A meta-analysis of the role of smoking in inflammatory bowel disease

Changing epidemiological trends of inflammatory bowel disease in Asia

Inflammatory bowel disease (IBD) has become more common in Asia over the past few decades. The rate of increase in prevalence of the disease varies greatly in Asia, with several countries in East Asia experiencing a more than doubled increase in IBD prevalence over the past decade. Historically, ulcerative colitis (UC) is more common than Crohn's disease (CD) in Asia. However, a reverse trend is beginning to appear in more developed countries in Asia such as Japan, Korea, and Hong Kong. While Asian IBD patients share many similarities with their Western counterparts, there are important differences with significant clinical implications. In Asia, there are more men with CD, more ileo-colonic involvement in CD, less familial aggregation, fewer extra-intestinal manifestations and worse clinical outcomes for older-onset patients with UC. These differences are likely related to the different genetic makeup and environmental exposures in different regions. Evaluation of the differences and rates in epidemiologic trends may help researchers and clinicians estimate disease burden and understand the reasons behind these differences, which may hold the key to unravel the etiology of IBD.

The Association of Smoking and Surgery in Inflammatory Bowel Disease is Modified by Age at Diagnosis

Objectives:

We assessed the association of smoking at diagnosis of inflammatory bowel disease (IBD) on the need for an intestinal resection.

Methods:

The Health Improvement Network was used to identify an inception cohort of Crohn's disease (n=1519) and ulcerative colitis (n=3600) patients from 1999–2009. Poisson regression explored temporal trends for the proportion of newly diagnosed IBD patients who never smoked before their diagnosis and the risk of surgery within 3 years of diagnosis. Cox proportional hazard models assessed the association between smoking and surgery, and effect modification was explored for age at diagnosis.

Results:

The rate of never smokers increased by 3% per year for newly diagnosed Crohn's disease patients (incidence rate ratio (IRR) 1.03; 95% confidence interval (CI): 1.02–1.05), but not for ulcerative colitis. The rate of surgery decreased among Crohn's disease patients aged 17–40 years (IRR 0.96; 95% CI: 0.93–0.98), but not for ulcerative colitis. Smoking at diagnosis increased the risk of surgery for Crohn's disease patients diagnosed after the age of 40 (hazard ratio (HR) 2.99; 95% CI: 1.52–5.92), but not for those diagnosed before age 40. Ulcerative colitis patients diagnosed between the ages of 17 and 40 years and who quit smoking before their diagnosis were more likely to undergo a colectomy (ex-smoker vs. never smoker: HR 1.66; 95% CI: 1.04–2.66). The age-specific findings were consistent across sensitivity analyses for Crohn's disease, but not ulcerative colitis.

Conclusions:

In this study, the association of smoking and surgical resection was dependent on the age at diagnosis of IBD.

[Smoking, smoking cessation and Crohn's disease]

CONTEXT

Smoking whose prevalence is higher in patients with Crohn's disease (CD) worsens its evolution. Ulcerative colitis mostly affect non- or ex-smokers; smoking may improve the course of the disease.

OBJECTIVES

Systematic literature review of data on the relationship between smoking, smoking cessation and Crohn'disease.

DOCUMENTARY SOURCES

Medline, on the period 1980-2015 with the keywords "Crohn's disease" or "inflammatory bowel disease" and "smoking" or "smoking cessation"; limits "Title/Abstract"; the selected languages were English or French.

STUDY SELECTION

Among 1315 articles, 168 abstracts have given rise to a dual reading to select 69 studies (case-control, retrospective, reviews or meta-analysis). Data were extracted using a reading gate.

RESULTS

Smoking increases the risk of complications, recurrences and resort of surgery, corticosteroids or immunosuppressants. These deleterious effects are more common in women. Stopping smoking improves the course of the disease and represents an essential component of its management.

LIMITS

Heterogeneity of the studies collected according to the type, population characteristics, definition of smoking status and the validation of smoking cessation.

CONCLUSION

Smokers suffering from CD must routinely be made aware of the disadvantages of smoking, benefits of abstinence and helped to quit smoking.

Smoking is Associated With Extra-intestinal Manifestations in Inflammatory Bowel Disease

BACKGROUND AND AIMS

Smoking affects the course of disease in patients with ulcerative colitis (UC) and Crohn's disease (CD). We aimed to study the association between smoking and extra-intestinal manifestations (EIMs) in inflammatory bowel disease (IBD).

METHODS

We cross-sectionally explored the association between smoking and EIMs in IBD in three cohort studies: (1) the COIN study, designed to estimate healthcare expenditures in IBD; (2) the Groningen study, focused on cigarette smoke exposure and disease behaviour in IBD; and (3) the JOINT study, evaluating joint and back manifestations in IBD.

RESULTS

In the COIN, Groningen and JOINT cohorts, 3030, 797 and 225 patients were enrolled, of whom 16, 24 and 23.5% were current smokers, respectively. Chronic skin disorders and joint manifestations were more prevalent in smoking IBD patients than in non-smokers (COIN, 39.1 vs 29.8%, p <0.01; Groningen, 41.7 vs 30.0%, p <0.01) in both CD and UC. In the JOINT cohort, smoking was more prevalent in IBD patients with joint manifestations than in those without (30.3 vs 13.0%, p <0.01). EIMs appeared to be more prevalent in high- than in low-exposure smokers (56.0 vs 37.1%, p = 0.10). After smoking cessation, the prevalence of EIMs in IBD patients rapidly decreased towards levels found in never smokers (lag time: COIN cohort, 1-2 years; Groningen cohort, within 1 year).

CONCLUSIONS

There is a robust dose-dependent association between active smoking and EIMs in both CD and UC patients. Smoking cessation was found to result in a rapid reduction of EIM prevalence to levels encountered in never smokers.

Smoking Cessation for Crohn's Disease: Clearing the Haze

The TABACROHN Study Group conducted a multicenter prospective cohort study, demonstrating that smoking cessation improved the prognosis of Crohn's disease. Patients who continued to smoke were 50% more likely to relapse compared with non-smokers. Smoking cessation reduced the risk of flaring, regardless of exposure to anti-tumor necrosis factor agents. Despite the evidence that smoking cessation is beneficial, many patients do not quit smoking after their diagnosis of Crohn's disease. Lack of awareness, physical addiction, and social context of smoking inhibit smoking cessation. In spite of this, comprehensive smoking cessation programs have been shown to be effective and reduce costs.

Influence of environmental factors in the development of inflammatory bowel diseases

Idiopathic inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC), are multifactorial diseases that are manifested after disruption of a genetic predisposed individual and its intestinal microflora through an environmental stimulus. Urbanization and industrialization are associated with IBD. Epidemiological data, clinical observations and family/immigrants studies indicate the significance of environmental influence in the development of IBD. Some environmental factors have a different effect on the subtypes of IBD. Smoking and appendectomy is negatively associated with UC, but they are aggravating factors for CD. A westernized high fat diet, full of refined carbohydrates is strongly associated with the development of IBD, contrary to a high in fruit, vegetables and polyunsaturated fatty acid-3 diet that is protective against these diseases. High intake of nonsteroidal antiinflammatory drug and oral contraceptive pills as well as the inadequacy of vitamin D leads to an increased risk for IBD and a more malignant course of disease. Moreover, other factors such as air pollution, psychological factors, sleep disturbances and exercise influence the development and the course of IBD. Epigenetic mechanism like DNA methylation, histone modification and altered expression of miRNAS could explain the connection between genes and environmental factors in triggering the development of IBD.

