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

Environmental risk factors and Crohn's disease: a population-based, case-control study in Spain

BACKGROUND

The pathogenesis of inflammatory bowel disease probably involves an interaction between genetic and environmental factors: cigarette smoking, appendectomy and oral contraceptives have been the factors most frequently linked to its aetiology

AIM

To analyse the association between known environmental risk factors and development of Crohn's disease in the community of Aragón, Spain.

PATIENTS AND METHODS

A case-control, population-based study has been carried out. All patients diagnosed with Crohn's disease in the community of Aragón from 1st February 1992 to 31st January 1995 were prospectively included. The Lennard Jones criteria were used to define the cases and selected controls among the healthy population matched with patients for age, sex and rural/urban habitat. Statistical analysis included multivariate analysis using conditional logistic regression, testing 38 different models.

RESULTS

A total of 103 patients were diagnosed with Crohn's disease in Aragón from 1st February, 1992 to 31st January, 1995. Of these 62 patients (60.2%) with Crohn's disease were smokers, compared with 42 (40.8%) controls (p<0.001). Cigarette smoking is considered a risk factor for Crohn's disease with an odds ratio of 3.09 (95% confidence interval, 1.58-6.05). After multivariate analysis, the positive association is maintained. A dose-dependent relation could not be demonstrated. No statistical differences (p=0.50) were detected in the analysis of previous appendectomy. Use of oral contraceptive acts as a risk factor with a p=0.048; odds ratio 2, 8, 95% confidence interval: 1.009-7.774; but this association disappears in the multivariate analysis. Eight patients had a family history (3 first degree and 5 second degree relatives) versus none of the controls (p=0.002). Of the variables studied for childhood hygiene none appeared significant.

CONCLUSION

Smoking, family history, and oral contraceptive use, appear as risk factors for developing Crohn's disease in univariate analysis, but only smoking remains significant in all models of multivariate analysis.

Cigarette smoking and celiac sprue: a case-control study

OBJECTIVE

Environmental factors other than gliadin exposure and certain HLA haplotypes may play a role in the pathogenesis of celiac disease. Previous studies have suggested a strong inverse relationship between cigarette smoking and celiac disease. We sought to determine the relationship between celiac disease and cigarette smoking in our patient population.

METHODS

All newly diagnosed adults with biopsy-proven celiac disease evaluated at Mayo Clinic Rochester between January 1, 1993, and June 30, 1998, were identified. Three clinic patients who were matched to each case on geographical area of residence, age, gender, and calendar year of visit served as controls. Smoking information was obtained from a standard medical questionnaire that was completed by all clinic patients at the time of registration. The adjusted odds ratio for celiac disease in current and former smokers relative to nonsmokers was estimated with a matched three-to-one conditional logistic regression model.

RESULTS

A total of 82 adults with biopsy-proven celiac disease were identified. At the time of diagnosis, the proportion of current smokers was 10% in cases and 10% in controls, yielding an adjusted odds ratio of 1.5 (95% CI = 0.5-4.3). In all, 34% of cases were former smokers versus 28% of controls, yielding an odds ratio of 1.6 (95% CI = 0.8-3.2).

CONCLUSION

This case-control study was unable to detect an association between cigarette smoking and celiac disease.

Impact of cessation of smoking on the course of ulcerative colitis

OBJECTIVES

The incidence and severity of ulcerative colitis (UC) are higher in nonsmokers than in smokers. The natural course of UC in smokers who stop smoking is not known. The aim of this study was to determine the impact of cessation of smoking on the course of UC among the cohort of patients regularly seen at our institution.

METHODS

The severity of UC, as judged by the occurrence of flare-ups and the need for systemic steroids, immunosuppressive drugs and colectomy, was determined in 32 patients with UC who stopped smoking after the diagnosis of UC. We compared the period after cessation of smoking (7-yr mean follow-up) with the period between the onset of the disease and the cessation of smoking (9-yr mean duration). The course of UC in this group was compared with that of 32 nonsmokers and 32 continuing smokers matched for sex, age, and age at onset.

RESULTS

In patients who quit, cessation of smoking was followed by an increase in the rate of years with active disease (p < 0.01), years with hospitalization (p < 0.05) and years with major medical therapy (oral steroids, intravenous steroids, and azathioprine, p < 0.01). After cessation of smoking, the rate of years with immunosuppressive therapy was significantly greater in ex-smokers and nonsmokers than in continuing smokers (p < 0.01). The risk of colectomy in ex-smokers after smoking cessation was similar to that of nonsmokers and continuing smokers.

CONCLUSIONS

In smokers with UC who stop smoking, the severity of the disease increases after smoking cessation, with an increase in the disease activity and the need for hospital admission and major medical therapy. In addition, the need for azathioprine therapy becomes similar to that of nonsmokers.

Attitudes toward smoking and smoking behaviors of patients with Crohn's disease

OBJECTIVE

To examine the smoking behaviors of people with Crohn's disease. In active smokers, we measured their willingness to quit, their degree of nicotine dependence, and the proportion that made a quit attempt within 6 months to determine if they were refractory to smoking cessation in comparison to the general population. We also examined factors that were important in their decision to smoke.

METHODS

We conducted a cross-sectional survey of out-patients, supplemented by telephone interviews and a 6-month follow-up questionnaire of active smokers. Measures included disease activity, current smoking behaviors, intentions (stage of change), Fagerstrom Test for Nicotine Dependence, and factors related to their decision to smoke (decisional balance).

