Lack of association between smoking and Crohn's disease but the usual association with ulcerative colitis in Jewish patients in Israel: a multicenter study

Time Trends of Environmental and Socioeconomic Risk Factors in Patients with Inflammatory Bowel Disease over 40 Years: A Population-Based Inception Cohort 1977-2020

BACKGROUND

Data from population-based studies investigating trends in environmental factors associated with inflammatory bowel disease (IBD) is lacking. We aimed to assess long-term time trends of environmental and socioeconomic factors in IBD patients from a well-defined population-based cohort from Veszprem, Hungary.

METHODS

Patients were included between 1 January 1977, and 31 December 2020. Trends of environmental and socioeconomic factors were evaluated in three periods based on the decade of diagnosis, representing different therapeutic eras: cohort-A,1977-1995; cohort-B,1996-2008 (immunomodulator era); and cohort-C, 2009-2020 (biological era).

RESULTS

A total of 2240 incident patients with IBD were included (ulcerative colitis (UC) 61.2%, male 51.2%, median age at diagnosis: 35 years (IQR 29-49)). Rates of active smoking significantly decreased over time in Crohn's disease (CD): 60.2%, 49.9%, and 38.6% in cohorts A/B/C (p < 0.001). In UC, the rates were low and stable: 15.4%, 15.4%, and 14.5% in cohorts A/B/C (p = 0.981). Oral contraceptive use was more common in CD compared to UC (25.0% vs. 11.6%, p < 0.001). In UC, prevalence of appendectomy before diagnosis decreased over time: 6.4%, 5.5%, and 2.3% in cohorts A/B/C (p = 0.013). No significant changes were found in the socio-geographic characteristics of the IBD population (urban living: UC, 59.8%/64.8%/ 62.5% (p = 0.309) and CD, 62.5%/ 62.0%/ 59.0% (p = 0.636), in cohorts A/B/C). A greater percentage of patients had completed secondary school as the highest education level in later cohorts in both UC (42.9%/50.2%/51.6%, p < 0.001) and CD (49.2%/51.7%/59.5%, p = 0.002). A higher percentage of skilled workers (34.4%/36.2%/38.9%, p = 0.027) was found in UC, but not in CD (p = 0.454).

CONCLUSION

The association between trends of known environmental factors and IBD is complex. Smoking has become less prevalent in CD, but no other major changes occurred in socioeconomic factors over the last four decades that could explain the sharp increase in IBD incidence.

A Mendelian Randomization Analysis Investigates Causal Associations between Inflammatory Bowel Diseases and Variable Risk Factors

The question of whether variable risk factors and various nutrients are causally related to inflammatory bowel diseases (IBDs) has remained unanswered so far. Thus, this study investigated whether genetically predicted risk factors and nutrients play a function in the occurrence of inflammatory bowel diseases, including ulcerative colitis (UC), non-infective colitis (NIC), and Crohn's disease (CD), using Mendelian randomization (MR) analysis. Utilizing the data of genome-wide association studies (GWASs) with 37 exposure factors, we ran Mendelian randomization analyses based on up to 458,109 participants. Univariable and multivariable MR analyses were conducted to determine causal risk factors for IBD diseases. Genetic predisposition to smoking and appendectomy as well as vegetable and fruit intake, breastfeeding, n-3 PUFAs, n-6 PUFAs, vitamin D, total cholesterol, whole-body fat mass, and physical activity were related to the risk of UC (p < 0.05). The effect of lifestyle behaviors on UC was attenuated after correcting for appendectomy. Genetically driven smoking, alcohol consumption, appendectomy, tonsillectomy, blood calcium, tea intake, autoimmune diseases, type 2 diabetes, cesarean delivery, vitamin D deficiency, and antibiotic exposure increased the risk of CD (p < 0.05), while vegetable and fruit intake, breastfeeding, physical activity, blood zinc, and n-3 PUFAs decreased the risk of CD (p < 0.05). Appendectomy, antibiotics, physical activity, blood zinc, n-3 PUFAs, and vegetable fruit intake remained significant predictors in multivariable MR (p < 0.05). Besides smoking, breastfeeding, alcoholic drinks, vegetable and fruit intake, vitamin D, appendectomy, and n-3 PUFAs were associated with NIC (p < 0.05). Smoking, alcoholic drinks, vegetable and fruit intake, vitamin D, appendectomy, and n-3 PUFAs remained significant predictors in multivariable MR (p < 0.05). Our results provide new and comprehensive evidence demonstrating that there are approving causal effects of various risk factors on IBDs. These findings also supply some suggestions for the treatment and prevention of these diseases.

The Association Between Inflammatory Bowel Disease and Exposure to Tobacco Smoking: A Case-Control Study in Qatar

Objective

This research investigated the association between childhood and adulthood tobacco smoking exposure with ulcerative colitis (UC) and Crohn's disease (CD) in Qatar.

Study Design and Setting

In this case-control study, CD and UC cases were matched to controls of the same age and sex. The associations between UC and CD and childhood passive smoking and adulthood active smoking were assessed using conditional multivariable logistic regression.

Results

A total of 89 CD cases, median age of 37 years (IQR 29-47), and 362 UC cases, median age of 35 years (IQR 28-44), and equal numbers of controls were included. After multivariable logistic regression, CD was associated with higher odds of being a current smoker (OR 2.51, 95% CI 0.85-7.37, p=0.095), with weak evidence against the null hypothesis. This association was more pronounced in women, where CD was associated with both adulthood current smoking (OR 42.71, 95% CI, 1.17-1559.57, p=0.041), and childhood smoking exposure (OR 8.23, 95% CI, 1.36-49.66, p=0.021). In males, no associations were observed between CD and the smoking exposures. No associations were observed between UC and both smoking variables.

Conclusion

In Qatar, adulthood tobacco smoking appears to increase the odds of CD. Further, our findings suggest that both childhood and adulthood cigarette smoke exposure may possibly have a detrimental effect on the odds of CD in females but not in males, although further research is needed.

Active and passive smoking and risk of ulcerative colitis: A case-control study in Japan

BACKGROUND AND AIM

Although an inverse relationship between current smoking and the development of ulcerative colitis (UC) has been shown in North America and Europe, evidence is limited in Asian countries, where the incidence of UC is rapidly increasing. This Japanese case-control study examined the association between active and passive smoking and risk of UC.

METHODS

A self-administered questionnaire was used to obtain information on smoking and potential confounding factors in 384 cases with a diagnosis of UC within the past 4 years and 665 controls.

RESULTS

Compared with having never smoked, having ever smoked was associated with an increased risk of UC (adjusted odds ratio [OR] = 1.70, 95% confidence interval [CI]: 1.23-2.37). No association was observed between current smoking and risk of UC, but former smokers had a significant elevation in risk (adjusted OR = 2.40, 95% CI: 1.67-3.45). There was a positive dose-response relationship with pack-years smoked (P for trend = 0.006). Among never smokers, passive smoking exposure at home was significantly associated with an increased risk of UC (adjusted OR = 1.90, 95% CI: 1.30-2.79). A significant dose-response gradient was also observed between pack-years of passive smoking at home and risk of UC (P for trend = 0.0003).