The global burden of IBD: from 2015 to 2025

Over 1 million residents in the USA and 2.5 million in Europe are estimated to have IBD, with substantial costs for health care. These estimates do not factor in the 'real' price of IBD, which can impede career aspirations, instil social stigma and impair quality of life in patients. The majority of patients are diagnosed early in life and the incidence continues to rise; therefore, the effect of IBD on health-care systems will rise exponentially. Moreover, IBD has emerged in newly industrialized countries in Asia, South America and Middle East and has evolved into a global disease with rising prevalence in every continent. Understanding the worldwide epidemiological patterns of IBD will prepare us to manage the burden of IBD over time. The goal of this article is to establish the current epidemiology of IBD in the Western world, contrast it with the increase in IBD in newly industrialized countries and forecast the global effects of IBD in 2025.

Crohn's disease: a clinical update

Crohn's disease is increasing in prevalence worldwide. It arises from a complex interplay between both genetic predisposition and environmental influence. A search of databases and clinical practice guidelines was performed to provide the most up-to-date evidence-based approach for diagnosing and managing patients with Crohn's disease. No single gold standard investigation exists. Whilst full ileocolonoscopy with biopsies remains the mainstay for diagnosis, other less invasive imaging modalities are being actively considered in the workup, as well as the use of serological markers. Management should incorporate dietary and lifestyle modifications where necessary, the use of medications in induction and remission of disease, and consideration of surgical intervention where medical therapy has failed.

The Demographic and Clinical Characteristics of Ulcerative Colitis in a Northeast Brazilian Population

INTRODUCTION

The purpose of this study was to describe the clinical and demographic characteristics of UC in Bahia, a Brazilian state, and to identify the variables associated with extensive colitis, steroid therapy, immunosuppression, and colectomy.

METHODS

In this cross-sectional study UC patients were interviewed, and additional information was collected from the medical records. Descriptive statistics and multivariate Poisson regression analysis were used.

RESULTS

This study included 267 individuals, the mean age of whom was 39.4 years at diagnosis. There was a predominance of females and left-side colitis. Extensive colitis was positively associated with male gender, diarrhea, weight loss, and a younger age at diagnosis. In contrast, active smoking and a family history of IBD were negatively associated with extensive colitis. Positive associations were observed between steroid therapy and diarrhea, weight loss, urban patients, extraintestinal manifestations (EIMs), and hospitalization. Younger age and weight loss at diagnosis, a family history of IBD, extensive colitis, EIMs, hospitalization, and steroid therapy were all positively associated with immunosuppression. In contrast, Caucasian individuals, smokers, patients with rectal bleeding, and rural patients areas were all observed to have a decreased likelihood of immunosuppression.

CONCLUSIONS

Our results corroborate the association between higher prevalence of extensive colitis and younger age at diagnosis. An association between steroid therapy and clinical presentation at diagnosis was observed. The observation that white individuals and rural patients use less immunosuppressive drugs highlights the need to study the influence of environmental and genetic factors on the behavior of UC in this population.

Smoking-induced expression of the GPR15 gene indicates its potential role in chronic inflammatory pathologies

Despite the described clear epigenetic effects of smoking, the effect of smoking on genome-wide gene expression in the blood is obscure. We therefore studied the smoking-induced changes in the gene-expression profile of the peripheral blood. RNA was extracted from the whole blood of 48 individuals with a detailed smoking history (24 never-smokers, 16 smokers, and 8 ex-smokers). Gene-expression profiles were evaluated with RNA sequencing, and results were analyzed separately in 24 men and 24 women. In the male smokers, 13 genes were statistically significantly (false-discovery rate <0.1) differentially expressed; in female smokers, 5 genes. Although most of the differentially expressed genes were different between the male and female smokers, the G-protein-coupled receptor 15 gene (GPR15) was differentially expressed in both male and female smokers compared with never-smokers. Analysis of GPR15 methylation identified significantly greater hypomethylation in smokers compared with that in never-smokers. GPR15 is the chemoattractant receptor that regulates T-cell migration and immunity. Up-regulation of GPR15 could explain to some extent the health hazards of smoking with regard to chronic inflammatory diseases.

Beliefs and behaviour about smoking among inflammatory bowel disease patients

BACKGROUND AND AIMS

We investigated the beliefs and behaviours about tobacco among inflammatory bowel disease (IBD) patients.

MATERIALS AND METHODS

A questionnaire of 18 items was developed and administered to all consecutive patients followed for IBD at Nancy University Hospital from October 2012 to March 2013.

RESULTS

Two hundred and thirty-one patients participated in the survey [Crohn's disease (CD)=171, ulcerative colitis (UC)=60]. Among IBD patients who were smokers at diagnosis, 10.5% of CD patients versus 14.3% of UC patients believed that tobacco could have triggered their IBD; about half the CD smokers at diagnosis were not aware that smoking might promote their disease. Three quarters of smokers after diagnosis knew that tobacco was not beneficial for their CD, whereas all UC were aware that smoking had a beneficial effect on their disease course. About half of the CD patients had stopped smoking during a flare-up. Four former smokers with UC (21.1%) resumed smoking during a relapse. Nearly 90% of IBD current smokers wished to quit smoking. About half the IBD patients were aware of the relation between smoking and IBD, and the Internet was a source for 24.3% of these patients.

CONCLUSION

The majority of IBD patients are unaware of the effects of tobacco on their disease. Better information through a therapeutic education programme should be systematically recommended in IBD.

Smoking prevalence and its influence on disease course and surgery in Crohn's disease and ulcerative colitis

BACKGROUND

Smoking demonstrates divergent effects in Crohn's disease (CD) and ulcerative colitis (UC). Smoking frequency is greater in CD and deleterious to its disease course. Conversely, UC is primarily a disease of nonsmokers and ex-smokers, with reports of disease amelioration in active smoking.

AIM

To determine the prevalence of smoking and its effects on disease progression and surgery in a well-characterised cohort of inflammatory bowel diseases (IBD) patients.

METHODS

Patients with smoking data of the Sydney IBD Cohort were included. Demographic, phenotypic, medical, surgical and hospitalisation data were analysed and reported on the basis of patient smoking status.