RESULTS

The questionnaire was completed by 115 patients (78% response rate). Forty percent were active smokers. Of active smokers, 59% were considering quitting within the next 6 months, and of these, 15% were planning on quitting within the next 30 days. Those with moderate disease activity were more likely to be considering quitting than those with mild or severe activity. Nicotine dependence was rated as high in 33% and as moderate in 43%. Factors unrelated to Crohn's disease were more important in their decision to smoke than were Crohn's disease-related factors. After 6 months, 23% had made an attempt to quit and this attempt was strongly associated with their stated intentions at the baseline questionnaire. Two of three patients who had recently quit at baseline had resumed smoking.

CONCLUSION

When compared to similar data for the general population, patients with Crohn's disease are no more refractory to smoking cessation.

Smoking cessation and the course of Crohn's disease: an intervention study

BACKGROUND AND AIMS

To evaluate the benefit of smoking cessation in individuals with Crohn's disease, we performed an intervention study in a large cohort of smokers with the disease.

METHODS

Repeated counseling to stop smoking, with easy access to a smoking cessation program, was given to 474 consecutive smokers with Crohn's disease. Patients who stopped smoking for more than 1 year (quitters) were included in a prospective follow-up study, which compared disease course and therapeutic needs with 2 control groups, continuing smokers and nonsmokers, paired for age, gender, disease location, and activity.

RESULTS

There were 59 quitters (12%). Predictors of quitting were the physician, previous intestinal surgery, high socioeconomic status, and in women, oral contraceptive use. During a median follow-up of 29 months (1-54 months), the risk of flare-up in quitters did not differ from that in nonsmokers and was less than in continuing smokers (P < 0.001). Need for steroids and for introduction or reinforcement of immunosuppressive therapy, respectively, were similar in quitters and nonsmokers and increased in continuing smokers. The risk of surgery was not significantly different in the 3 groups.

CONCLUSIONS

Patients with Crohn's disease who stop smoking for more than 1 year have a more benign disease course than if they had never smoked.

A critical review of epidemiological studies in inflammatory bowel disease

This review addresses the difficulty in interpreting the results of epidemiological studies in IBD and in making meaningful comparisons between studies. Both ulcerative colitis and Crohn disease appear to be more common in some industrialized countries such as Scandinavia, United Kingdom, North America and less common in Central and Southern Europe, Asia and Africa. Given data showing an increased incidence of ulcerative colitis in the United Kingdom, it is crucial that more studies be conducted in developing countries. While the incidence of Crohn disease has increased strikingly in many areas, the incidence of ulcerative colitis has remained fairly stable in most. This could be due to the rising number of community-based studies, as well as the improved accuracy in diagnosing Crohn disease. Although, the incidence of IBD among Blacks in Africa is low, infection rates are high, life expectancy is lower than in developed countries. Data from the USA suggest that rates are similar in Afro-American and Caucasian populations. Rates for Jewish populations may be slightly higher than in non-Jewish populations but this also varies geographically. Careful attention to genetic, environmental, and socioeconomic factors must be accounted for in these studies. There is no strong evidence to support that IBD is more common in urban than in rural settings and migration towards more accessible health care has not been adequately addressed. Recent epidemiological studies suggest that mortality rates for IBD are similar to that of the general population for the majority of patients. However, older patients with IBD and newly diagnosed cases with severe diseases are at increased risk of dying. Epidemiological studies remain important in assisting with health policy planning and in hypothesis testing of etiological factors. As better diagnostic techniques become widely available and public health registries are increasingly used, it is possible that geographic differences will diminish. International collaborative studies will be better equipped to answer research questions addressing risk factors and disease natural history. We have summarized in Table V the essential criteria to conduct a sound epidemiological study, which would permit future testing of hypotheses among different populations.

Nitric oxide mediates a therapeutic effect of nicotine in ulcerative colitis

BACKGROUND

Ulcerative colitis is a condition of nonsmokers in which nicotine is of therapeutic benefit.

AIMS

To examine the in vitro effect of nicotine on colonic smooth muscle activity and the role of nitric oxide (NO) as a mediator.

METHODS

Nicotine, 1-10 microM, was administered to strips of circular muscle from the distal sigmoid colon of 9 patients with active ulcerative colitis and 18 with colorectal cancer. The effect of electrical field stimulation (EFS) was examined before nicotine was added. Finally L-NAME, a NO synthetase inhibitor, was added before nicotine was administered again.

RESULTS

Muscle strips developed similar spontaneous resting tone. In response to EFS, ulcerative colitis tissue developed lower tensions than the controls. Nicotine significantly reduced the resting tone and peak tension after EFS, with a greater effect in controls. With L-NAME, peak tensions were increased more in ulcerative colitis than controls, and nicotine produced a much smaller reduction.

CONCLUSIONS

Nicotine reduces circular muscle activity, predominantly through the release of nitric oxide-this appears to be 'up-regulated' in active ulcerative colitis. These findings may explain some of the therapeutic benefit from nicotine (and smoking) in ulcerative colitis and may account for the colonic motor dysfunction in active disease.

