the heterogeneity of risk factors applicable to the individual patient. Environmental risk factors of individual, familial, community-based, country-based and regionally based origin may all contribute to the pathogenesis of IBD. The geographical variation of IBD provides clues for researchers to investigate possible environmental aetiological factors. The present review aims to provide an update of the literature exploring geographical variability in IBD and to explore the environmental risk factors that may account for this variability.

Risk factors for surgery and postoperative recurrence: analysis of a south China cohort with Crohn's disease

BACKGROUND AND AIMS

To investigate the risk factors for primary surgery and postoperative recurrence in a cohort of Chinese Crohn's disease (CD) patients.

METHODS

Medical notes of consecutive diagnosed patients from 2003 until 2010 were reviewed. Fifty-seven postoperative patients--finished regular follow-up--were recruited for postoperative recurrence analysis.

RESULTS

One hundred eleven of 323 (34.4%) patients of this cohort underwent primary surgery. The cumulative frequency of resection was 16.6%, 35.4%, 53%, and 94.5% for 1, 5, 10, and 30 years, respectively, after onset of disease. Male (OR: 1.994; 95% CI: 1.291-3.078, p = 0.002), stricture (OR: 4.832; 95% CI: 3.064-7.621, p = 0.000), or penetrating (OR: 4.923; 95% CI: 3.060-7.919, p = 0.000) were associated with an increased risk for primary surgery, while early use of immunomodulators was (OR: 0.438; 95% CI: 0.218-0.880, p = 0.020) associated with a decreased risk. Fifty-seven (21.1%) patients were diagnosed as postoperative clinical recurrence and the cumulative recurrence rates were 6.1%, 17.1%, and 36.8% for 1, 2, and 3 years, respectively. Perianal disease was associated with an increased risk for clinical recurrence (OR: 5.606; 95% CI: 1.59-19.766, p = 0.007).

CONCLUSIONS

The operation frequency is high in CD. Male, penetrating, and stricture diseases are associated with an increased risk for primary surgery while early use of immunomodulators is associated with a decreased risk. The postoperative recurrence rate is also high. Patients with perianal disease are at higher risk for clinical recurrence.

Risk factors for repeat abdominal surgery in korean patients with Crohn's disease: a multi-center study of a korean inflammatory bowel disease study group

Purpose

The purpose of this study was to assess the risk factors for repeated abdominal surgery in Crohn's disease (CD) patients after the first abdominal surgery. Prior studies have tried to identify the risk factors for postoperative recurrence in CD patients, but the results of the studies have been inconsistent. Furthermore, few data on the risk factors for repeated abdominal surgery are available.

Methods

Clinical data on CD patients who underwent abdominal surgery from January 2000 to December 2009 were collected from seventeen university hospitals and one colorectal clinic. Data from a total of 708 patients were analyzed to find the risk factors for repeated abdominal surgery in CD patients. The mean follow-up period was 72 months.

Results

The risk of repeated abdominal surgery was 3 times higher in young patients (below 16 years old) than in older patients (odds ratio [OR], 3.056; 95% confidence interval [CI], 1.021 to 9.150); P = 0.046). Stricturing behavior at diagnosis was also a risk factor for repeated abdominal surgery (OR, 2.438; 95% CI, 1.144 to 5.196; P = 0.021). Among operative indications, only intra-abdominal abscess was associated with repeated abdominal surgery (OR, 2.393; 95% CI, 1.098 to 5.216; P = 0.028). Concerning type of operation, an ileostomy might be a risk factor for repeated abdominal surgery (OR, 11.437; 95% CI, 1.451 to 90.124; P = 0.021). Emergency surgery (OR, 4.994; 95% CI, 2.123 to 11.745; P < 0.001) and delayed diagnosis after surgery (OR, 2.339; 95% CI, 1.147 to 4.771; P = 0.019) also increased the risk of repeated abdominal surgery.

Conclusion

Young age (below 16 years), stricturing behavior, intra-abdominal abscess, emergency surgery, and delayed diagnosis after surgery were identified as possible risk factors for repeated abdominal surgery in CD patients.