RESULTS

1203 IBD patients were identified comprising 626 CD and 557 UC with 6725 and 6672 patient-years of follow-up, respectively. CD patients were more likely to smoke than UC patients (19.2% vs. 10.2%, P < 0.001). A history of smoking in CD was associated with an increased proportional surgery rate (45.8% vs. 37.8%, P = 0.045), requirement for IBD-related hospitalisation (P = 0.009) and incidence of peripheral arthritis (29.8% vs. 22.0%, P = 0.027). Current smokers with UC demonstrated reduced corticosteroid utilisation (24.1% vs. 37.5%, P = 0.045), yet no reduction in the rates of colectomy (3.4% vs. 6.6%, P = 0.34) or hospital admission (P = 0.25) relative to nonsmokers. Ex-smokers with UC required proportionately greater immunosuppressive (36.2% vs. 26.3%, P = 0.041) and corticosteroid (43.7% vs. 34.5%, P = 0.078) therapies compared with current and never smokers.

CONCLUSIONS

This study confirms the detrimental effects of smoking in CD, yet failed to demonstrate substantial benefit from smoking in UC. These data should encourage all patients with IBD to quit smoking.

Extraintestinal manifestations of inflammatory bowel disease and the influence of smoking

AIMS

To define the number/frequency of organ systems affected by extraintestinal manifestations (EIMs), to identify factors affecting the clinical course of inflammatory bowel disease (IBD) and EIM development, and to determine the impact of smoking, disease duration and location on the diagnosis of EIMs in Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

IBD patients were derived from a single university colorectal surgery practice. Smoking data were obtained through a modified Behavioral Risk Factor Surveillance System survey. The frequencies of arthritis/arthralgia, primary sclerosing cholangitis (PSC), ocular and cutaneous EIMs were determined.

RESULTS

Of the 757 patients evaluated (CD 488, UC 269), 50% had ≥1 EIM. Arthritis/arthralgia, cutaneous and ocular EIMs were significantly higher in frequency in CD compared to UC patients. Prolonged disease duration was associated with increased prevalence of arthritis/arthralgia in IBD (p ≤ 0.001) as well as PSC (p = 0.049), ocular (p = 0.030) and cutaneous (p = 0.009) EIMs in CD. Disease location affected the occurrence of EIMs in CD. Smoking appeared to increase the prevalence of ocular EIMs in UC (p = 0.026).

CONCLUSION

Arthritis/arthralgia, cutaneous and ocular EIMs occurred in a significantly higher proportion of CD patients. CD patients with longer disease duration had a significantly higher prevalence of PSC, ocular and cutaneous EIMs. Smoking was found to increase ocular EIMs in UC.

Funding a smoking cessation program for Crohn's disease: an economic evaluation

OBJECTIVES

Patients with Crohn's disease (CD) who smoke are at a higher risk of flaring and requiring surgery. Cost-effectiveness studies of funding smoking cessation programs are lacking. Thus, we performed a cost-utility analysis of funding smoking cessation programs for CD.

METHODS

A cost-utility analysis was performed comparing five smoking cessation strategies: No Program, Counseling, Nicotine Replacement Therapy (NRT), NRT+Counseling, and Varenicline. The time horizon for the Markov model was 5 years. The health states included medical remission (azathioprine or antitumor necrosis factor (anti-TNF), dose escalation of an anti-TNF, second anti-TNF, surgery, and death. Probabilities were taken from peer-reviewed literature, and costs (CAN$) for surgery, medications, and smoking cessation programs were estimated locally. The primary outcome was the cost per quality-adjusted life year (QALY) gained associated with each smoking cessation strategy. Threshold, three-way sensitivity, probabilistic sensitivity analysis (PSA), and budget impact analysis (BIA) were carried out.

RESULTS

All strategies dominated No Program. Strategies from most to least cost effective were as follows: Varenicline (cost: $55,614, QALY: 3.70), NRT+Counseling (cost: $58,878, QALY: 3.69), NRT (cost: $59,540, QALY: 3.69), Counseling (cost: $61,029, QALY: 3.68), and No Program (cost: $63,601, QALY: 3.67). Three-way sensitivity analysis demonstrated that No Program was only more cost effective when every strategy's cost exceeded approximately 10 times their estimated costs. The PSA showed that No Program was the most cost-effective <1% of the time. The BIA showed that any strategy saved the health-care system money over No Program.

CONCLUSIONS

Health-care systems should consider funding smoking cessation programs for CD, as they improve health outcomes and reduce costs.

Smoking and early infliximab response in Crohn’s disease: a meta-analysis

BACKGROUND

Infliximab is used to treat moderate to severe Crohn’s disease (CD), but its efficacy varies. Although cigarette smoking worsens CD, its impact on the infliximab response is unknown. We conducted a systematic review and meta-analysis of clinical trials to determine the effect of smoking on the induction response to infliximab.

METHODS

A systematic search was performed of MEDLINE, EMBASE, CINAHL, the Cochrane central register of controlled trials, the Cochrane IBD Group Specialized Trials Register for publications, and abstracts from major conferences from January 1996 to December 2010. Random effects meta-analysis using the Mantel–Haenszel method was conducted. Heterogeneity across studies was assessed using the Q statistic, the I2 statistic, and τ2.

RESULTS

We identified 12 articles; four were excluded due to use of non-validated scoring systems.The remaining eight included a total of 1658 patients, with 649 active smokers. Luminal response was assessed by the Crohn’s Disease Activity Index in four studies (three of which included fistula response) and the Harvey–Bradshaw index in two (both including fistula response), and two studies examined only the fistula response. The relative risk for response to infliximab among smokers was 0.99 (95% CI 0.88–1.11) (τ2 = 0.0143). Analyses of the five studies examining both inflammatory and fistulizing CD were similar to the analysis of all eight studies. The pooled relative risk was 0.92 (95% CI 0.80–1.06) (τ2 = 0.0154).

CONCLUSION

Though smoking worsens CD, this meta-analysis does not show a negative effect of smoking on initial response to infliximab. This must be viewed in the proper context, as long-term maintenance of response may yet be influenced by smoking status.

Environment and the inflammatory bowel diseases

Inflammatory bowel diseases (IBD), which consists of Crohn disease and ulcerative colitis, are chronic inflammatory conditions of the gastrointestinal tract. In genetically susceptible individuals, the interaction between environmental factors and normal intestinal commensal flora is believed to lead to an inappropriate immune response that results in chronic inflammation. The incidence of IBD have increased in the past century in developed and developing countries. The purpose of the present review is to summarize the current knowledge of the association between environmental risk factors and IBD. A number of environmental risk factors were investigated including smoking, hygiene, microorganisms, oral contraceptives, antibiotics, diet, breastfeeding, geographical factors, pollution and stress. Inconsistent findings among the studies highlight the complex pathogenesis of IBD. Additional studies are necessary to identify and elucidate the role of environmental factors in IBD etiology.

Adalimumab for maintenance therapy for one year in Crohn's disease: results of a Latin American single-center observational study

CONTEXT

Adalimumab is a fully-human antibody that inhibits TNF alpha, with a significant efficacy for long-term maintenance of remission. Studies with this agent in Latin American Crohn's disease patients are scarce.

OBJECTIVES

The objective of this study was to outline clinical remission rates after 12 months of adalimumab therapy for Crohn's disease patients.