Advances in inflammatory bowel disease

Optimal management of patients with IBD requires a multidisciplinary approach involving primary care physicians, gastroenterologists, surgeons, radiologists, and nutritionists. The rapidly evolving medical armamentarium promises better quality of life for patients afflicted with these complex, chronic diseases. It is expected that future development of biologic agents will add to the therapeutic options, although it may complicate treatment algorithms. Surgical advancements, particularly in ileoanal anastomosis and bowel preservation by strictureplasty, have improved outcome dramatically. The focus on development of new therapies and refinement of older ones demands a constant attention to the latest peer-reviewed literature and that the clinician keep abreast of the various advancements that have been summarized here.

Medical treatment: does it influence the natural course of inflammatory bowel disease?

It is difficult to predict the clinical course of inflammatory bowel disease (IBD). Moderately sick Crohn's disease (CD) patients and patients with distal ulcerative colitis (UC) may get better even without medical or surgical treatment. Once better, they may continue in remission even without treatment. If they are not treated, there are several factors that predict whether they will maintain remission. Most patients will probably alternate between remission and relapse, with 10% having a relapse-free course after 10 years, and only 1% having a continuously active course. Frequent relapses initially are associated with active disease later on, but the disease activity course is independent of the response to the initial medical treatment. There is a cumulative frequency of operation of 50-80% and of reoperation of 33% in CD, which suggests that CD has a more serious course than UC. In UC, the overall probability of surgery is 33% for pancolitis and 10% for proctitis within 5 years of diagnosis, and the majority of patients are operated on within the first few years. Maintenance treatment with sulphasalazine (SASP) and 5-aminosalicylic acid (5-ASA) in UC has reduced relapse rates to about half over a 1-year follow-up period. The use of 5-ASA for maintenance of CD has been shown to result in only a modest therapeutic gain, while azathioprine and 6-mercaptopurine (6-MP) improve the relapse frequency for at least 3 years whilst on treatment. Changes in disease distribution in UC are part of the natural course of the disease, which should have implications for medical treatment strategies, and affects the risk of colectomy and colonic cancer. Certain enviromental factors are thought to determine disease activity and disease outcome in UC and CD. Patient compliance with prescribed medication and clinical check-ups must be considered another non-specific variable affecting the clinical outcome. IBD frequently requires potent medication with side effects that limit patients' acceptance. Such patients often resort to medicinal herbs, acupuncture, and homeopathy, which may alter the expected course.

Changes in the incidence of inflammatory bowel disease: what does it mean?

A sharp rise in the incidence of inflammatory bowel disease (IBD) has been observed in the western world since the early 1950s. The increase in the incidence of ulcerative colitis preceded the increase in the incidence of Crohn's disease by about 10-15 years. In high-incidence areas, a female preponderance at a young age (20-40 years) is observed in Crohn's disease, whereas in ulcerative colitis male incidence is still high at older ages. IBD is more common in the developed world than in the developing world and, in both the United States and Europe, a north-south incidence gradient has been reported, with IBD more common in the north than in the south. There are also indications that, in typically low-incidence areas, more cases are being seen lately. At present, IBD is rather common in western Europe, affecting 0.5-1.0% of the population during their lifetime. It will be interesting to follow these temporal trends in the coming years, as they may teach us more about the role of environmental factors in the pathogenesis of IBD.

Role of smoking in inflammatory bowel disease: implications for therapy

The relationship between smoking and inflammatory bowel disease is now firmly established but remains a source of confusion among both patients and doctors. It is negatively associated with ulcerative colitis but positively associated with Crohn's disease. In addition, it has opposite influences on the clinical course of the two conditions with benefit in ulcerative colitis but a detrimental effect in Crohn's disease. These differences have been the subject of much interest and scrutiny with the hope that they may offer some insight into the pathogenesis of the two conditions and possibly lead to alternative therapeutic options. Nicotine is probably the principal active ingredient in smoking responsible for the association; trials have shown it to be of some benefit in ulcerative colitis, but further research is required to establish its therapeutic role, and the relevant mechanisms responsible for its action. In this article, we review the role of smoking in inflammatory bowel disease and its implication for therapy.

Stress and exacerbation in ulcerative colitis: a prospective study of patients enrolled in remission

OBJECTIVE

We sought to determine whether psychosocial factors influence the course of ulcerative colitis, hypothesizing that high perceived stress among patients with inactive disease will increase the risk of subsequent exacerbation.

METHODS

Sixty-two patients with known ulcerative colitis were enrolled into a prospective cohort study while in clinical remission. Their perceived stress, depressive symptoms, and stressful life events were followed, along with potential confounders, for up to 45 months; exacerbation status was monitored for up to 68 months.

RESULTS

The 27 patients who experienced an exacerbation were compared with those who remained in remission. Having a score in the upper tertile on the long-term (past 2 yr) baseline Perceived Stress Questionnaire significantly increased the actuarial risk of exacerbation (hazards ratio = 2.8, 95% confidence interval 1.1-7.2). At any given study visit, high long-term stress tripled the risk of exacerbation during the next 8 months (risk for the three tertiles, 8.3%, 16.7%, and 26.2%, p = 0.02). Shorter sleep time, briefer remission, histological activity, and use of nonsteroidal antiinflammatory drugs, antibiotics, or oral contraceptives also increased the medium- and/or long-term risk of exacerbation, but adjustment for these variables did not eliminate the associations with stress. Exacerbation was not associated with stressful life events, depressive symptoms, short-term (past month) perceived stress, smoking, disease extent or duration, or severity of recent course.