Inflammatory bowel disease in Asia: a systematic review

The incidence and prevalence of inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC), are lower in Asia than in the West. However, across Asia the incidence and prevalence of IBD has increased rapidly over the last two to four decades. These changes may relate to increased contact with the West, westernization of diet, increasing antibiotics use, improved hygiene, vaccinations, or changes in the gut microbiota. Genetic factors also differ between Asians and the Caucasians. In Asia, UC is more prevalent than CD, although CD incidence is rapidly increasing in certain areas. There is a male predominance of CD in Asia, but a trend towards equal sex distribution for UC. IBD is diagnosed at a slightly older age than in the West, and there is rarely a second incidence peak as in the West. A positive family history is much less common than in the West, as are extra-intestinal disease manifestations. There are clear ethnic differences in incidence within countries in Asia, and an increased incidence in IBD in migrants from Asia to the West. Research in Asia, an area of rapidly changing IBD epidemiology, may lead to the discovery of critical etiologic factors that lead to the development of IBD.

Biologic agent use varies inversely with age at diagnosis in Crohn's disease

BACKGROUND

For patients with Crohn's disease, age at onset is known to influence the clinical course of the illness.

AIMS

The aim of this study is to seek an association between age at onset of Crohn's disease and use of biologic agents for its treatment.

METHODS

We reviewed the medical records of 127 veteran patients with Crohn's disease treated at our hospital, and compared differences in age at disease onset between patients who had received biologics and those who had not.

RESULTS

The mean age of our patients was 54.9 ± 15.4 years, and 34% were currently receiving or had previously received treatment with a biologic agent. For those with biologic use, average age at time of diagnosis of Crohn's disease was 32.3 ± 12.2 years, compared with 43.7 ± 16.3 years for those who had not received biologics (P = 0.005). This relationship remained significant even after controlling for disease severity. The frequency of use of biologic agents varied inversely with age at diagnosis. For patients diagnosed before age 21 years, 55.5% had used biologics, whereas no patient >70 years of age at time of diagnosis had used biologics. We found no significant correlation between biologic use and duration of disease, smoking or ethnicity. Perianal disease and concomitant arthritis were both significantly associated with use of biologics.

CONCLUSIONS

In our veteran patients with Crohn's disease, frequency of treatment with a biologic agent varied inversely with age at disease onset.

Inflammatory bowel disease in the Asia-Pacific area: a comparison with developed countries and regional differences

The Asia-Pacific region has been marked as an area with a low incidence of inflammatory bowel disease (IBD), although confusion always existed as to whether this low incidence was a result of low diagnostic awareness, a high incidence of infective diarrhoea and its diagnostic overlap or a true low incidence. As epidemiological studies from this region are being made available it is clear that the incidence and prevalence rates of IBD in Asia-Pacific region are low compared with Europe and North America. They are however, increasing rapidly. There are substantial variations in the incidence and prevalence rates of IBD in various ethnic groups in Asia. The highest incidence rates are recorded from India, Japan and the Middle East and there exists a genetic predisposition of South Asians (Indians, Pakistanis and Bangladeshis) to ulcerative colitis (UC). It appears that certain racial groups are more prone than others to develop IBD. For instance, Indians in South-East Asia have higher rates than Chinese and Malays. While there is a host genetic predisposition, environmental factor(s) may be responsible for this difference. The clinical phenotypes and complication rates of Asian IBD resemble those of the Caucasian population in general, but some heterogeneity is observed in different regions of Asia. There is no evidence of a north-south or an east-west divide in the Asia-Pacific region. The available studies suggest an increasing incidence of UC in the Asia-Pacific region and hence it is an appropriate time to launch well-designed epidemiological studies so that etiopathogenetic factors can be identified. There is a male predominance in Crohn's disease in the Asian population. The NOD2/CARD15 gene is not associated with CD in the Japanese, Korean, Chinese and Indian population.

Distribution and manifestations of inflammatory bowel disease in Asians, Hispanics, and African Americans: a systematic review

OBJECTIVES

Although inflammatory bowel disease (IBD) has been reported worldwide, most studies have focused on Caucasian populations. Our aim was to summarize the existing epidemiological literature, identify temporal trends, and highlight areas for future research.

METHODS

We carried out a systematic review following standard guidelines to evaluate the incidence, prevalence, temporal trends, disease characteristics, and extra-intestinal manifestations (EIMs) of IBD in African American, Hispanic, and Asian adult patients. Two investigators independently identified eligible studies through 2008 using structured keyword searches in PubMed, applied several inclusion and exclusion criteria, and abstracted the data.