CONCLUSIONS

We confirmed that former smoking elevated the risk of UC, whereas an inverse association between current smoking and the risk of UC did not reach a statistically significant level. Passive smoking may be associated with an increased risk of UC.

Ethnic Differences in the Smoking-related Risk of Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

The association between smoking and inflammatory bowel disease [IBD] relies on old meta-analyses including exclusively non-Jewish White populations. Uncertainty persists regarding the role of smoking in other ethnicities.

METHODS

We systematically searched Medline/PubMed, Embase, and Scopus for studies examining tobacco smoking and the risk of developing IBD, ie, Crohn's disease [CD] or ulcerative colitis [UC]. Two authors independently extracted study data and assessed each study's risk of bias. We examined heterogeneity and small-study effect, and calculated summary estimates using random-effects models. Stratified analyses and meta-regression were employed to study the association between study-level characteristics and effect estimates. The strength of epidemiological evidence was assessed through prespecified criteria.

RESULTS

We synthesised 57 studies examining the smoking-related risk of developing CD and UC. Non-Jewish White smokers were at increased risk of CD (29 studies; relative risk [RR]: 1.95, 95% confidence interval [CI]: 1.69‒2.24; moderate evidence). No association was observed in Asian, Jewish. and Latin-American populations [11 studies; RR: 0.97; 95% CI: 0.83-1.13], with no evidence of heterogeneity across these ethnicities. Smokers were at reduced risk of UC [51 studies; RR: 0.55, 95% CI: 0.48-0.64; weak evidence] irrespectively of ethnicity; however, cohort studies, large studies, and those recently published showed attenuated associations.

CONCLUSIONS

This meta-analysis did not identify any increased risk of CD in smokers in ethnicities other than non-Jewish Whites, and confirmed the protective effect of smoking on UC occurrence. Future research should characterise the genetic background of CD patients across different ethnicities to improve our understanding of the role of smoking in CD pathogenesis.

Passive Smoking Increases the Risk for Intestinal Surgeries in Patients With Crohn's Disease

BACKGROUND

Despite substantial evidence on the negative effect of active smoking, the impact of passive smoking on the course of Crohn's disease (CD) remains largely unclear. Our aim was to assess passive smoking as a risk factor for intestinal surgeries in CD.

METHODS

The study was conducted in a university-based, monocentric cohort of 563 patients with CD. Patients underwent a structured interview on exposure to passive and active smoking. For clinical data, chart review was performed. Response rate was 84%, leaving 471 cases available for analysis. For evaluation of the primary objective, which was the impact of exposure to passive smoking on the risk for intestinal surgery, only never actively smoking patients were included.

RESULTS

Of 169 patients who never smoked actively, 91 patients (54%) were exposed to passive smoking. Exposed patients were more likely to undergo intestinal surgery than nonexposed patients (67% vs 30%; P < 0.001). Multivariate Cox regression analysis revealed that passive smoking was an independent risk factor for intestinal surgeries (hazard ratio, 1.7; 95% CI, 1.04-2.9; P = 0.034) after adjustment for ileal disease at diagnosis (hazard ratio, 2.9; 95% CI, 1.9-4.5; P < 0.001) and stricturing or penetrating behavior at diagnosis (hazard ratio, 1.9; 95% CI, 1.2-3.1; P = 0.01). Passive smoking during childhood was a risk factor for becoming an active smoker in later life (odds ratio, 2.2; 95% CI, 1.5-3.2; P < 0.001).

CONCLUSION

Passive smoking increases the risk for intestinal surgeries in patients with CD.

Patients' perspectives on smoking and inflammatory bowel disease: An online survey in collaboration with European Federation of Crohn's and Ulcerative Colitis Associations

BACKGROUND

Smoking has detrimental effects on Crohn’s disease (CD) activity while data on ulcerative colitis (UC) are conflicting. Little is known about the use and impact of alternative smoking products in inflammatory bowel diseases (IBD).

AIM

To understand the patients’ perceptions of the impact of smoking on their IBD and to assess differences between CD and UC patients.

METHODS

The questionnaire was developed by Philip Morris Products SA in cooperation with European Federation of Crohn's and Ulcerative Colitis Associations. The final survey questionnaire consisted of 41 questions divided in 8 categories: (1) Subject screener; (2) Smoking history; (3) Background information; (4) IBD disease background; (5) Current disease status; (6) Current therapeutics and medications; and (7) Current nicotine/cigarettes use and awareness of the impacts of smoking on IBD. The questionnaire was submitted online from 4^th November 2019 to 11th March 2020 through the European Federation of Crohn's and Ulcerative Colitis Associations website to IBD patients who were current smokers or had a history of smoking.

RESULTS

In total 1050 IBD patients speaking nine languages participated to the survey. Among them, 807 (76.9%) patients declared to have ever smoked or consumed an alternative smoking product, with a higher proportion of current cigarette smokers among CD patients (CD: 63.1% vs UC: 54.1%, P = 0.012). About two-thirds of the participants declared to have ever stopped cigarette smoking and restarted (67.0%), with a significantly higher proportion among UC patients compared to CD patients (73.1% vs 62.0%, P = 0.001). We also found significant differences between CD and UC patients in the awareness of the health consequences of smoking in their disease and in the perceived impact of smoking on disease activity, for both cigarettes and alternative smoking products.

CONCLUSION

This survey found significant differences between CD and UC patients in both awareness and perception of the impact of smoking on their disease. Further efforts should be done to encourage smoking cessation for all IBD patients, including UC patients.

Environmental Risk Factors for Inflammatory Bowel Diseases: An Umbrella Review of Meta-analyses

BACKGROUND & AIMS

Multiple environmental factors have been associated with the development of inflammatory bowel diseases (IBDs). We performed an umbrella review of meta-analyses to summarize available epidemiologic evidence and assess its credibility.

METHODS

We systematically identified and appraised meta-analyses of observational studies examining environmental factors and risk of IBD (Crohn's disease [CD] or ulcerative colitis [UC]). For each meta-analysis, we considered the random effects estimate, its 95% confidence interval, the estimates of heterogeneity, and small-study effects, and we graded the evidence according to prespecified criteria. Methodologic quality was assessed with AMSTAR (ie, A Measurement Tool to Assess Systematic Reviews) 2.

RESULTS

We examined 183 estimates in 53 meta-analyses of 71 environmental factors related to lifestyles and hygiene, surgeries, drug exposures, diet, microorganisms, and vaccinations. We identified 9 factors that increase risk of IBD: smoking (CD), urban living (CD and IBD), appendectomy (CD), tonsillectomy (CD), antibiotic exposure (IBD), oral contraceptive use (IBD), consumption of soft drinks (UC), vitamin D deficiency (IBD), and non-Helicobacter pylori-like enterohepatic Helicobacter species (IBD). We identified 7 factors that reduce risk of IBD: physical activity (CD), breastfeeding (IBD), bed sharing (CD), tea consumption (UC), high levels of folate (IBD), high levels of vitamin D (CD), and H pylori infection (CD, UC, and IBD). Epidemiologic evidence for all of these associations was of high to moderate strength; we identified another 11 factors associated with increased risk and 16 factors associated with reduced risk with weak credibility. Methodologic quality varied considerably among meta-analyses. Several associations were based on findings from retrospective studies, so it is not possible to determine if these are effects of IBD or the results of recall bias.