CONCLUSIONS

Short-term stress does not trigger exacerbation in ulcerative colitis, but long-term perceived stress increases the risk of exacerbation over a period of months to years.

Smoking and disease recurrence after operation for Crohn's disease

BACKGROUND

There is increasing speculation about the role of smoking in the pathogenesis of inflammatory bowel diseases. The purpose of this study is to review the impact of smoking on disease recurrence after operation for Crohn's disease.

METHODS

A Medline-based literature review (1966-1999) was carried out; ten studies examined the relationship between smoking and disease recurrence after operation.

RESULTS

Approximately half of the patients were smokers at the time of operation. In most studies smoking significantly increased the risk of postoperative disease recurrence. Smokers had an approximately twofold increased risk of recurrence compared with non-smokers and the effect of smoking was dose dependent. The increased risk of recurrence among smokers was more prominent in women than in men, and a longer duration of smoking increased the risk of recurrence. Ex-smokers had a similar recurrence rate to non-smokers and giving up smoking soon after operation was associated with a lower probability of recurrence.

CONCLUSION

Smoking significantly increases the risk of recurrence of disease after operation for Crohn's disease, especially in women and heavy smokers. Encouraging patients to stop smoking is an important part of the management of Crohn's disease.

Helping patients with Crohn's disease quit smoking

Smoking is not only a risk factor for Crohn's disease, but ongoing smoking is associated with a poorer disease course. Therefore, smoking cessation should be an important treatment strategy for Crohn's disease patients who smoke tobacco. Recent improvements in understanding how people quit smoking and the development of pharmacological interventions, such as nicotine patches and bupropion, have improved cessation rates. In this article, we first briefly review the evidence supporting the adverse effects of smoking on the disease course. We next review the current understanding of how people change addictive behaviors, such as smoking. We then describe how the gastroenterologist can aid the patient with Crohn's disease to quit smoking, including appropriate and brief counseling strategies and the use of adjunctive treatments. Given the improvements in smoking cessation strategies, all patients with Crohn's disease should be strongly advised to quit smoking and be aided in doing so.

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

OBJECTIVE

The association between smoking and inflammatory bowel disease (IBD) is well established, but data in Jewish patients in Israel were discrepant. The aim of this study was to examine the smoking habits of Jewish IBD patients in Israel in a large scale, multicenter study.

METHODS

Patients with established IBD aged 18-70 yr were interviewed in relation to smoking and other habits. Two controls (one clinic and one neighborhood control matched by age, sex, community group, and education) were sought for each subject.

RESULTS

A total of 534 patients (273 ulcerative colitis [UC], and 261 Crohn's disease [CD]), along with 478 clinic controls and 430 neighborhood controls, were interviewed. There was no significant difference in the smoking habits between CD patients and their controls. Of patients with CD, 24.5% were current smokers, as compared to 19.9% of clinic controls and 25.2% of neighborhood controls (NS). The odds ratio for CD in current smokers was 1.30 (95% confidence interval 0.85-1.99) versus clinic controls, and 0.96 (0.63-1.46) versus neighborhood controls. There were also no significant differences in the proportion of ex-smokers between the groups. Only 12.9% of UC patients were current smokers versus 21.9. % Clinic controls, and 26.4% community controls (p<0.005). The proportions of ex-smokers were higher in UC patients 29.7% versus 25.9%, and 19.5% in their respective controls (p<0.001 vs. community controls). No significant differences were found in the proportions of never-smokers between IBD patients and controls. All the above trends were similar in four different parts of the country. The proportion of current smokers in UC decreased with the extent of disease (19.7% in proctitis, 13.6% in left-sided, and 4.5% in total colitis) (p<0.05). Patients with UC were more likely to be light smokers(1-10 cigarettes/day), whereas patients with CD were more likely to be moderate smokers (11-20 cigarettes/day) in comparison to their controls.

CONCLUSIONS

The lack of association between smoking and CD has now been established in Jewish patients in Israel. The association was found in UC. The stronger genetic tendency in CD may contribute to this discrepancy.

Effects of current and former cigarette smoking on the clinical course of Crohn's disease

BACKGROUND

Cigarette smoking is associated with a more severe course of Crohn's disease, but individual factors determining this effect are poorly known and it is not clear whether smoking cessation is associated with an improvement in the disease activity.

AIM

To assess the factors determining the harmful effect of smoking in individuals with Crohn's disease.

METHODS

A total of 622 consecutive patients with Crohn's disease and Crohn's disease activity index <200 were enrolled in a prospective 12-18 month cohort study. Patients were classified as current smokers, former smokers, or non-smokers. Alcohol consumption, oral contraceptive use, body mass index, and blood lipid levels were also recorded. The main outcome measure was the rate of flare-up.

RESULTS

A total of 139 current smokers (46%) developed a flare-up, vs. 79 non-smokers (30%) and 13 former smokers (23%). The relative risk of flare-up adjusted for confounding factors was 1.35 (1.03-1.76) in current smokers. This risk was increased in patients with previously inactive disease and in those who had no colonic lesions. It became significant above a threshold of 15 cigarettes per day. Former smokers behaved like non-smokers. Obesity, dyslipidaemia, and alcohol consumption had no significant effect.

CONCLUSIONS

Current smoking, particularly heavy smoking, markedly increases the risk of flare-up in Crohn's disease. Former smokers have a risk similar to that of non-smokers.