METHODS

Retrospective, single-center, observational study of a Brazilian case series of Crohn's disease patients under adalimumab therapy. Variables analyzed: demographic data, Montreal classification, concomitant medication, remission rates after 1, 4, 6 and 12 months. Remission was defined as Harvey-Bradshaw Index ≤ 4, and non-responder-imputation and last-observation-carried-forward analysis were used. The influence of infliximab on remission rates was analyzed by Fischer and Chi-square tests (P<0.05).

RESULTS

Fifty patients, with median age of 35 years at therapy initiation, were included. Remission rates after 12 months of therapy were 54% under non-responder-imputation and 88% under last-observation-carried-forward analysis. After 12 months, remission on patients with previous infliximab occurred in 69.23% as compared to 94.59% in infliximab-naïve patients (P = 0.033).

CONCLUSIONS

Adalimumab was effective in maintaining clinical remission after 12 months of therapy, with an adequate safety profile, and was also more effective in infliximab naïve patients.

Carbohydrate intake in the etiology of Crohn's disease and ulcerative colitis

BACKGROUND

Diet may have a role in the etiology of inflammatory bowel disease. In previous studies, the associations between increased intakes of carbohydrates, sugar, starch, and inflammatory bowel disease are inconsistent. However, few prospective studies have investigated the associations between these macronutrients and incident Crohn's disease (CD) or ulcerative colitis (UC).

METHODS

A total of 401,326 men and women were recruited between 1991 and 1998. At recruitment, dietary intakes of carbohydrate, sugar, and starch were measured using validated food frequency questionnaires. The cohort was monitored identifying participants who developed incident CD or UC. Cases were matched with 4 controls, and odds ratios were calculated for quintiles of total carbohydrate, sugar, and starch intakes adjusted for total energy intake, body mass index, and smoking.

RESULTS

One hundred ten participants developed CD, and 244 participants developed UC during follow-up. The adjusted odds ratio for the highest versus the lowest quintiles of total carbohydrate intake for CD was 0.87, 95% CI = 0.24 to 3.12 and for UC 1.46, 95% CI = 0.62 to 3.46, with no significant trends across quintiles for either (CD, P trend = 0.70; UC, P trend = 0.41). Similarly, no associations were observed with intakes of total sugar (CD, P trend = 0.50; UC, P trend = 0.71) or starch (CD, P trend = 0.69; UC, P trend = 0.17).

CONCLUSIONS

The lack of associations with these nutrients is in agreement with many case-control studies that have not identified associations with CD or UC. As there is biological plausibility for how specific carbohydrates could have an etiological role in inflammatory bowel disease, future epidemiological work should assess individual carbohydrates, although there does not seem to be a macronutrient effect.

Immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of idiopathic, chronic and relapsing inflammatory conditions of the gastrointestinal tract. Familial and epidemiological studies have stressed the involvement of genetic factors and have also shown the critical role of environmental factors such as sanitation and hygiene in the development of IBD. However, the molecular mechanisms of intestinal inflammation in IBD have long remained unknown. In recent years, the study of susceptibility genes involved in the detection of bacterial components and in the regulation of the host immune response has shed light onto the potential role of intestinal pathogens and gut flora in IBD immunobiology. This review presents current knowledge on intestinal epithelial barrier alterations and on dysfunction of mucosal innate and acquired immune responses in IBD. The data support the etiological hypothesis which argues that pathogenic intestinal bacteria and/or infectious agents initiate and perpetuate the inflammation of the gut through disruption of tolerance towards the commensal microbiota in an individual with genetic vulnerability.

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.

Smoking in inflammatory bowel disease: impact on disease course and insights into the aetiology of its effect

The chronic intestinal inflammation that characterises Crohn's disease and ulcerative colitis arises from a complex interplay between host genotype, the immune system, and the intestinal microbiota. In addition, environmental factors such as smoking impact on disease onset and progression. Individuals who smoke are more likely to develop Crohn's disease, and smoking is associated with recurrence after surgery and a poor response to medical therapy. Conversely, smoking appears protective against ulcerative colitis and smokers are less likely to require colectomy. The mechanism by which smoking exerts its impact on disease and the rational for the dichotomous effect in patients with Crohn's disease and ulcerative colitis is not clear. Recent evidence suggests that smoking induces alterations to both the innate and acquired immune system. In addition, smoking is associated with a distinct alteration in the intestinal microbiota both in patients with active Crohn's disease and healthy subjects.

Current concepts in the molecular pathogenesis of thyroid-associated ophthalmopathy

Graves' disease (GD) is a common autoimmune condition. At its core, stimulatory autoantibodies are directed at the thyroid-stimulating hormone receptor (TSHR), resulting in dysregulated thyroid gland activity and growth. Closely associated with GD is the ocular condition known as thyroid-associated ophthalmopathy (TAO). The pathogenesis of TAO remains enigmatic as do the connections between the thyroid and orbit. This review highlights the putative molecular mechanisms involved in TAO and suggests how these insights provide future directions for identifying therapeutic targets. Genetic, epigenetic, and environmental factors have been suggested as contributory to the development of GD and TAO. Thyroid-stimulating hormone receptor and insulin-like growth factor receptor (IGF-1R) are expressed at higher levels in the orbital connective tissue from individuals with TAO than in healthy tissues. Together, they form a functional complex and appear to promote signaling relevant to GD and TAO. Orbital fibroblasts display an array of cell surface receptors and generate a host of inflammatory molecules that may participate in T and B cell infiltration. Recently, a population of orbital fibroblasts has been putatively traced to bone marrow-derived progenitor cells, known as fibrocytes, as they express CD45, CD34, CXCR4, collagen I, functional TSHR, and thyroglobulin (Tg). Fibrocytes become more numerous in GD and we believe traffic to the orbit in TAO. Numerous attempts at developing complete animal models of GD have been largely unsuccessful, because they lack fidelity with the ocular manifestations seen in TAO. Better understanding of the pathogenesis of TAO and development of improved animal models should greatly accelerate the identification of medical therapy for this vexing medical problem.

Air pollution effects on the gut microbiota: a link between exposure and inflammatory disease

Global incidence rates for inflammatory bowel disease (IBD) have gradually risen over the past 20 years. Genome-wide association studies (GWAS) have identified over 160 genetic loci associated with IBD; however, inherited factors only account for a partial contribution to the disease risk. We have recently shown that urban airborne particulate matter (PM) ingested via contaminated food can alter gut microbiome and immune function under normal and inflammatory conditions. In this addendum, we will discuss how PM can modify the gut microbial form and function, provide evidence on changes seen in intestinal barrier, and suggest a working hypothesis of how pollutants affect the gastrointestinal tract. The significance of the work presented could lead to identifying airborne pollutants as potential risk factors and thus provide better patient care management.

Natural history of elderly-onset inflammatory bowel disease: a population-based cohort study

Data on the natural history of elderly-onset inflammatory bowel disease (IBD) are scarce.

METHODS

In a French population-based cohort we identified 841 IBD patients >60 years of age at diagnosis from 1988 to 2006, including 367 Crohn's disease (CD) and 472 ulcerative colitis (UC).