CONCLUSIONS

In an umbrella review of meta-analyses, we found varying levels of evidence for associations of different environmental factors with risk of IBD. High-quality prospective studies with analyses of samples from patients with recent diagnoses of IBD are needed to determine whether these factors cause or are results of IBD and their pathogenic mechanisms.

Urban-rural environmental exposure during childhood and subsequent risk of inflammatory bowel disease: a meta-analysis

BACKGROUND

The relationship between living conditions in urban and rural areas during childhood and subsequent inflammatory bowel disease (IBD) remains controversial.

AIM

To explore the association between environmental exposures early in life and the subsequent risk of IBD.

METHODS

Literature searches were conducted in the following databases: PubMed, EMBASE, and Conference Proceedings Citation Index. Studies were analyzed separately using rate ratios (RRs) or odds ratios (ORs) with 95% confidence intervals.

RESULTS

The search strategy identified 15 studies. Of these, 9 studies explored the association between urban exposure during childhood and ulcerative colitis (UC), and 12 and 4 studies explored this relationship with Crohn's disease (CD) and IBD, respectively. A meta-analysis showed that the pooled ORs estimated for the case-control studies of UC, CD, and IBD were 1.16 (0.83, 1.61), 1.45 (1.45, 1.85), and 1.34 (1.11, 1.62), respectively. The pooled RR estimated for the cohort studies of CD and IBD was 1.48 (1.17, 1.87). The stratified analysis and meta-regression showed significant relationships between CD and living conditions in case-control studies published during 2010-2017 and in non-European countries (P < 0.05).

CONCLUSIONS

Living conditions during childhood are positively associated with the subsequent development of IBD. Urban living environment is more common among those with CD than UC.

Smoking and Inflammatory Bowel Disease: A Comparison of China, India, and the USA

BACKGROUND

Cigarette smoking is thought to increase the risk of Crohn's disease (CD) and exacerbate the disease course, with opposite roles in ulcerative colitis (UC). However, these findings are from Western populations, and the association between smoking and inflammatory bowel disease (IBD) has not been well studied in Asia.

AIMS

We aimed to compare the prevalence of smoking at diagnosis between IBD cases and controls recruited in China, India, and the USA, and to investigate the impact of smoking on disease outcomes.

METHODS

We recruited IBD cases and controls between 2014 and 2018. All participants completed a questionnaire about demographic characteristics, environmental risk factors and IBD history.

RESULTS

We recruited 337 participants from China, 194 from India, and 645 from the USA. In China, CD cases were less likely than controls to be current smokers (adjusted odds ratio [95% CI] 0.4 [0.2-0.9]). There was no association between current or former smoking and CD in the USA. In China and the USA, UC cases were more likely to be former smokers than controls (China 14.6 [3.3-64.8]; USA 1.8 [1.0-3.3]). In India, both CD and UC had similar current smoking status to controls at diagnosis. Current smoking at diagnosis was significantly associated with greater use of immunosuppressants (4.4 [1.1-18.1]) in CD cases in China.

CONCLUSIONS

We found heterogeneity in the associations of smoking and IBD risk and outcomes between China, India, and the USA. Further study with more adequate sample size and more uniform definition of smoking status is warranted.

Effect of oral tobacco use and smoking on outcomes of Crohn's disease in India

BACKGROUND AND AIM

Smoking has been linked with adverse outcomes in Crohn's disease (CD); however, it is not known whether oral tobacco (OT) use affects disease outcomes in these patients. The study aimed to assess the association between smoking or OT and outcomes in CD.

METHODS

Retrospective analysis was performed on prospectively maintained records of CD patients from 2004 to 2016. The parameters assessed included disease characteristics at baseline (location, behavior, age at onset, perianal disease, and extraintestinal manifestations), course pattern, and outcomes (surgery, hospitalizations, immunomodulator or biologics use, and steroid requirement).

RESULTS

A total of 426 patients were included (mean age: 39.9 years; 59.9% men; median follow up: 71 months). Forty patients were ever-OT users, and 59 were ever-smokers, ever-use being defined as daily use for at least 2 years. OT use was associated with male sex and smoking. Both OT use and smoking had no effect on baseline characteristics, but upper gastrointestinal disease was less common in ever-smokers. Both OT use and smoking did not have any effect on surgery, immunomodulator, and biologic use. Similarly, no association was found between these outcomes and duration, daily, and cumulative exposure to tobacco. Current but not former tobacco use in both smoked (adjusted odds ratio = 2.59 [1.22-5.49]) and OT (adjusted odds ratio = 2.97 [1.03-8.6]) forms increased risk of hospitalizations.

CONCLUSION

Oral tobacco use and smoking had no significant detrimental effect on disease phenotype or medical and surgical requirements in CD in Indian patients, affirming other non-Caucasian studies that found lack of effect of smoking. However, current tobacco use in any form was associated with hospitalization during follow up.

Underestimation of Smoking Rates in an East Asian Population with Crohn's Disease

Background/Aims

The reported rates of current smoking at the time of Crohn’s disease (CD) diagnosis tend to be low in East Asian studies. However, we hypothesized that East Asian patients may be reluctant to disclose their smoking history, likely because of the influence of the Confucian culture.

Methods

We prospectively re-evaluated the smoking status at diagnosis in 1,437 Korean CD patients whose smoking status had been reported in our previous study.

Results

After re-evaluation, the current smokers at diagnosis increased from 388 patients (27.0%) to 445 patients (31.0%), indicating that 12.8% (57 of 445 patients) of the current smokers at diagnosis did not disclose their smoking status at their initial evaluation. The proportion of current smokers at diagnosis who had initially concealed their smoking status was significantly higher among the female patients (29.7%, 11/37) compared with the male patients (11.3%, 46/408) (p<0.005) and among the patients who were ≤18 years old at diagnosis (56.4%, 22/39) compared with the patients >18 years old at diagnosis (8.6%, 35/406) (p<0.001).

Conclusions

Subgroups of Korean CD patients, particularly young patients and female patients, are reluctant to disclose their smoking history. Therefore, the suggestion that smoking is not a risk factor for the development of CD in East Asians should be made with caution.

Environmental Hygiene and Risk of Inflammatory Bowel Diseases: A Systematic Review and Meta-analysis

BACKGROUND

According to the hygiene hypothesis, individuals raised in a sanitary environment have a higher risk of developing inflammatory bowel diseases (IBD). However, results have been inconsistent. We conducted this systematic review of factors related to environmental hygiene and risk of IBD, Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

A systematic search was performed on MEDLINE between 1980 and 2015 to identify studies of the association between IBD and contact with pets and farm animals, number of siblings, bedroom sharing in childhood, and access to personal toilet and hot water. Random- or fixed-effect meta-analyses were performed, and analysis further stratified based on ethnicity of the included cohort.