An oral formulation of nicotine for release and absorption in the colon: its development and pharmacokinetics

AIMS

Ulcerative colitis is predominantly a disease of nonsmokers and transdermal nicotine has therapeutic value in active disease; however side-effects are troublesome. The aim of this study was to develop an oral formulation of nicotine which would be slowly released in the colon over 6 h, and to examine its pharmacokinetic profile in 12 healthy volunteers, with measurements of serum nicotine and cotinine, its principal metabolite.

METHODS

Nicotine was combined with a polyacrylic carbomer, Carbopol 974P which was incorporated into 13 different vehicles and their release profiles examined in vitro. The polyglycolized glyceride, Gelucire 50/13, was chosen for subsequent kinetic studies because it consistently produced a suitable release pattern which was linear. Capsules containing 3 mg nicotine, combined with carbomer in Gelucire 50/13, were coated with an acrylic resin Eudragit L; this ensured the capsule would remain intact until the ileum. On 2 separate days, 6 and 15 mg nicotine, contained in 2 and 5 capsules, respectively, were administered to 12 subjects, all nonsmokers, mean age 28 years. Serial blood measurements were taken for 36 h, serum nicotine and cotinine concentrations were measured by gas liquid chromatography.

RESULTS

There was considerable intersubject variability in the nicotine and cotinine values. Plasma nicotine levels began to rise about 4 h after ingestion of the capsules, corresponding with the oro-caecal transit time. Cmax nicotine values were 2.2 and 5 ng ml-1, obtained 7 h after the ingestion of 6 and 15 mg, respectively, of the formulation. The corresponding Cmax values for cotinine were 37 and 94.4 ng ml-1, occurring after 9-10 h. The mean for elimination half-lives in the 24 studies, including the 6 and 15 mg doses, for nicotine were 4.3+/-2.7 h and for cotinine 16.8+/-7.5 h. With 6 mg nicotine-carbomer, only 1 of 12 volunteers had possible side-effects, but with the 15 mg dose 11 out of the 12 reported adverse effects which were systemic or gastrointestinal in nature-their timing corresponded with peak serum concentrations of nicotine.

CONCLUSIONS

An oral formulation of nicotine has been developed; in the ileum and colon, this becomes available for slow linear release over 6 h and delivers high concentrations of nicotine for topical effect on the colon. 6 mg Nicotine was well tolerated, whilst 15 mg gave both systemic and gastrointestinal side-effects. High concentrations of topical nicotine in the colon are achieved with relatively low systemic bioavailablity-reflected by the Cmax and AUC values for nicotine. This, or comparable formulations, may be of therapeutic value in ulcerative colitis.

Transdermal nicotine decreases mucosal IL-8 expression but has no effect on mucin gene expression in ulcerative colitis

Our goal was to determine the effect of transdermal nicotine on cytokine and mucin gene transcription in ulcerative colitis (UC). Sixty-four nonsmoking patients with active UC were randomly assigned to transdermal nicotine (maximum dose 22 mg/day) or placebo for 4 weeks. Clinical assessment and colonic mucosal biopsies were obtained at entry and after 4 weeks. Inflammatory and immunoregulatory cytokines were assessed by qualitative reverse transcriptase-polymerase chain reaction (RT-PCR). Based on this initial screen. IL-8 mRNA levels were measured by RT-competitive PCR. MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, and MUC6 mRNA concentrations were measured by quantitative dot blot analysis. Cytokine mRNA expression, except for IL-8, was similar in all patients. IL-8 mRNA levels were significantly decreased in the colonic mucosa of nicotine-treated patients who improved (p = 0.04). IL-8 mRNA values were similar before and after treatment in nonresponding nicotine-treated patients and in all placebo-treated patients. Mucin gene expression was similar in all patient groups. Beneficial effects of transdermal nicotine in active UC may result from decrease of IL-8 expression at the transcriptional level. Transdermal nicotine has no effect on mucin gene transcription.

Epidemiology and the natural course of inflammatory bowel disease

Ulcerative colitis and Crohn's disease are inflammatory disorders of the gastrointestinal tract that are distributed unevenly within populations and throughout the world. Although the exact causes of inflammatory bowel disease (IBD) remain unknown, study of the epidemiology of IBD has provided insight into pathogenesis. This article examines the geographic, ethnic, and other trends of IBD; risk factors (including genetic and environmental); and the natural history of IBD.

Nicotine therapy for ulcerative colitis: a review of rationale, mechanisms, pharmacology, and clinical results

Smoking is protective against developing ulcerative colitis. Nicotine may be the cause of this protective effect. Controlled trials have demonstrated efficacy of transdermal nicotine for active ulcerative colitis. Side effects observed with transdermal nicotine include contact dermatitis, nausea, and lightheadedness. Topical administration of nicotine to the colon reduces nicotine blood concentrations and side effects, and may be of clinical benefit.

Inflammatory bowel disease

Although ulcerative colitis and Crohn's disease are relatively uncommon disorders, most primary care practices include a number of individuals with these diagnoses. Much of the initial evaluation and long-term care of these patients is managed or coordinated by their primary care physicians. A familiarity with current principles of diagnosis and treatment is essential. Ulcerative colitis and Crohn's disease are related, immunologically mediated disorders of unknown cause. Both are characterized by chronic relapsing courses, frequent need for surgical intervention, and increased colorectal cancer risk. Significant differences are seen between these two inflammatory bowel disease syndromes, in their histopathologic features, clinical manifestations, and response to treatment. This review focuses on the colorectal manifestations of inflammatory bowel disease, emphasizing clinical presentation, approach to diagnosis, medical and surgical management, and long-term prognosis.