RESULTS

Median age at diagnosis was similar for CD (70 years (IQR: 65-76)) and UC (69 years (64-74)). Median follow-up was 6 years (2-11) for both diseases. At diagnosis, in CD, pure colonic disease (65%) and inflammatory behaviour (78%) were the most frequent phenotype. At maximal follow-up digestive extension and complicated behaviour occurred in 8% and 9%, respectively. In UC, 29% of patients had proctitis, 45% left-sided and 26% extensive colitis without extension during follow-up in 84%. In CD cumulative probabilities of receiving corticosteroids (CSs), immunosuppressants (ISs) and anti tumor necrosis factor therapy were respectively 47%, 27% and 9% at 10 years. In UC cumulative probabilities of receiving CS and IS were 40% and 15%, respectively at 10 years. Cumulative probabilities of surgery at 1 year and 10 years were 18% and 32%, respectively in CD and 4% and 8%, respectively in UC. In CD complicated behaviour at diagnosis (HR: 2.6; 95% CI 1.5 to 4.6) was associated with an increased risk for surgery while CS was associated with a decreased risk (HR: 0.5; 0.3 to 0.8). In UC CS was associated with an increased risk (HR: 2.2; 1.1 to 4.6) for colectomy.

CONCLUSIONS

Clinical course is mild in elderly-onset IBD patients. This information would need to be taken into account by physicians when therapeutic strategies are established.

Epidemiological studies of migration and environmental risk factors in the inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are idiopathic chronic diseases of the gastrointestinal tract well known to be associated with both genetic and environmental risk factors. Permissive genotypes may manifest into clinical phenotypes under certain environmental influences and these may be best studied from migratory studies. Exploring differences between first and second generation migrants may further highlight the contribution of environmental factors towards the development of IBD. There are few opportunities that have been offered so far. We aim to review the available migration studies on IBD, evaluate the known environmental factors associated with IBD, and explore modern migration patterns to identify new opportunities and candidate migrant groups in IBD migration research.

Role of genes, the environment and their interactions in the etiology of inflammatory bowel diseases

Few of the studied genes demonstrate association with inflammatory bowel disease (IBD). Three mutations in the nucleotide-binding oligomerization domain 2 gene have consistently shown to be independent risk factors for Crohn's disease, but none of the alleles exhibited high sensitivity or specificity for IBD. Linkage analysis implicated several loci on various chromosomes, and epistasis has been demonstrated. The etiopathogenesis of IBD remains unknown, and environmental contribution to their pathogenesis is evident from genetic studies that demonstrated incomplete monozygotic twins concordandance rate for both Crohn's and ulcerative colitis. Smoking has shown an opposite effect on disease phenotype, with an adverse effect on disease course for Crohn's disease, but a slight beneficial effect in ulcerative colitis. The contribution of infectious agents to susceptibility to IBD appears to be strong. However, the role of nutrition on the etiology and therapy of IBD is not clear. Inconsistencies in environmental risk factors could be due to gene-environment interactions, making it essential to study the role of genetics and environmental contribution to the etiopathology of IBD. Transgenic or knockout mice, such as interleukin-10(-/-), T-cell receptor alpha(-/-), Galphai(2) (-/-) and N-cadherin(-/-), develop colitis-like inflammation similar to humans. Therefore, animal models must be further studied to explore mechanistic interactions.

Dietary arachidonic and oleic acid intake in ulcerative colitis etiology: a prospective cohort study using 7-day food diaries

INTRODUCTION

Dietary fatty acids may be involved in the etiology of ulcerative colitis (UC). Arachidonic acid (AA), an n-6 polyunsaturated fatty acid, is a precursor of the proinflammatory cytokines prostaglandin E2 and leukotriene B4, and its metabolism is competitively inhibited by oleic acid (OA). This study aimed to prospectively investigate whether AA is positively and OA is negatively associated with incident UC development, using data from 7-day food diaries.

METHODS

A total of 25 639 men and women, aged between 40 and 79 years, from Norfolk, UK, were recruited into the prospective European Prospective Investigation into Cancer (EPIC)-Norfolk cohort between 1993 and 1997. At baseline, participants completed 7-day food diaries, checked by nutritionists using a database containing 11 000 foods and 55 000 portion sizes. The cohort was monitored until June 2004 to identify participants who developed UC. Each patient was matched for age and sex with four controls, and conditional logistic regression was used to calculate adjusted odds ratios for AA and OA intakes, and UC association.

RESULTS

Of the participants, 26 (58% men) developed incident UC (53% left sided) after a median follow-up time of 3.8 years (0.5-8.3 years). The highest AA tertile was positively associated with an odds ratio of 6.09 [95% confidence interval (CI) 1.05-35.23], with a trend across tertiles [odds ratio (OR) 2.43, 95% CI 1.06-5.61, P=0.04]. The highest tertile of OA intake was inversely associated with a 0.03 OR for UC (95% CI 0.002-0.56) and an inverse trend (OR 0.30, 95% CI 0.10-0.90, P=0.03).

CONCLUSION

Dietary AA was positively and OA was inversely associated with UC development, with large effect sizes in a dose-dependent manner. This supports roles for measuring these nutrients in future etiological studies and modifying intake in future interventional studies in patients with established disease.

Crohn's disease and smoking: is it ever too late to quit?

BACKGROUND

Smoking increases CD risk. The aim was to determine if smoking cessation at, prior to, or following, CD diagnosis affects medication use, disease phenotypic progression and/or surgery.

METHODS

Data on CD patients with disease for ≥5 yrs were collected retrospectively including the Montreal classification, smoking history, CD-related abdominal surgeries, family history, medication use and disease behaviour at diagnosis and the time when the disease behaviour changed.

RESULTS

1115 patients were included across six sites (mean follow-up-16.6 yrs). More non-smokers were male (p=0.047) with A1 (p<0.0001), L4 (p=0.028) and perianal (p=0.03) disease. Non-smokers more frequently received anti-TNF agents (p=0.049). (p=0.017: OR 2.5 95%CI 1.18-5.16) and those who ceased smoking prior to diagnosis (p=0.045: OR 2.3 95%CI 1.02-5.21) progressed to complicated (B2/B3) disease as compared to those quitting at diagnosis. Patients with uncomplicated terminal ileal disease at diagnosis more frequently developed B2/B3 disease than isolated colonic CD (p<0.0001). B2/B3 disease was more frequent with perianal disease (p<0.0001) and if i.v. steroids (p=0.004) or immunosuppressants (p<0.0001) were used. 49.3% (558/1115) of patients required at least one intestinal surgery. More smokers had a 2nd surgical resection than patients who quit at, or before, the 1st resection and non-smokers (p=0.044: HR=1.39 95%CI 1.01-1.91). Patients smoking >3 cigarettes/day had an increased risk of developing B2/B3 disease (p=0.012: OR 3.8 95%CI 1.27-11.17).

CONCLUSION

Progression to B2/B3 disease and surgery is reduced by smoking cessation. All CD patients regardless of when they were diagnosed, or how many surgeries, should be strongly encouraged to cease smoking.