RESULTS

A total of 29 relevant studies were included. Having a pet (odds ratio [OR], 0.76; 95% confidence interval [CI], 0.63-0.88) and contact with farm animals was inversely associated with risk of IBD (OR, 0.45; 95% CI, 0.31-0.60). However, the strength of association with farm animals was statistically stronger in non-white cohorts (OR, 0.27; 95% CI, 0.02-0.53) than in white cohorts (OR, 0.55; 95% CI, 0.45-0.65) (P = 0.028). Access to toilet (OR, 0.71; 95% CI, 0.56-0.85) and hot water (OR, 0.67; 95% CI, 0.44-0.89) was inversely associated with UC in non-white populations but not whites. Having more than 2 siblings was inversely associated with risk of CD.

CONCLUSIONS

Several factors pertaining to reduced environmental hygiene are inversely associated with risk of IBD. However, underlying ethnicity influences susceptibility to the effect of these factors.

Risk factors for primary sclerosing cholangitis

BACKGROUND & AIMS

Primary sclerosing cholangitis (PSC) is a progressive cholestatic liver disease of unknown cause, but strongly associated with inflammatory bowel disease (IBD). Potential risk factors triggering PSC have never been studied on a population level. The aim of this study was to evaluate smoking, appendectomy, family history and geographical distribution in a population-based cohort of PSC patients, as compared to IBD control patients and healthy controls (HC).

METHODS

For this case-control study 343 PSC patients, 370 IBD controls and 232 HC's living in a geographically defined area in the Netherlands filled-out a questionnaire concerning smoking, appendectomy and family history of IBD and autoimmune liver diseases.

RESULTS

Smoking was associated with a lower risk of developing PSC in PSC-ulcerative colitis (UC) patients (adjusted OR 0.21; 95% CI 0.12-0.34; P < 0.001). Comparable results were found for PSC-Crohn's disease (CD) patients (16% former smokers) compared to CD patients (55% former smokers) (adjusted OR 0.17; 95% CI 0.08-0.39; P < 0.001). Frequency of appendectomy did not differ between PSC and HC, but PSC-UC patients had undergone appendectomy more often than UC patients (13% vs. 6%) (adjusted OR 2.51; 95%CI 1.04-6.07; P = 0.041). We found no association between family history of IBD or autoimmune liver disease and risk of PSC. Degree of urbanization was not associated with PSC incidence.

CONCLUSION

In this large population-based case-control study we confirm that smoking is associated with a lower risk of developing PSC, independent of its protective effect for developing UC. Appendectomy is not associated with the risk of developing PSC.

The Influence of Second-Hand Cigarette Smoke Exposure during Childhood and Active Cigarette Smoking on Crohn's Disease Phenotype Defined by the Montreal Classification Scheme in a Western Cape Population, South Africa

Background

Smoking may worsen the disease outcomes in patients with Crohn’s disease (CD), however the effect of exposure to second-hand cigarette smoke during childhood is unclear. In South Africa, no such literature exists. The aim of this study was to investigate whether disease phenotype, at time of diagnosis of CD, was associated with exposure to second-hand cigarette during childhood and active cigarette smoking habits.

Methods

A cross sectional examination of all consecutive CD patients seen during the period September 2011-January 2013 at 2 large inflammatory bowel disease centers in the Western Cape, South Africa was performed. Data were collected via review of patient case notes, interviewer-administered questionnaire and clinical examination by the attending gastroenterologist. Disease phenotype (behavior and location) was evaluated at time of diagnosis, according to the Montreal Classification scheme. In addition, disease behavior was stratified as ‘complicated’ or ‘uncomplicated’, using predefined definitions. Passive cigarette smoke exposure was evaluated during 3 age intervals: 0–5, 6–10, and 11–18 years.

Results

One hundred and ninety four CD patients were identified. Cigarette smoking during the 6 months prior to, or at time of diagnosis was significantly associated with ileo-colonic (L3) disease (RRR = 3.63; 95%CI, 1.32–9.98, p = 0.012) and ileal (L1) disease (RRR = 3.54; 95%CI, 1.06–11.83, p = 0.040) compared with colonic disease. In smokers, childhood passive cigarette smoke exposure during the 0–5 years age interval was significantly associated with ileo-colonic CD location (RRR = 21.3; 95%CI, 1.16–391.55, p = 0.040). No significant association between smoking habits and disease behavior at diagnosis, whether defined by the Montreal scheme, or stratified as ‘complicated’ vs ‘uncomplicated’, was observed.

Conclusion

Smoking habits were associated with ileo-colonic (L3) and ileal (L1) disease at time of diagnosis in a South African cohort.

Appendectomy and the clinical course of ulcerative colitis: a retrospective cohort study and a nested case-control study from Korea

BACKGROUND AND AIM

Appendectomy protects against the development of ulcerative colitis (UC). However, the relationship between appendectomy and the clinical course of UC is complex, and could be impacted by a number of variables. The aim of this study was to compare the clinical course of UC between appendectomized patients and nonappendectomized patients in Korea.

METHODS

Data on 2648 UC patients were retrieved from the Inflammatory Bowel Disease registry at Asan Medical Center. This retrospective cohort study compared the clinical course of UC in 68 patients who received an appendectomy before their UC diagnosis and 2544 patients who did not receive this procedure. A nested case-control study was also conducted to compare the disease course before and after appendectomy in 36 patients who received this surgery after UC diagnosis. To control for potential confounders, 144 matched controls were retrieved from among 2544 nonappendectomized patients

RESULTS

In the retrospective cohort study, an appendectomy before UC diagnosis demonstrated no influence on disease extent at diagnosis, rates of medication use, proximal disease extension, or colectomy. The 10- and 20-year probabilities of receiving a colectomy were 12.7% and 20.6%, respectively, in appendectomized patients, in comparison with 8.9% and 16.4%, respectively, in nonappendectomized patients (P = 0.81). According to the nested case-control study, an appendectomy after UC diagnosis did not change the subsequent disease course in terms of medication use, proximal disease extension, or hospital admission rate. The adjusted ratio of hospital admissions after appendectomy versus before appendectomy was 1.01 (95% confidence interval = 0.46-2.23; P = 0.97).

CONCLUSIONS

Appendectomies performed before or after UC diagnosis do not affect its clinical course in the Korean population.

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.

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.

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.