Clinical status of ulcerative colitis in patients who smoke

OBJECTIVES

Ulcerative colitis (UC) is largely a disease of nonsmokers. There are few patients who are current smokers, but we have identified a group and reviewed their clinical status, disease activity, and nicotine exposure to examine whether they remain well controlled while smoking.

METHODS

Fifty-one patients from three centers with verified UC were reviewed.

RESULTS

Thirty of the group were men; mean age 50 yr, with a mean age of onset of 37 yr. Twenty-two patients had proctosigmoid disease, 12 involvement of left colon, and 17 total colitis. All were current smokers; 41 were cigarette smokers averaging 17 daily. At the onset of colitis 30 were nonsmokers, 25 of them were ex-smokers and 19 developed colitis within 2 yr of stopping smoking. Twenty-eight believed smoking improved disease activity and none felt smoking had a detrimental effect on their UC. Eleven were receiving no medication for UC, 40 were receiving 5-ASA (5-aminosalicylic acid) preparations, and only two took oral steroids. All were in clinical remission, with the exception of one patient; mean St. Marks score was 1.5, out of a possible total of 22. Sigmoidoscopic grades were inactive in all patients except three. Histological assessment showed significant activity in only five. Median serum nicotine was 8 ng/ml (range, 0.4-24.4), median serum cotinine 180 ng/ml (range, 20-453), with corresponding salivary cotinine of 255 ng/ml (range, 34-683). Median rise in nicotine 2 min after a cigarette in 35 patients was 12.1 ng/ml (range, 0.4-44).

CONCLUSIONS

Because most current smokers with UC have inactive disease, smoking may contribute to the clinical remission in these patients.

Transdermal nicotine inhibits interleukin 2 synthesis by mononuclear cells derived from healthy volunteers

BACKGROUND

Smoking has either a beneficial or harmful effect on the course and recurrence of ulcerative colitis (UC) and Crohn's disease respectively. Transdermal application of nicotine had similar effects in UC and therefore was considered to be an effective basic drug that could be further developed in the search for new compounds in the treatment of acute exacerbations of corticosteroid-resistant UC. To clarify the hypothesis that nicotine exerts its anti-inflammatory effect in UC through selective inhibition of T-cell-derived cytokine synthesis, we studied in vivo effects of nicotine on cytokine production by human non-adherent mononuclear cells isolated from peripheral blood in a randomized, double-blind, placebo-controlled trial.

METHODS

Healthy non-smoking volunteers applied for 2 weeks of nicotine patches (n = 12) with incremental doses of nicotine during the first week to achieve a maintenance dose of 15 mg per day, or placebo (n = 12). Blood was obtained before treatment and 1, 2, 3 and 6 weeks after the start of treatment. Cells were cultured in the absence or presence of phytohaemagglutinin for 48 h, and total amounts of interleukin 2 (IL-2), IL-4, IL-10, IL-13, interferon gamma (IFN-gamma) and tumour necrosis factor alpha (TNF-alpha) were measured.

RESULTS

Transdermal nicotine caused a significant inhibition of IL-2 after 2 weeks' treatment compared with the placebo group. In addition, a diminished production of IL-10 and TNF-alpha in comparison with day 0 was observed.

CONCLUSION

The beneficial effect of transdermal nicotine in ulcerative colitis may be mediated by a selective inhibition of the IL-2 production by mucosal mononuclear cells, which could result in diminished cell proliferation and consequently a reduction in the inflammatory process.

Autoimmune (Hashimoto's) thyroiditis associated with Crohn's disease

We report the occurrence of autoimmune (Hashimoto's) thyroiditis in three patients with Crohn's disease. Previously, thyroid disease has been described only in association with ulcerative colitis. We review the pertinent literature on thyroid disease in inflammatory bowel disease (IBD) and suggest that this association supports the hypothesis that autoimmunity is involved in the pathogenesis of IBD. Early diagnosis and treatment of thyroid dysfunction in patients with IBD is desirable because thyroid dysfunction worsens the symptoms and course of IBD.

Inflammatory bowel disease and smoking--a review

The relationship between smoking and inflammatory bowel disease is a curious but well-established one. It is negatively associated with ulcerative colitis but positively associated with Crohn's disease. It also has opposite influences on the clinical course of the two conditions with possible beneficial effect in ulcerative colitis and detrimental effect in Crohn's disease. The diametrically "opposite" relationship of smoking status with the two conditions has been the subject of much interest in the hope that it may reveal pathogenic mechanisms responsible for the two conditions and possibly offer the key to alternative therapeutic options. Nicotine may be the principal agent in smoking responsible for the association; trials have shown it to be of some benefit in ulcerative colitis, but further research is required to establish its therapeutic role and possible mechanisms of action. In this article, we review the historical, clinical, and therapeutic aspects of the association between smoking and inflammatory bowel disease.

Smoking and nicotine in inflammatory bowel disease: good or bad for cytokines?