RESULTS

Twenty-eight publications were included, encompassing 1,272 Hispanic, 547 African American, and 35,844 Asian patients with IBD. Greater proportions of Hispanic (36.7-84.3%) and Asian (30.6-74.7%) patients were diagnosed with ulcerative colitis (UC) than with Crohn's disease (CD) compared with African Americans (27.6-40.6%). The prevalence rates of IBD in Hispanics in Puerto Rico varied between 5 (rural) and 62 (urban) per 100,000. Crude prevalence rates in Asia varied between 6 (Singapore) and 136 (South Asians in UK) per 100,000 for UC, and between 3 (Singapore) and 33 (South Asians in UK) per 100,000 for CD. Three studies reported a rising annual incidence rate among Hispanics (from 2.6 to 7.5 per 100,000) and Asians (from 0.22 to 3.62 per 100,000). Fistulizing CD was reported in nearly one-third of Hispanic patients, up to one-quarter of African-American patients, and up to one-half of Asian patients. Ileocolonic disease was the most common site of CD among the three racial/ethnic groups, with skin and joint manifestations noted as the most common EIMs.

CONCLUSIONS

Prevalence and incidence rates in Hispanics and Asians have recently increased. There are many similarities and differences in disease location and behavior among racial/ethnic groups. There is a paucity of literature on all aspects of the disease in Hispanics, in the incidence and prevalence of IBD in African Americans, and in Asians with IBD outside Asia.

Upper gastrointestinal tract phenotype of Crohn's disease is associated with early surgery and further hospitalization

BACKGROUND

According to the Montreal Classification, upper gastrointestinal tract phenotype L4 is uncommon in Caucasian patients with Crohn's disease (CD) but carries excess risk of recurrence. We studied the clinical course of CD in Chinese patients presenting with the L4 phenotype and factors predicting its occurrence upon longitudinal follow-up.

METHODS

This prospective cohort study included 132 Chinese CD patients (median age at diagnosis, 30.0 years, range: 14.0-77.0 years) who were followed for 770 person-years. Demographic data including disease behavior and location, details of surgery, and hospitalization were collected. The Kaplan-Meier method was used to estimate the probabilities of further hospitalization and major surgery followed by Cox proportional hazards regression to determine if clinical variables independently predicted the endpoints.

RESULTS

The L4 phenotype was found in 30 (22.7%) patients at presentation. There were significantly more stricturing (46.7% versus 18.6%) and penetrating (30.0% versus 3.9%) phenotypes in the L4 group than in the non-L4 group (P < 0.0001). The 3-year cumulative probability of further hospitalization was 86.9% (95% confidence interval [CI]: 73.8%-100.0%) in the L4 group as compared with 49.3% (95% CI: 39.3%-59.3%) in the non-L4 group (log-rank test, P < 0.0001). The L4 phenotype independently predicted further hospitalization (adjusted hazards ratio [HR]: 2.1; 95% CI: 1.3-3.5). The cumulative probability of major surgery was significantly higher in the L4 than in the non-L4 group (P < 0.0001). Eighteen (17.6%) patients developed the L4 phenotype on follow-up and the stricturing phenotype predicted its occurrence (adjusted HR: 5.5; 95% CI: 2.2-14.0).

CONCLUSIONS

Chinese CD patients more often had the L4 phenotype, which predicted the need of subsequent hospitalization.

An update on the epidemiology of inflammatory bowel disease in Asia

A rising trend in the incidence and prevalence of inflammatory bowel disease (IBD) in Asia has been recognized for the past two decades. It has been postulated that this phenomenon may be related to the westernization of lifestyles, including changes in dietary habits and environmental changes such as improved sanitation and industrialization. Previously we reported that the incidence and prevalence rates of IBD in Asia were low compared with the West, but there was a notably rising secular trend. In this review, we summarize the recent epidemiological data in Asia, characterize the clinical features, risk factors and genetic susceptibility of Asian IBD patients, and compare these to those of Western IBD patients. In the past decade, the incidence and prevalence of IBD reported across Asia, particularly in East Asia, has continued to increase. Familial clustering is generally uncommon in East Asia but appears to be higher in West Asia. The genetic susceptibilities in Asian IBD patients differ from those of White patients, as NOD2/CARD15 mutations are much less common. The clinical phenotypes and complication rates of Asian IBD resemble the White population in general, but with some differences, including lower surgical rates, higher prevalence of males, and higher prevalence of ileocolonic involvement among East Asian Crohn's disease patients, and a low frequency of primary sclerosing cholangitis among IBD patients in East and Southeast Asia.