Impact of environmental and dietary factors on the course of inflammatory bowel disease

Besides their possible effects on the development of inflammatory bowel disease (IBD), some environmental factors can modulate the clinical course of both ulcerative colitis (UC) and Crohn’s disease (CD). This review is mainly devoted to describing the current knowledge of the impact of some of these factors on the outcome of IBD, with special emphasis on smoking and diet. Although the impact of smoking on the susceptibility to develop CD and UC is firmly established, its influence on the clinical course of both diseases is still debatable. In CD, active smoking is a risk factor for postoperative recurrence. Beyond this clinical setting, smoking cessation seems to be advantageous in those CD patients who were smokers at disease diagnosis, while smoking resumption may be of benefit in ex-smokers with resistant UC. The role of dietary habits on the development of IBD is far from being well established. Also, food intolerances are very frequent, but usually inconsistent among IBD patients, and therefore no general dietary recommendations can be made in these patients. In general, IBD patients should eat a diet as varied as possible. Regarding the possible therapeutic role of some dietary components in IBD, lessons should be drawn from the investigation of the primary therapeutic effect of enteral nutrition in CD. Low-fat diets seem to be particularly useful. Also, some lipid sources, such as olive oil, medium-chain triglycerides, and perhaps omega-3 fatty acids, might have a therapeutic effect. Fermentable fiber may have a role in preventing relapses in inactive UC.

The effect of smoking on intestinal inflammation: what can be learned from animal models?

Epidemiological evidence demonstrates that smoking is the most important environmental risk factor in Crohn's disease while it positively interferes with the disease course of ulcerative colitis. However, the underlying mechanisms through which smoking exerts this divergent effect and affects pathogenesis of inflammatory bowel disease are largely unknown. Animal smoke models are good models to investigate the impact of cigarette smoke on intestinal physiology and inflammation. They enable one to explore the interaction of smoke components and the gut on cellular and molecular level, clarifying how smoking interferes with normal gut function and with disease course in inflammatory conditions. This review describes the currently used animal models for studying the impact of cigarette smoke on the intestinal tract. We first discuss the different methods for simulation of smoking. Furthermore, we focus on the effect of smoke exposure on normal gut physiology and immunology, on experimental (entero)colitis, and on inflammation-induced neoplasia. Based on this current knowledge, a hypothesis is formulated about the mechanisms through which cigarette smoke interferes with the gut in normal and pathological conditions.

Management of Crohn's disease in smokers: is an alternative approach necessary?

Inflammatory bowel disease is a chronic condition with a pathogenic background that involves both genetic and environmental factors. Although important progress has been made regarding the former in the last decade, scarce knowledge is available for the latter. In this sense, smoking remains the most important environmental factor in IBD. Active smoking increases the risk of developing Crohn's disease (CD). Moreover, CD patients who start or continue smoking after disease diagnosis are at risk for poorer outcomes such as higher therapeutic requirements and disease-related complications, as compared to those patients who quit smoking or who never smoked. However, the harmful effect of active smoking is not uniform in all patients or in all clinical scenarios. Interventions designed to facilitate smoking cessation may impact the course of the disease. In this article, the available evidence of the deleterious effects of smoking on CD is reviewed in detail, and alternative therapeutic approaches to CD in smokers are proposed.

Ulcerative colitis in smokers, non-smokers and ex-smokers

Smoking is a major environmental factor that interferes in the establishment and clinical course of ulcerative colitis (UC). Firstly, the risk of smoking status impact in the development of UC is reviewed, showing that current smoking has a protective association with UC. Similarly, being a former smoker is associated with an increased risk of UC. The concept that smoking could have a role in determining the inflammatory bowel disease phenotype is also discussed. Gender may also be considered, as current smoking delays disease onset in men but not in women. No clear conclusions can be driven from the studies trying to clarify whether childhood passive smoking or prenatal smoke exposure have an influence on the development of UC, mainly due to methodology flaws. The influence of smoking on disease course is the second aspect analysed. Some studies show a disease course more benign in smokers that in non-smokers, with lower hospitalizations rates, less flare-ups, lower use of oral steroids and even less risk of proximal extension. This is not verified by some other studies. Similarly, the rate of colectomy does not seem to be determined by the smoking status of the patient. The third issue reviewed is the use of nicotine as a therapeutic agent. The place of nicotine in the treatment of UC is unclear, although it could be useful in selected cases, particularly in recent ex-smokers with moderate but refractory attacks of UC. Finally, the effect of smoking cessation in UC patients is summarised. Given that smoking represents a major worldwide cause of death, for inpatients with UC the risks of smoking far outweigh any possible benefit. Thus, physicians should advise, encourage and assist UC patients who smoke to quit.

The impact of smoking in Crohn's disease: no smoke without fire

Smoking habit is the most widely accepted environmental factor affecting the incidence and disease progression in the inflammatory bowel diseases. The contrasting effects in Crohn's disease (CD) and ulcerative colitis are unexplained. The purpose of this review is to summarise the existing data on the effects of smoking in CD on disease history, recurrence after surgery, effects on drug responses and to review available evidence that carriage of some of the known susceptibility genes may be disproportionate in smokers with CD. The review also highlights potential mechanisms involved and factors that might affect patients' smoking habits. The clinical and scientific implications of the data are discussed.

Smoking and inflammatory bowel diseases: what in smoking alters the course?

Epidemiological studies provide strong evidence to confirm the correlation between cigarette smoking and inflammatory bowel diseases. This relationship is proved to be positive in Crohn's disease and negative in ulcerative colitis. What in smoking alters the course of inflammatory bowel diseases is still a mystery. Different smoking parts have different and may be opponent actions. Smoking has dual effects. Some of its activities are, sometimes, constructive as they are working in an antagonistic manner to the mechanism of the disease, such as reducing rectal blood flow and accordingly less recruitments of inflammatory mediators to the area of inflammation, enhancement of mucosal production, and consequently, strengthening the membranes, and inhibition of pro-inflammatory mediators' liberation and activity in subjects with ulcerative colitis. Yet the outcome of smoking actions may be affected by the existence of other cofactors. Odd factors, such as shortage of zinc in subjects with Crohn's disease, may facilitate liberation of pro-inflammatory mediators and their activities and accordingly exacerbates symptoms.

Prevalence of vitamin D insufficiency in Brazilian adolescents

BACKGROUND/AIMS

Cutaneous sun exposure and dietary vitamin D intake are important determinants of vitamin D status. The objective of the present study was to evaluate the vitamin D status of a group of healthy adolescent students living in Brazil.

METHODS

One hundred and thirty-six adolescents, 64 boys and 72 girls, aged 16-20 years old, living in a rural town in the state of São Paulo, Brazil, participated in this study.

RESULTS

The mean dietary vitamin D intake was 140 (120-156) IU/day [3.5 (3.0-3.9) microg/day]. Only 14.9% of the students met the daily adequate intake recommendation of vitamin D. Only 27.9% practice physical activity outdoors and 17.6% of the adolescents apply sunscreen daily. The mean 25(OH)D concentration was 73.0 (22.0) nmol/l [29.2 (8.8) ng/ml]. Vitamin D insufficiency was observed in 60% of adolescents.

CONCLUSIONS

The present study suggests that even in a sunny climate like Brazil the prevalence of vitamin D insufficiency in adolescents is high. Most likely this is due to low intakes of vitamin D in this group. Due to the limited extent of natural dietary sources of vitamin D, a policy of vitamin D food fortification should be considered in the future, and in the meantime greater use of vitamin D supplements in this population group should be encouraged to provide the increased amounts of this essential nutrient for optimal health.