Smoking has either a beneficial or harmful effect on the course and recurrence of ulcerative colitis and Crohn's disease respectively. Transdermal application of nicotine had similar effects in ulcerative colitis and therefore was considered to be an effective basic drug which could be further developed in the search for new compounds in the treatment of acute exacerbations of corticosteroid resistant ulcerative colitis. In this communication the short-term use of nicotine in ulcerative colitis is reviewed.

The effect of mesalamine and nicotine in the treatment of inflammatory bowel disease

OBJECTIVE

To characterize the usefulness of mesalamine and nicotine in the treatment of active ulcerative colitis and inactive Crohn's disease.

DATA SOURCES

Citations were selected from the MEDLINE database. Only those involving human subjects, inflammatory bowel disease, and available in English were selected.

STUDY SELECTION

Selection criteria of clinical trials and review articles assessing the effects of mesalamine and nicotine in active ulcerative colitis or inactive Crohn's disease and the utility of reducing steroid dependence or relapse rate. Less than 20% of the articles identified met the selection criteria.

DATA SYNTHESIS

In patients with inactive Crohn's disease, mesalamine 2 g/d significantly reduced the risk of relapse in high-relapse-risk patients compared with placebo, reducing the relapse rate from 71% to 55%, but was ineffective in preventing recurrence of inactive Crohn's disease following surgical resection. Mesalamine 4 g/d was effective in decreasing weaning failure due to steroid dependence by 67%, although the relapse rate was not significant compared with placebo at the end of 12 months. Following surgical resection, mesalamine was unable to significantly reduce the incidence of recurrence compared with placebo at the end of 1 year. In patients with active ulcerative colitis, oral mesalamine 2 and 4 g/d was superior to placebo in inducing remission compared with placebo. Among patients with prior steroid of sulfasalazine treatment, rectal mesalamine 4 g hs achieved a remission rate of 78% in more than 12 weeks of therapy. Other studies have not found a dose-response relationship with lower dosages of mesalamine. Whereas nicotine 15-25 mg/d administered as a transdermal patch produced greater symptomatic improvement in active ulcerative colitis compared with placebo, nicotine 15 mg/16 h produced results no different from those with placebo in maintaining remission in active colitis. Nicotine appears to have an adverse effect on the course of Crohn's disease and is not recommended.

CONCLUSIONS

Mesalamine has demonstrated clinical effectiveness as a therapeutic agent in the treatment of active ulcerative colitis and inactive Crohn's disease. Although its relationship to inflammatory bowel disease has been known for many years, the usefulness of nicotine for the treatment of active ulcerative colitis requires further exploration before it can be recommended as therapeutic agent.

Ulcerative colitis: an epithelial disease?

There is now considerable evidence that abnormalities of the structure and function of the colonic epithelium are present in patients with ulcerative colitis and that many of these may occur independently of mucosal inflammation. It is proposed that epithelial abnormalities are the central defect that underlie the development of mucosal inflammation and its chronicity. A simple model for pathogenesis is proposed in which inflammation develops only when epithelial barrier function is impaired to an extent which permits the influx of luminal pro-inflammatory molecules to the lamina propria. Several candidate hypotheses regarding the molecular basis for the abnormality are addressed. The mechanism by which the barrier function is critically impaired involves the interaction of the abnormal epithelium with luminal, mucosal and systemic factors. Focusing on the epithelium would potentially lead to a conceptually different management approach and the development of novel therapeutic strategies.

Pharmacokinetics of nicotine carbomer enemas: a new treatment modality for ulcerative colitis

BACKGROUND

Ulcerative colitis is largely a disease of nonsmokers, and transdermal nicotine is of therapeutic value in the active disease. Because side effects are common, we developed a topical enema formulation of nicotine.

OBJECTIVE

To study the pharmacokinetics of nicotine complexed with a polyacrylic carbomer and administered by enema to eight healthy volunteers and to eight patients with active ulcerative colitis, verified sigmoidoscopically.

PATIENTS AND METHODS

All 16 subjects were nonsmokers. The mean age for normal subjects was 33 years; the mean for patients with ulcerative colitis was 60 years. Median stool frequency for patients with ulcerative colitis was four daily. Patients were taking 5-amino salicylic acid compounds and five were taking oral prednisolone (median dose, 12 mg daily). Nicotine, 6 mg, complexed with carbomer 974P, 400 mg, was administered in a 100 ml enema after an overnight fast, with serial blood measurements taken over 8 hours. Serum nicotine and cotinine were measured by gas liquid chromatography. Area under the concentration-time curves were calculated by the trapezoidal method, and the terminal elimination half-life was derived by extrapolation of the log-linear terminal phase.

RESULTS

With the exception of nicotine time to reach peak concentration, which was longer in patients (median of 60 minutes compared with 45 minutes; p < 0.005), other comparisons between normal subjects and patients showed no statistically significant difference, although there was considerable inter-subject variation. Maximum concentration of nicotine, 8.1 +/- 3.5 ng/ml, in the 16 subjects occurred after a median of 60 minutes (range, 30 to 180 minutes); maximum cotinine concentrations of 60.4 +/- 11.5 ng/ml occurred after 4 hours. Side effects in five subjects were mild (four subjects) or moderate (one subject) and included lightheadedness, nausea, and headache; these five subjects were female lifelong nonsmokers of low body weight.

CONCLUSION

Because most of the active ingredient of nicotine is converted to continine on the first pass through the liver, substantial concentrations can be achieved at the site of disease with only modest rises in serum nicotine, which are responsible for side effects; cotinine has low pharmacologic activity. Topical administration of nicotine may be useful treatment for distal ulcerative colitis.