Locally injected Infliximab ameliorates murine DSS colitis: differences in serum and intestinal levels of drug between healthy and colitic mice

BACKGROUND

Infliximab is effective in human and murine IBD, but its pharmacodynamic is still poorly known. The aim of this study was to assess the affinity of infliximab to murine TNF-α, its role in murine colitis when administered intra-rectally and its levels in the blood, gut mucosa and stool of healthy and sick mice.

METHODS

An ELISA kit was built in order to assess the affinity of infliximab to human or murine-TNF-α. Human IgG were used as controls. DSS model of colitis on C57BL/6 mice was used to assess clinical efficacy of infliximab administered intravenously or by enema. Stool, serum and colon samples were collected to assess infliximab levels and histology for Rachmilewitz score.

RESULTS

Infliximab showed a good affinity both for human-TNF-α and murine-TNF-α. In DSS colitic mice infliximab ameliorated the severity of colitis, regardless of the administration route. In comparison with colitic mice, healthy mice displayed higher serum and mucosal infliximab levels, while detectable levels of infliximab were found in faeces, particularly in colitic mice.

CONCLUSION

Our data support murine models to study infliximab pharmacokinetics and dynamics. Measurable levels of infliximab can be found at different concentrations in blood, intestinal mucosa and stool from healthy and sick mice, thus infliximab pharmacokinetics could have a major impact in human IBD.

New therapeutic avenues in ulcerative colitis: thinking out of the box

Ulcerative colitis (UC) is a chronic idiopathic inflammatory disease of the gastrointestinal tract that affects the mucosal lining of the colon. Recent epidemiological data show that its incidence and prevalence are increasing in many parts of the world, in parallel with altered lifestyles, improved access to health, improved sanitation and industrialisation rates. Current therapeutic strategies for treating UC have only been moderately successful. Despite major recent advances in inflammatory bowel disease therapeutic resources, a considerable proportion of patients are still refractory to conventional treatment. Less than half of all patients achieve long-term remission, many require colectomy, and the disease still has a major impact on patients' lives. Moreover, recent data point to slightly raised mortality. While these outcomes could be partly improved by optimising current therapeutic strategies, they clearly highlight the need to develop new therapies. Currently, a number of promising and innovative therapeutic approaches are being explored, some of which will hopefully survive to reach the clinic. Until such a time arrives, it is important that a better understanding of the clinical particularities of the disease, an improved knowledge of the host-microbiome negative interactions and of the environmental factors beyond disease development is achieved to obtain the final and desired outcome: to provide better treatment and quality of life for patients with this disabling disease.

A clinical review of recent findings in the epidemiology of inflammatory bowel disease

Inflammatory bowel diseases (IBD), including both Crohn's disease and ulcerative colitis, are disorders of chronic inflammation of the gastrointestinal tract marked by episodes of relapse and remission. Over the past several decades, advances have been made in understanding the epidemiology of IBD. The incidence and prevalence of both Crohn's disease and ulcerative colitis have been increasing worldwide across pediatric and adult populations. As IBD is thought to be related to a combination of individual genetic susceptibility, environmental triggers, and alterations in the gut microbiome that stimulate an inflammatory response, understanding the potentially modifiable environmental risk factors associated with the development or the course of IBD could impact disease rates or management in the future. Current hypotheses as to the development of IBD are reviewed, as are a host of environmental cofactors that have been investigated as both protective and inciting factors for IBD onset. Such environmental factors include breast feeding, gastrointestinal infections, urban versus rural lifestyle, medication exposures, stress, smoking, and diet. The role of these factors in disease course is also reviewed. Looking forward, there is still much to be learned about the etiology of IBD and how specific environmental exposures intimately impact the development of disease and also the potential for relapse.

Ulcerative colitis: prevention of relapse

The clinical management of ulcerative colitis (UC) involves first treating the acute symptoms to induce remission, and then successfully maintaining it. Oral 5-aminosalicylic acids are safe and useful for maintaining remission in patients with UC. In terms of adherence, a once-daily form of 5-aminosalicylic acid is superior in maintaining remission as compared with split dosing. Patients at high risk of relapse may be candidates for treatment with thiopurines and/or biologics in the early stages of UC. Calcineurin inhibitors, such as cyclosporine and tacrolimus, are effective for severe, steroid-refractory UC patients. It is suggested that these patients use thiopurines as their maintenance therapy once they achieve remission with calcineurin inhibitors. Recent studies have confirmed that biologics are effective for inducing clinical and endoscopic remission of UC, and thus they may improve long-term prognosis of UC.

High smoking cessation rate in Crohn's disease patients after physician advice--the TABACROHN Study

INTRODUCTION

Tobacco smoking has a significant impact on the development of Crohn's disease (CD) and its clinical course, making smoking cessation one of the main goals in CD therapeutic strategy.

AIMS

To evaluate the effectiveness of an advice-based smoking cessation strategy among CD patients.

METHODS

We have performed a prospective multicenter study which enrolled 408 CD smokers. At inclusion all patients were instructed about the risks of smoking and subsequently followed every 3 months. Each center used additional smoking cessation strategies based on available resources. Urinary cotinine and exhaled carbon monoxide levels were evaluated in a subgroup of patients.

RESULTS

Median study follow up was 18 months. 31% of the patients achieved complete smoking cessation and 23% were smoking-free at the end of their follow up with 8% of smoking relapse. Most patients not achieving smoking cessation did not change their smoking habit with only 5% presenting a decrease in tobacco load. 63% of patients willing to quit smoking received help from another specialist, most frequently the pulmonologist (47%). Surprisingly, most patients (88%) tried to quit smoking with no pharmacological therapy and bupropion, varenicline and nicotine replacement treatment were used in few patients. Urinary cotinine and exhaled CO levels tested in a subgroup of patients proved to have a good correlation with the self-reported smoking habit. No predictors of successful smoking cessation were identified.

CONCLUSION

Our results underline that an anti-tobacco strategy mostly based on CD patients's education and counseling is feasible and effective in helping patients reach complete abstinence.

Crohn's disease in Caucasians and African Americans, as defined by clinical predictors and single nucleotide polymorphisms

OBJECTIVES

To compare three aspects of Crohn's disease (CD) between African Americans and Caucasians: (1) demographic data and environmental factors affecting CD susceptibility, (2) disease presentation and clinical course, and (3) genetic susceptibility via the use of single nucleotide polymorphism (SNP) data for inflammatory bowel disease (IBD) susceptibility loci.

METHODS

Clinical data and peripheral blood were obtained from 1032 patients (554 CD patients and 478 controls) derived from a clinically well-defined university-based medical and surgical digestive disease practice and included those who were diagnosed with IBD. Genomic DNA was extracted and polymerase chain reaction (PCR) amplification and genotyping were performed for 11 SNPs, including the NOD2, IL-23r, OCTN 1, and the IGR gene variants.