Familial clustering of Crohn's disease in Israel: prevalence and association with disease severity

BACKGROUND

There is limited data addressing the severity of Crohn's disease (CD) in patients with a family history of inflammatory bowel disease (IBD) compared to sporadic cases.

METHODS

We investigated the familial occurrence of IBD and its correlation with disease behavior in CD patients attending the Israeli IBD Foundation meeting using a structured questionnaire.

RESULTS

The study group consisted of 181 CD patients with a total of 825 1(st) degree relatives. Positive family history for IBD in a 1(st) degree relative was reported in 30 patients (16%). Nine out of the 360 parents (2.5%) had IBD (4 CD, 5 UC). There were 17 siblings with IBD (15 CD, 2 UC) out of 351 (4.8%). Ten out of 114 (8.8%) offsprings had IBD (6 CD, 4 UC). When two siblings were affected, their respective age of disease onset was strikingly concordant (r = 0.76, p = 0.008). There was no difference between sporadic and familial CD patients in the age of disease onset, the location of disease, proportion of smokers or percentage of Ashkenazi origin. Furthermore, similar proportions of sporadic and familial patients underwent intestinal surgery, had penetrating or obstructive complications or were treated by immunomodulators and/or biologics. There was also no difference in the reported percentage of time with active disease or the number of flare-ups.

CONCLUSIONS

The prevalence of familial disease among Jewish CD patients in Israel is at the high range of the rate found in other ethnicities. Having a positive family history of IBD has no impact on the severity of the disease.

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.

Passive smoking and inflammatory bowel disease: a meta-analysis

OBJECTIVES

Active smoking has a well-documented role in the etiology of inflammatory bowel disease (IBD), but the role of passive smoking has been unclear. This meta-analysis examined the relationship between prenatal smoke exposure and childhood passive smoke exposure and the development of IBD.

METHODS

We searched the MEDLINE and EMBASE databases to identify observational studies regarding the relationship between prenatal and/or childhood passive smoke exposure and the development of Crohn's disease (CD) and/or ulcerative colitis (UC). Pooled odds ratios (OR) were calculated for each relationship.

RESULTS

A total of 534 and 699 potential studies were identified from the MEDLINE and EMBASE databases, respectively, of which 13 met all of our inclusion criteria. Overall, we did not observe a positive relationship between childhood passive smoke exposure and CD (OR 1.10, 95% confidence interval [CI] 0.92-1.30) or UC (OR 1.01, 95% CI 0.85-1.20). Likewise, we did not observe an association between prenatal smoke exposure and CD (OR 1.10, 95% CI 0.67-1.80), or prenatal smoke exposure and UC (OR 1.11, 95% CI 0.63-1.97).

CONCLUSIONS

Our meta-analysis suggests that there is not a strong association between childhood passive smoke exposure and the development of CD. We found no evidence that childhood passive smoke exposure exerts a protective effect against UC, as is the case in active smoke exposure. The heterogeneity among the small number of studies limited the ability to draw conclusions about prenatal smoke exposure.

Epidemiology of inflammatory bowel disease in a German twin cohort: results of a nationwide study

BACKGROUND

Genetic predisposition as a cause of inflammatory bowel disease (IBD) has been proven by both family and twin studies and genetic variants associated with the disease have been identified. The aim of our study was to determine the concordance rates for IBD in German twin pairs and to evaluate clinical characteristics of concordant and discordant twin pairs.

METHODS

Patients with IBD were asked to participate and complete a questionnaire that contained questions about zygosity, demographic data, and medical history.

RESULTS

A total of 189 twin pairs in which at least 1 member had IBD were recruited (68 monozygotic and 121 dizygotic pairs). Within monozygotic pairs, 11 out of 31 (35%) were concordant for Crohn's disease (CD) and 6 out of 37 (16%) for ulcerative colitis (UC). Two of the 58 (3%) dizygotic pairs with CD and 1 out of 63 (2%) dizygotic pairs with UC were concordant for the disease. In 14 out of 20 (70%) discordant monozygotic CD pairs and 25 out of 31 (81%) discordant monozygotic pairs with UC, the first-born was affected by IBD. For discordant dizygotic twins, the first in birth order had IBD in 33 out of 56 (59%) pairs with CD and 40 out of 62 (64.5%) pairs with UC.

CONCLUSIONS

This study confirms a stronger genetic influence in CD than in UC. The high preponderance in being affected of the first-born twin and the fact that concordance was only 35% for CD and 16% for UC monozygotic twins highlight the important role of environmental trigger factors.

Smoking in inflammatory bowel diseases: good, bad or ugly?

Smoking is an important environmental factor in inflammatory bowel disease (IBD), having different effects in ulcerative colitis (UC) and Crohn's disease (CD). A recent meta-analysis partially confirmed previous findings that smoking was found to be protective against ulcerative colitis and, after onset of the disease, might improve its course, decreasing the need for colectomy. However, smoking increases the risk of developing CD and worsens its course, increasing the need for steroids, immunosuppressants and re-operations. Smoking cessation aggravates ulcerative colitis and improves CD. Data are however, largely conflictive as well as the potential mechanisms involved in this dual relationship are still unknown. In this review article, the authors review the role of smoking in inflammatory bowel diseases.

Smoking in inflammatory bowel diseases: Good, bad or ugly?

Smoking is an important environmental factor in inflammatory bowel disease (IBD), having different effects in ulcerative colitis (UC) and Crohn’s disease (CD). A recent meta-analysis partially confirmed previous findings that smoking was found to be protective against ulcerative colitis and, after onset of the disease, might improve its course, decreasing the need for colectomy. However, smoking increases the risk of developing Crohn’s disease and worsens its course, increasing the need for steroids, immunosuppressants and re-operations. Smoking cessation aggravates ulcerative colitis and improves Crohn’s disease. Data are however, largely conflictive as well as the potential mechanisms involved in this dual relationship are still unknown. In this review article, the authors review the role of smoking in inflammatory bowel diseases.

Appendectomy, smoking habits and the risk of developing ulcerative colitis: a case control study in private practice setting

OBJECTIVES

The strongest environmental factors identified for ulcerative colitis (UC) are cigarette smoking and appendectomy. However, most studies have been performed using case-controls from hospital-based populations. The purpose of this study was to compare the history of previous appendectomy and smoking habits in a group of patients with UC and a control group, followed by gastroenterologists in private practice.

METHODS

We performed a case control study in which 100 physicians recruited UC-patients and age and sex matched controls. Data were collected during a single visit. Based on a standardized questionnaire, UC patients and controls were divided into never, former or current smokers, and into subjects with or without a previous history of appendectomy.

RESULTS

One hundred and ninety eight age- and sex-matched pairs of UC patients and controls were included. The prevalence of appendectomy in the UC-patients and control group was 12% and 46%, respectively. The pairwise-matched OR of ulcerative colitis for previous appendectomy was 0.10 (95% CI, 0.05-0.21) (P<0.0001). The OR for former and never smokers versus current smokers was 2.40 (95% CI 1.31-4.38) (P=0.004). In UC-patients, the OR of family history of UC compared with controls was 2.80 (95% CI, 1.01-7.77) (P=0.048).