The role of cigarettes and nicotine in the onset and treatment of ulcerative colitis

Epidemiological evidence suggests that ulcerative colitis is a disease of nonsmokers, while Crohn's disease is a disease of smokers. The relative risk of developing ulcerative colitis is not only greater in nonsmokers, in addition there appears to be a rebound effect in smokers who quit, with the heaviest (ex-)smokers increasing their relative risk of the disease the most. This factor poses an ethical dilemma for health professionals giving advice on stopping smoking, which may thus have a serious detrimental effect on the health of some patients. Nicotine is believed to be the pharmacological ingredient of tobacco that is responsible for this beneficial effect and several clinical trials using nicotine have demonstrated it to be an effective therapeutic agent in the treatment of ulcerative colitis. Although the aetiology of ulcerative colitis is unclear, current research using nicotine-based products has produced some interesting clues, together with the possibility of some form of therapeutic treatment based on nicotine administration.

Pilot trial of nicotine patches as an alternative to corticosteroids in ulcerative colitis

In ten patients with mild to moderate clinical relapses of ulcerative colitis during treatment with mesalazine (1 g t.i.d.) and with a previous history of poorly tolerated steroid courses, transdermal nicotine (15 mg daily) was added for 4 weeks. Clinical findings were assessed by employing Rachmilewitz's activity index. In 7 of the patients, clinical remission was achieved, the results persisting for up to 3 months after nicotine withdrawal. Endoscopic and histological examination, when performed, confirmed the clinical findings. Nicotine patches may represent a good alternative to steroids in selected patients with mild to moderate relapses of ulcerative colitis. The precise mechanism of action remains unknown.

Epidemiology of inflammatory bowel disease: an update

What have epidemiologic studies on IBD taught so far? Consistent findings are as follows: A high incidence of both CD and UC in industrialized countries and an increase in these areas of the incidence of CD during the years 1960-80 followed by a plateau phase, and a more stable pattern in UC during the same period have been found. A greater number of mild cases have probably been diagnosed recently. This also helps to explain the differences in severity and survival between community and referral centre groups. The male to female ratio is greater than 1 in UC, and this is the opposite in CD. Mortality of IBD has decreased during the past decades. As young people are especially prone to develop IBD, most of those affected will have their disease for many years. In developing IBD, genetic influences are of importance. However, epidemiologic studies strongly point to possible interactions between genetically determined features and environmental or other factors. Of these exogenic factors smoking is the most consistent, being of negative influence in CD and protective in UC. Diet and oral contraceptives may influence disease expression, and perinatal events such as viral infections may alter adult susceptibility. The question remains open whether UC and CD are one diseases entity. Similarities in the epidemiologic features of UC and CD support the idea of IBD being one disease. Other findings suggest dividing UC and CD into further subgroups: in CD it has been suggested that fibrostenotic, penetrating, and inflammatory behaviour should be considered different disease entities; in UC some groups consider ulcerative proctitis a disease entity on its own, separating it from the proximally extending colitis. In therapeutic trials this approach has proved to be of importance, and it is not inconceivable that in subgroups, with regard to aetiopathogenetic mechanisms, different factors have to be looked for.

A controlled double blind study of azathioprine in the management of Crohn's disease

While immunosuppressive agents are used widely in the management of Crohn's disease, their efficacy has not been well established in randomised controlled trials. This study was designed to examine whether azathioprine increases remission rate when used in conjunction with a diminishing dose regimen of prednisolone over a period of 12 weeks. It further examined whether azathioprine offers any therapeutic advantage over placebo in the maintenance of remission in Crohn's disease over a period of 15 months. Sixty three patients with active Crohn's disease were treated with a 12 weeks diminishing dose of prednisolone and at the same time entered into a randomised, double blind 15 month trial of either azathioprine (2.5 mg/kg) or placebo. Remission rates between the two groups were compared at 12 weeks and at 15 months. There was no significant difference in the proportion of patients who had achieved and maintained remission by week 12 but at 15 months there was a highly significant difference in the proportion of patients in remission (42% receiving azathioprine v 7% receiving placebo), p = 0.001. Using life tables this beneficial effect was reflected as the difference in the median number of days on the trial (p = 0.02). There were significantly greater decreases over the trial period in the median erythrocyte sedimentation rate, C reactive protein, and leucocyte count in the azathioprine group. There were no cases of severe bone marrow suppression or clinical pancreatitis. In conclusion, azathioprine offers a therapeutic advantage over placebo in the maintenance of remission in Crohn's disease.

Ulcerative colitis responsive to smoking and to nicotine chewing gum in a patient with alpha 1 anti-trypsin deficiency

Ulcerative colitis is one of the few diseases in which smoking appears to confer some benefit (1). We report a patient whose ulcerative colitis deteriorated on several occasions on stopping cigarettes, and improved on restarting smoking. As a result, she continued smoking despite developing airflow limitation and severe emphysema. She was subsequently found to have alpha 1 anti-trypsin deficiency. She later noticed that she could get a similar benefit in her colitis with nicotine chewing gum as she had with cigarettes. For patients with smoking-responsive ulcerative colitis, non-tobacco forms of nicotine delivery such as gum or transdermal patches should be considered to avoid the hazards of cigarette smoke.