RESULTS

A total of 554 patients with CD were included in this study: 53 African Americans (10%), 485 Caucasians (87%), and 15 of other races (3%). The strongest demographic predictor of CD in African American patients was a family history of IBD. Ileocolic disease (L3) was the most common site involved in both African Americans and Caucasians, while the penetrating phenotype (B3) was the most common CD disease behavior in both races. Genotype association analysis showed a significant association between 2 IL23r gene SNPs and CD susceptibility in African Americans (p = .016 and .028, respectively).

CONCLUSION

We believe this study is the first to report on genotype-phenotype associations in African American CD patients and compare findings to Caucasian CD patients within the same geographic area. We found no association between NOD2 gene SNPs and CD susceptibility in African Americans patients (p > .05).

Environmental factors and risk of developing paediatric inflammatory bowel disease -- a population based study 2007-2009

BACKGROUND AND AIMS

To identify environmental risk factors for developing inflammatory bowel disease (IBD) in children <15 years of age.

METHODS

IBD patients and randomly selected healthy controls from a well defined geographical area in Denmark were prospectively recruited in the period 1.1.2007-31.12.2009. Data regarding socioeconomic status, area of residence, living conditions, infections and diet were obtained by a questionnaire.

RESULTS

A total of 118 IBD patients (59 Crohn's disease (CD), 56 ulcerative colitis (UC) and 3 IBD unclassified (IBDU)) and 477 healthy controls filled out the questionnaire. The response rates were 91% in patients and 45% in controls, respectively. Several risk factors for IBD were identified: IBD in first degree relatives (IBD: OR (odds ratio): 6.1 (95%CI: 2.5-15.0), CD (OR: 6.8 (2.3-20.2)) and UC (OR: 6.1 (2.3-16.0))); bedroom sharing (IBD: OR: 2.1 (1.0-4.3), CD (OR: 3.6 (1.3-9.4))); high sugar intake (IBD: OR: 2.5 (1.0-6.2), CD (OR: 2.9 (1.0-8.5))); prior admission to a hospital for gastrointestinal infections (IBD: 7.7 (3.1-19.1), CD (7.9 (2.5-24.9)) and UC (7.4 (2.5-21.6))); stressful events (IBD: 1.7 (1.0-2.9)). Protective factors were daily vs. less than daily vegetable consumption (CD: 0.3 (0.1-1.0), UC (0.3 (0.1-0.8))) and whole meal bread consumption (IBD: OR: 0.5 (0.3-0.9), CD (0.4 (0.2-0.9))). An increased risk of diagnosis of CD compared to UC was shown for patients living in more urban areas (OR: 1.3 (1.1-1.6)).

CONCLUSION

We identified several risk and protective factors for developing IBD. Studies on the influence of environmental factors are important in our understanding of aetiology and phenotypes of paediatric IBD.

Does smoking influence Crohn's disease in the biologic era? The TABACROHN study

BACKGROUND

While most studies have found a negative effect of smoking on Crohn's disease (CD) phenotype, more recent data have failed to reproduce this association, which might be due to a current wider use of thiopurines and biologic therapy. The TABACROHN study aimed at defining the impact of smoking on CD in the largest published series.

METHODS

This multicenter cross-sectional study included 1170 CD patients. Patients were classified as nonsmokers, current smokers, or former smokers according to their present smoking status. Clinical data regarding disease characteristics, treatment, and complications were collected.

RESULTS

Smokers were more frequently under maintenance treatment when compared to nonsmokers. In addition, current smokers presented higher use of biologic drugs compared to nonsmokers. Tobacco exposure and a higher tobacco load were independent predictors of need for maintenance treatment and stenosing phenotype, respectively.

CONCLUSIONS

In the era of early and widespread use of immunosuppressants and biologics, tobacco exposure is an independent predictor of need for maintenance treatment, specifically biologic therapy. The wider use of biologics and immunosuppressants could account for the existence of no major differences in disease behavior and complications between nonsmokers and current smokers.

Review article: Ulcerative colitis, smoking and nicotine therapy

BACKGROUND

Smoking is the best-characterised environmental association of ulcerative colitis (UC). Smoking has been observed to exert protective effects on both the development and progression of UC.

AIMS

To examine the association between UC and smoking, possible pathogenic mechanisms and the potential of nicotine as a therapeutic agent in the treatment of UC.

METHODS

A literature search was conducted through MEDLINE, using the MeSH search terms 'ulcerative colitis' and 'smoking' or 'nicotine'. Relevant articles were identified through manual review. The reference lists of these articles were reviewed to include further appropriate articles.

RESULTS

Ulcerative colitis is less prevalent in smokers. Current smokers with a prior diagnosis of UC are more likely to exhibit milder disease than ex-smokers and nonsmokers. There is conflicting evidence for smokers having reduced rates of hospitalisation, colectomy and need for oral corticosteroids and immunosuppressants to manage their disease. Multiple potential active mediators in smoke may be responsible for these clinical effects, including nicotine and carbon monoxide, but the precise mechanism remains unknown. Nicotine has demonstrated variable efficacy in the induction of remission in UC when compared to placebo and conventional medicines. Despite this, the high frequency of adverse events limits its clinical significance.

CONCLUSIONS

Nicotine's application as a therapeutic treatment in ulcerative colitis is limited. Presently, it may be an option considered only in selected cases of acute ulcerative colitis refractory to conventional treatment options. This review also questions whether nicotine is the active component of smoking that modifies risk and inflammation in ulcerative colitis.

Current and past cigarette smoking significantly increase risk for microscopic colitis

BACKGROUND

Cigarette smoking is an important environmental factor affecting inflammatory bowel disease. The role of smoking has not been rigorously studied in microscopic colitis (MC). The aim of this study was to compare the association of cigarette smoking in individuals with MC compared to a control population without MC.

METHODS

We reviewed the records of patients with a clinical and histologic diagnosis of collagenous colitis (CC) or lymphocytic colitis (LC). Clinical history, including alcohol and smoking status at the time of diagnosis of MC, were reviewed. In this case-control study, age- and gender-matched patients without diarrhea presenting for outpatient colonoscopy served as the control population.

RESULTS

We analyzed a total of 340 patients with MC: 124 with CC and 216 with LC. Overall, any smoking status (former or current) was associated with MC (odds ratio [OR] 2.12, 95% confidence interval [CI]: 1.56-2.88). This risk was more prominent in current smokers (adjusted OR 5.36, 3.81, and 4.37 for CC, LC, and all MC, respectively, 95% CI all greater than 1). The association of smoking was not significantly affected by gender or average alcohol consumption.

CONCLUSIONS

In our study population, cigarette smoking is a risk factor for the development of both forms of microscopic colitis. There were no significant differences between LC and CC, and current smoking and the development of microscopic colitis affected men and women similarly. We feel that these data are sufficient to discuss the potential risks of tobacco use in patients with microscopic colitis.

A prospective study of cigarette smoking and the risk of inflammatory bowel disease in women

OBJECTIVES

Long-term data on the influence of cigarette smoking, especially cessation, on the risk of Crohn's disease (CD) and ulcerative colitis (UC) are limited.