CONCLUSIONS

This case-control study confirmed a strong negative correlation between both appendectomy and tobacco smoking, and ulcerative colitis in patients followed-up by gastroenterological practitioners.

Effect of smoking on inflammatory bowel disease: Is it disease or organ specific?

Smoking is an important environmental factor in inflammatory bowel disease (IBD) with differing effects in ulcerative colitis (UC) and Crohn’s disease (CD). Never smoking and formerly smoking increase the risk of UC, whereas smoking exacerbates the course of CD. The potential mechanisms involved in this dual relationship are yet unknown. A reasonable assumption is that smoking has different effects on the small and large intestine. This assumption is based on animal and human studies that show that the effects of smoking/nicotine on CD and UC depend on the site of inflammation and not on the type of disease.

Risk factors for inflammatory bowel disease in the general population

BACKGROUND

The aetiology of inflammatory bowel disease remains largely unknown.

AIM

We performed a comprehensive assessment of potential risk factors associated with the occurrence of inflammatory bowel disease.

METHODS

We identified a cohort of patients 20-84 years old between 1995 and 1997 registered in the General Practitioner Research Database in the UK. A total of 444 incident cases of IBD were ascertained and validated with the general practitioner. We performed a nested case-control analysis using all cases and a random sample of 10 000 frequency-matched controls.

RESULTS

Incidence rates for ulcerative colitis, Crohn's disease, and indeterminate colitis were 11, 8, and 2 cases per 100 000 person-years, respectively. Among women, we found that long-term users of oral contraceptives were at increased risk of developing UC (OR: 2.35; 95% CI: 0.89-6.22) and CD (OR: 3.15; 95% CI: 1.24-7.99). Similarly, long-term users of HRT had an increased risk of CD (OR: 2.60; 95% CI: 1.04-6.49) but not UC. Current smokers experienced a reduced risk of UC along with an increased risk of CD. Prior appendectomy was associated with a decreased the risk of UC (OR: 0.37; 95% CI: 0.14-1.00).

CONCLUSIONS

Our results support the hypothesis of an increased risk of inflammatory bowel disease associated with oral contraceptives use and suggest a similar effect of hormone replacement therapy on CD. We also confirmed the effects of smoking and appendectomy on inflammatory bowel disease.

Inflammatory bowel disease and smoking: a review of epidemiology, pathophysiology, and therapeutic implications

The relationship between smoking behavior and inflammatory bowel disease (IBD) is complex. While Crohn's disease (CD) is associated with smoking and smoking has detrimental effects on the clinical course of the disease, ulcerative colitis (UC) is largely a disease of nonsmokers and former smokers. Furthermore, cigarette smoking may even result in a beneficial influence on the course of ulcerative colitis. The potential mechanisms involved in this dual relationship include changes in humoral and cellular immunity, cytokine and eicosanoid levels, gut motility, permeability, and blood flow, colonic mucus, and oxygen free radicals. Nicotine is assumed to be the active moiety. The differential therapeutic consequences comprise the cessation of smoking in CD and, so far, clinical trials using nicotine in different forms of application for UC. In this article, we review the relationship between cigarette smoking and IBD, considering epidemiological, pathogenetic, and clinical aspects.

Jejunoileal Crohn's disease: a case-control study

AIMS

Jejunoileitis might be a severe form of Crohn's disease (CD). The aim of the study was to evaluate clinical characteristics, therapeutics modalities and long-term outcome in CD patients with jejunoileitis (CDJI).

METHODS

All patients with CDJI followed in the department of Gastroenterology from 1963 to 1999 were included and compared to matched (on Year of CD diagnosis) CD controls without jejunoileitis. Data were obtained from retrospective review of medical charts.

RESULTS

Eighteen patients with CDJI were compared to 36 matched CD controls. Median follow-up was 7.65 Years in both groups. At time of CDJI diagnosis the following signs were significantly more frequent in patients with jejunoileal CD than in controls: malnutrition (39% vs 3%), pain suggesting obstruction (33% vs 8%), vomiting (28% vs 5%). Patients with CDJI were more frequently male: M/F ratio=2.0/1.1 (P=0.33). Upper digestive involvement (esophagus, stomach and duodenum) (67% vs 36%, P=0.04) and small intestine strictures (61% vs 19%, P=0.06) were more frequent in CDJI. Initial management was more "aggressive" in CDJI than in controls: steroids in 62% vs 30%, azathioprine in 39% vs 3%, total parenteral nutrition in 28% vs 8% and surgery in 33% vs 17%. During follow-up, the need for azathioprine therapy and surgery were more frequent in CDJI than in controls (extensive small bowel resection in two patients). In 10 of 18 patients, jejunoileitis involvement was diagnosed with a median delay of 3.6 Years (range: 0.5-14.5) after CD diagnosis and at time of CD diagnosis in the 8 others; outcome after CDJI diagnosis was similar in these 2 groups.

CONCLUSION

The main revealing signs of jejunoileitis in CD patients are obstruction and malnutrition. Patients with CDJI require more often azathioprine and surgery than CD patients without jejunoileitis. Jejunoileitis is a severe form of CD more frequently complicated by extensive small bowel resection.

Tobacco and IBD: relevance in the understanding of disease mechanisms and clinical practice

Current smoking protects against ulcerative colitis and, after onset of the disease, improves its course, decreasing the need for colectomy. However, smoking increases the risk of developing Crohn's disease and worsens its course, increasing the need for steroids, immunosuppressants and reoperations. Smoking cessation aggravates ulcerative colitis and improves Crohn's disease. The effects of smoking are the sum of contradictory effects of various substances, including nicotine and carbon monoxide, and are modulated by gender, genetic background, disease location and activity, cigarette dose and nicotine concentration. Smokers with ulcerative colitis should not be discouraged from stopping smoking but encouraged to stop, to reduce their risk of cardiopulmonary tobacco-related diseases. In Crohn's disease, smoking cessation has become a major therapeutic goal, particularly in young women and in patients with ileal involvement. A large amount of supportive information, use of nicotine-replacement therapies and antidepressants, and individual counselling might aid the patient in quitting.

Left-sided ulcerative colitis

Left-sided ulcerative colitis is not a distinct entity, but a less extensive form of pancolitis. The epidemiologic and genetic characteristics are thought to be analogous. The rate of colorectal cancer, however, seems to be proportional to the extent of disease. Primary treatment for left-sided disease is topical 5-aminosalicyclic acid (5ASA) agents. In patients who do not respond to topical therapy, oral 5ASA agents of differing delivery methods to the distal bowel can be used. There is much debate pertaining to the clinical superiority of the oral 5ASA agents.