Presentation and disease course in early- compared to later-onset pediatric Crohn's disease

BACKGROUND

The relationship between the age at diagnosis and disease course is poorly defined in children with Crohn's disease (CD). We examined the presentation and course of disease in patients 0-5 compared to 6-17 yr of age at diagnosis.

METHODS

We analyzed uniform data from 989 consecutive CD patients collected between January 2000 and November 2003, and stored in the Pediatric IBD Consortium Registry. The statistical tests account for the length of follow-up of each patient.

RESULTS

In total, 98 patients (9.9%) were of 0-5 yr of age at diagnosis. The mean follow-up time was 5.6 +/- 5.0 yr in the younger group and 3.3 +/- 2.8 yr in the older group (P < 0.001). Race/ethnicity differed by the age group (P= 0.015); a larger proportion of the younger group was Asian/Pacific Islander or Hispanic, and a larger proportion of the older group was African American. The initial classification as ulcerative colitis or indeterminate colitis was more common among the 0-5 yr of age group (P < 0.001). The 6-17 yr of age patients presented with more abdominal pain (P < 0.001), weight loss (P= 0.001), or fever (P= 0.07), while the 0-5 yr of age patients presented with more rectal bleeding (P= 0.008). The 6-17 yr of age patients were more likely to be treated with antibiotics (P < 0.001), 6-mercaptopurine/azathioprine (P < 0.001), infliximab (P= 0.001), or corticosteroids (P= 0.0006). The 6-17 yr of age patients had a higher cumulative incidence of treatment with 5-aminosalicylates (P= 0.009) or methotrexate (P= 0.04). The risk for developing an abscess (P= 0.001), a fistula (P= 0.02), a stricture (P= 0.05), or a perianal fissure (P= 0.06) was greater in the 6-17 yr of age patients.

CONCLUSIONS

The 6-17 yr of age patients with CD appear to have a more complicated disease course compared to 0-5 yr of age children. The 0-5 yr of age group may represent a unique disease phenotype and benefit from different approaches to management. Long-term prospective studies are required to validate these findings.

Changes in Crohn's disease phenotype over time in the Chinese population: validation of the Montreal classification system

BACKGROUND

Phenotypic evolution of Crohn's disease occurs in whites but has never been described in other populations. The Montreal classification may describe phenotypes more precisely. The aim of this study was to validate the Montreal classification through a longitudinal sensitivity analysis in detecting phenotypic variation compared to the Vienna classification.

METHODS

This was a retrospective longitudinal study of consecutive Chinese Crohn's disease patients. All cases were classified by the Montreal classification and the Vienna classification for behavior and location. The evolution of these characteristics and the need for surgery were evaluated.

RESULTS

A total of 109 patients were recruited (median follow-up: 4 years, range: 6 months-18 years). Crohn's disease behavior changed 3 years after diagnosis (P = 0.025), with an increase in stricturing and penetrating phenotypes, as determined by the Montreal classification, but was only detected by the Vienna classification after 5 years (P = 0.015). Disease location remained stable on follow-up in both classifications. Thirty-four patients (31%) underwent major surgery during the follow-up period with the stricturing [P = 0.002; hazard ratio (HR): 3.3; 95% CI: 1.5-7.0] and penetrating (P = 0.03; HR: 5.8; 95% CI: 1.2-28.2) phenotypes according to the Montreal classification associated with the need for major surgery. In contrast, colonic disease was protective against a major operation (P = 0.02; HR: 0.3; 95% CI: 0.08-0.8).

CONCLUSIONS

This is the first study demonstrating phenotypic evolution of Crohn's disease in a nonwhite population. The Montreal classification is more sensitive to behavior phenotypic changes than is the Vienna classification after excluding perianal disease from the penetrating disease category and was useful in predicting course and the need for surgery.