METHODS

We conducted a prospective study of 229,111 women in the Nurses' Health Study (NHS) and Nurses' Health Study II (NHS II). Biennially, we collected updated data on cigarette smoking, other risk factors, and diagnoses of CD or UC confirmed by medical record review.

RESULTS

Over 32 years in NHS and 18 years in NHS II, we documented 336 incident cases of CD and 400 incident cases of UC. Compared with never smokers, the multivariate hazard ratio (HR) of CD was 1.90 (95% confidence interval (CI), 1.42-2.53) among current smokers and 1.35 (95% CI, 1.05-1.73) among former smokers. Increasing pack-years was associated with increasing risk of CD (Ptrend < 0.0001), whereas smoking cessation was associated with an attenuation of risk. By contrast, the multivariate HR of UC was 0.86 (95% CI, 0.61-1.20) among current smokers and 1.56 (95% CI, 1.26-1.93) among former smokers. The risk of UC was significantly increased within 2-5 years of smoking cessation (HR, 3.06; 95% CI, 2.00-4.67) and remained persistently elevated over 20 years.

CONCLUSIONS

Current smoking is associated with an increased risk of CD, but not UC. By contrast, former smoking is associated with an increased risk of UC, with risk persisting over two decades after cessation.

The truth about cigarette smoking and the risk of inflammatory bowel disease

The etiology of inflammatory bowel disease (IBD) is generally believed to be multifactorial in nature involving both genetic and environmental factors. Cigarette smoking has been shown through previous retrospective observational studies to be an environmental factor with both positive and negative influences in IBD. Smoking increases the risk of developing Crohn's disease (CD) but not the risk of ulcerative colitis (UC). Meanwhile smoking cessation increases the risk of a UC flare while CD patients are more likely to show a decrease in disease severity. Unfortunately, these observational studies cannot control for bias the way a randomized controlled trial can, however, they still reveal meaningful truths about smoking and IBD. The study by Higuchi et al. (1) adds to our understanding of the impact of smoking on IBD in several ways. They showed that increasing exposure to smoking is associated with an increased risk of developing CD. They also showed that the risk of UC is highest in the first 2-5 years after smoking cessation but remains elevated for > 20 years. This research also raises several new issues regarding the association between smoking and IBD, which hopefully will be answered through future well-designed observational studies.

Low-dose smoking resumption in ex-smokers with refractory ulcerative colitis

BACKGROUND AND AIM

Ulcerative colitis (UC) is primarily a disease of non-smokers. Ex-smokers may have a more refractory disease course and anecdotal evidence in non-controlled clinical trials have suggested that smoking resumption, or the administration of nicotine, may ameliorate signs and symptoms of UC in ex-smokers. We report outcomes of ex-smokers with refractory UC who resumed low-dose cigarette smoking.

METHODS

17 ex-smokers with refractory UC were identified. Clinical remission was defined as a disease activity index score of 0.

RESULTS

Two out of 17 patients refused the recommendation to resume smoking. Of the 15 patients who resumed smoking, the mean daily number of cigarettes was 8.6. Fourteen out of those 15 patients who resumed smoking were able to maintain prolonged clinical remission off steroids. One out of the 15 patients failed to improve and required oral steroids. Another patient was compelled to quit smoking since he became addicted. His disease flared after maintaining a prolonged remission of 3 years and he eventually underwent surgery. Three out of these 15 patients switched from cigarettes smoking to nicotine compounds and continued to maintain remission.

CONCLUSION

Resumption of low dose smoking in a selected group of ex-smokers with refractory UC may ameliorate signs and symptoms. Quality of life, medication side effects, and smoking risk factors should all be considered and discussed with patients. Smokers should be meticulously followed for compliance with "low-dose" regimen and all associated smoking risks.

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.

Effect of communicating DNA based risk assessments for Crohn's disease on smoking cessation: randomised controlled trial

OBJECTIVE

To test the hypothesis that communicating risk of developing Crohn's disease based on genotype and that stopping smoking can reduce this risk, motivates behaviour change among smokers at familial risk.

DESIGN

Parallel group, cluster randomised controlled trial.

SETTING

Families with Crohn's disease in the United Kingdom.

PARTICIPANTS

497 smokers (mean age 42.6 (SD 14.4) years) who were first degree relatives of probands with Crohn's disease, with outcomes assessed on 209/251 (based on DNA analysis) and 217/246 (standard risk assessment).

INTERVENTION

Communication of risk assessment for Crohn's disease by postal booklet based on family history of the disease and smoking status alone, or with additional DNA analysis for the NOD2 genotype. Participants were then telephoned by a National Health Service Stop Smoking counsellor to review the booklet and deliver brief standard smoking cessation intervention. Calls were tape recorded and a random subsample selected to assess fidelity to the clinical protocol.

MAIN OUTCOME MEASURE

The primary outcome was smoking cessation for 24 hours or longer, assessed at six months.

RESULTS

The proportion of participants stopping smoking for 24 hours or longer did not differ between arms: 35% (73/209) in the DNA arm versus 36% (78/217) in the non-DNA arm (difference -1%, 95% confidence interval -10% to 8%, P=0.83). The proportion making a quit attempt within the DNA arm did not differ between those who were told they had mutations putting them at increased risk (36%), those told they had none (35%), and those in the non-DNA arm (36%).

CONCLUSION

Among relatives of patients with Crohn's disease, feedback of DNA based risk assessments does not motivate behaviour change to reduce risk any more or less than standard risk assessment. These findings accord with those across a range of populations and behaviours. They do not support the promulgation of commercial DNA based tests nor the search for gene variants that confer increased risk of common complex diseases on the basis that they effectively motivate health related behaviour change.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN21633644.

Epidemiology of environmental exposures and human autoimmune diseases: findings from a National Institute of Environmental Health Sciences Expert Panel Workshop

Autoimmune diseases (AID) are a collection of many complex disorders of unknown etiology resulting in immune responses to self-antigens and are thought to result from interactions between genetic and environmental factors. Here we review the epidemiologic evidence for the role of environmental factors in the development of human AID, the conclusions that can be drawn from the existing data, critical knowledge gaps, and research needed to fill these gaps and to resolve uncertainties. We specifically summarize the state of knowledge and our levels of confidence in the role of specific agents in the development of autoimmune diseases, and we define the areas of greatest impact for future investigations. Among our consensus findings we are confident that: 1) crystalline silica exposure can contribute to the development of several AID; 2) solvent exposure can contribute to the development of systemic sclerosis; 3) smoking can contribute to the development of seropositive rheumatoid arthritis; and 4) an inverse association exists between ultraviolet radiation exposure and the risk of development of multiple sclerosis. We suggest that more studies of phenotypes, genotypes, and multiple exposures are needed. Additional knowledge gaps needing investigation include: defining important windows in the timing of exposures and latencies relating to age, developmental state, and hormonal changes; understanding dose-response relationships; and elucidating mechanisms for disease development. Addressing these essential issues will require more resources to support research, particularly of rare AID, but knowledge of the risks conferred by environmental factors in specific genetic contexts could pave the way for prevention of AID in the future.