Clinical epidemiology of inflammatory bowel disease: Incidence, prevalence, and environmental influences

Although the incidence and prevalence of ulcerative colitis and Crohn's disease are beginning to stabilize in high-incidence areas such as northern Europe and North America, they continue to rise in low-incidence areas such as southern Europe, Asia, and much of the developing world. As many as 1.4 million persons in the United States and 2.2 million persons in Europe suffer from these diseases. Previously noted racial and ethnic differences seem to be narrowing. Differences in incidence across age, time, and geographic region suggest that environmental factors significantly modify the expression of Crohn's disease and ulcerative colitis. The strongest environmental factors identified are cigarette smoking and appendectomy. Whether other factors such as diet, oral contraceptives, perinatal/childhood infections, or atypical mycobacterial infections play a role in expression of inflammatory bowel disease remains unclear. Additional epidemiologic studies to define better the burden of illness, explore the mechanism of association with environmental factors, and identify new risk factors are needed.

Crohn's disease patients who quit smoking have a reduced risk of reoperation for recurrence

BACKGROUND

Smoking increases the risk of recurrent Crohn's disease (CD).

METHODS

We examined the impact of smoking, quitting smoking, and other factors on reoperation for recurrent CD. We distributed questionnaires to 584 patients from a surgical database whom had undergone a surgical operation for ileocecal CD to assess history of smoking, medical, behavioral, and demographic information.

RESULTS

Two hundred sixty-seven patients completed the questionnaire (46% response). Smokers were more likely to have undergone 1, 2, and 3 reoperations for recurrence at any site (relative incidence rates [RIR] 1.32, 95% confidence interval [CI]: 1.10 to 1.60; RIR 1.55, 95% CI: 1.09 to 2.20; and RIR 1.77, 95% CI: 1.02 to 3.06, respectively) and were more likely to have undergone one reoperation for recurrent ileocecal CD (RIR 1.48, 95% CI: 1.18 to 1.86). Patients who quit smoking were less likely to have undergone 1, 2, and 3 reoperations for recurrence at any site (RIR 0.25, 95% CI: 0.15 to 0.41; RIR 0.30, 95% CI: 0.16 to 0.57; and RIR 0.25, 95% CI: 0.10 to 0.71, respectively) and were less likely to have undergone one reoperation for recurrent ileocecal CD (RIR 0.27, 95% CI: 0.15 to 0.47).

CONCLUSIONS

This study indicates that patients with ileocecal CD who stop smoking reduce the risk of reoperation for recurrent CD.

Clinical and demographic characterization of Jewish Crohn's disease patients in Israel

BACKGROUND

Crohn's disease (CD) is a chronic transmural inflammatory disease of unknown etiology. Genetic background may influence the nature of disease. The Jewish population in Israel is composed of Ashkenazi and Sephardic Jews, who differ in their genetic background. Previous studies have reported that the prevalence of CD in Sephardic Jews is lower than in Ashkenazi Jews; however, no information is available regarding disease characteristics in these patient populations.

GOALS

To assess the demographic and clinical characteristics of CD in Israeli Jewish patients.

STUDY

We studied 189 CD patients who were observed in our department. Demographic and clinical data were collected and analyzed.

RESULTS

Forty-eight percent of the patients had ileum-only disease. Fistulizing disease was more frequently seen in ileocolonic than in ileal ( p= 0.04) or colonic ( p= 0.01) disease, whereas strictures occurred more often in ileal than in colonic disease (22% and 3%, respectively, p= 0.007). No association was found between current smoking and disease severity. Sephardic patients more frequently had extraintestinal disease than did Ashkenazi patients (35% vs. 17%, respectively, = 0.019).

CONCLUSION

Jewish Israeli patients show a predilection for ileum-only disease. Disease severity appears not to be influenced by smoking. These differences in disease behavior may be related to genetic factors.

Crohn disease in patients with familial Mediterranean fever

Crohn disease and familial Mediterranean fever (FMF) are inflammatory diseases characterized by abdominal pain and fever. The concurrence of the 2 diseases (FMF-CD) may pose a challenge to diagnosis and treatment. We undertook the present study to determine the prevalence of Crohn disease in FMF and to characterize FMF-CD patients clinically and genetically. Using a computerized search, the patients of our FMF clinic were screened for a concomitant diagnosis of Crohn disease. Patients and their medical records were thoroughly examined, and their DNA was genotyped for mutations in the MEFV gene. Control groups of ethnically and sex-matched patients suffering from each of the diseases alone, either Crohn disease or FMF, were used for comparison. We identified 7 patients with concomitant Crohn disease and FMF, which is more than the expected prevalence in the general population (p = 0.03). Crohn disease presented at a significantly later age in the FMF-CD group (40.6 +/- 10.0 yr versus 26.2 +/- 11.4 yr; p < 0.004). Disease severity and other characteristics of Crohn disease were comparable to the Crohn disease control group. Contrary to the FMF control group patients, FMF in FMF-CD patients was characterized by a higher attack frequency (p < 0.05) and increased prevalence of amyloidosis (p < 0.02). The overall severity score was similar in both groups. In conclusion, Crohn disease appears to be more prevalent in FMF and presents later than in patients without FMF. FMF in this group of patients shows a higher attack frequency and is more often complicated by amyloidosis.

Chronic nicotine administration differentially alters jejunal and colonic inflammation in interleukin-10 deficient mice

BACKGROUND

Cigarette smoking alters the course of inflammatory bowel disease, is associated with protection against ulcerative colitis, but aggravates or has no effect on Crohn's disease. While the aetiology of this discrepancy remains unclear, differences between location of involvement in ulcerative colitis and Crohn's disease have not been examined in these studies.

AIM

To examine the effects of nicotine administration on the course of jejunitis and colitis in interleukin-10 deficient mice.

METHODS

Male C57/BL10 IL-10 -/- and wild type mice were given nicotine (12.5 microg/ml) in their drinking water at age 12-14 weeks when they had developed clinical signs of inflammatory bowel disease. Gender and age matched control mice received tap water alone. All mice were killed after 2 weeks of treatment. Whole tissue sections of jejunum, proximal and distal colon were separated and examined by macroscopic and histological score. Northern blots were examined for somatostatin, intestinal trefoil factor and mucin-2.

RESULTS

At 14-16 weeks, when the mice were killed, IL-10 -/- untreated control mice developed jejunitis (macroscopic score 1.4 +/- 0.5, microscopic score 2.0 +/- 0.2) and colitis (2.0 +/- 0.2 and 5.9 +/- 0.9, respectively). IL-10 -/- mice treated for 2 weeks with nicotine had significantly reduced colonic scores (1.4 +/- 0.6 and 2.2 +/- 0.15, respectively). In contrast, the jejunum was more severely damaged (2.6 +/- 0.4 and 4.0 +/- 0.3; P = 0.01, respectively). Nicotine significantly increased both somatostatin and intestinal trefoil factor mRNA expression in the colon but not in the jejunum; no effect was noted on mucin-2 or beta-actin mRNA expression.

CONCLUSIONS

(1) Two weeks of nicotine administration leads to contrasting effects on jejunal and colonic inflammation in IL-10 -/- mice. (2) Nicotine ameliorated inflammation in the colon, which was associated with enhanced expression of two protective peptides.