Gender-related and city- and countryside-related differences in patients with ulcerative colitis in a Chinese population

Protective effect of appendectomy against the onset of ulcerative colitis: A case-control study

BACKGROUND

Previous studies suggest that appendectomy has a protective effect against ulcerative colitis (UC); however, relatively few studies focusing on this topic have been reported in China.

AIM

To explore the correlation between appendectomy and the onset of UC.

METHODS

A total of 313 patients with newly diagnosed UC and 313 healthy individuals were selected for this study. According to whether their appendix was removed before the diagnosis of UC, patients were divided into appendectomized and non-appendectomized groups. Their general clinical data, appendectomy history, disease severity, extent of involvement, and blood routine test results were collected to evaluate the relationship between appendectomy and the onset of UC.

RESULTS

The study revealed that the average time interval for the diagnosis of UC after appendectomy was 14.72 ± 13.87 years. 55.81% patients were diagnosed with UC five years after appendectomy. Among them, eight patients underwent appendectomy before the age of 20 years and were diagnosed with UC five years later. In the appendectomized group, the onset age of UC was higher, and the degree of disease activity was significantly lower. This group had a higher proportion of patients in clinical remission or with mild disease and a lower proportion of patients with severe disease. The extent of lesions in the appendectomized group was limited, with a higher proportion of E1 and E2, whereas a lower proportion of E3 lesions.

CONCLUSION

Appendectomy may delay the onset of UC, reduce disease severity, and lessen the scope of involvement.

Association between short-term exposure to fine particulate pollution and outpatient visits for ulcerative colitis in Beijing, China: A time-series study

Environmental factors play an important role in the development of ulcerative colitis (UC). However, only few studies have examined the effects of air pollution on UC occurrence. We conducted a time-series analysis to explore the association between short-term exposure to fine particulate matter (PM_2.5) and outpatient visits for UC in Beijing, China. In total, 84,000 outpatient visits for UC were retrieved from the Beijing Medical Claim Data for Employees between January 1, 2010 and June 30, 2012. Measurements of daily PM_2.5 concentrations were obtained from the United States Embassy air-monitoring station. A generalized additive model with quasi-Poisson link was applied to examine the association between PM_2.5 concentrations and outpatient visits for UC stratified by sex, age, and season. We found that short-term exposure to PM_2.5 was significantly associated with increased daily outpatient visits for UC at lag 0 day. A 10 μg/m³ increase in PM_2.5 concentration at lag 0 day corresponded to a 0.32% increase in outpatient visits for UC (95% confidence interval (CI), 0.05-0.58%; P = 0.019). There was a clear concentration-response association between daily outpatient visits for UC and PM_2.5 concentrations. The PM_2.5 effects were significant across all sex and season subgroups, without evidence of effect modification by sex (P = 0.942) or season (P = 0.399). The association was positive in patients younger than 65 years old but negative in those 65 years old or older, although the difference was not significant (P = 0.883). In conclusion, our study demonstrated that short-term exposure to ambient PM_2.5 was significantly associated with an increased risk of daily outpatient visits for UC, especially in younger people. Additional studies are warranted to confirm our findings.

Multicenter case-control study of the risk factors for ulcerative colitis in China

AIM

To evaluate potential risk factors in the development of ulcerative colitis (UC) in China.

METHODS

A total of 1308 patients with UC and 1308 age-matched and sex-matched controls were prospectively studied in China. The UC cases were collected from 17 hospitals in China from April 2007 to April 2010. Uniform questionnaires were designed to investigate risk factors including smoking, appendectomy, stress, socio-economic conditions, nonsteroidal anti-inflammatory drugs (NSAIDs), oral contraceptives, diet, breastfeeding, infections and family sanitary conditions. Group comparisons by each factor were done using simple logistic regression analysis. Conditional logistic regression was used for multivariate analysis.

RESULTS

By univariate analysis, the variables predictive of UC included feeling stress, light and heavy alcoholic drinking, spicy food, sugar consumption and infectious diarrhea, while heavy tea intake and tap water consumption were protective against UC. On multivariate analysis, the protective factor for UC was tap water consumption [odds ratios (OR) = 0.424, 95%CI: 0.302-0.594, P < 0.001]; while the potential risk factors for UC were heavy sugar consumption (OR = 1.632, 95%CI: 1.156-2.305, P < 0.001), spicy food (light intake: OR = 3.329, 95%CI: 2.282-4.857, P < 0.001; heavy intake: OR = 3.979, 95%CI: 2.700-5.863, P < 0.001), and often feeling stress (OR = 1.981, 95%CI: 1.447-2.711, P < 0.001). Other factors, such as smoking habit, appendectomy, breastfeeding, a history of measles, rural or urban residence, education, oral contraceptives, and NSAID use have not been found to have a significant association with the development of UC in the present study.

CONCLUSION

Our study showed tap water consumption was a protective factor for UC, while spicy food, heavy sugar consumption and often feeling stress were risk factors for UC in this Chinese population.

The role of gender and organ specific autoimmunity

Autoimmunity is influenced by multiple factors including gender and sex hormones. A definite female predominance is found in many autoimmune diseases. Gender is also associated with differences in clinical presentation, onset, progression and outcome of autoimmune diseases. Sex hormones might influence the target organ's vulnerability to an autoimmune response. Gender differences also exist in organ specific autoimmune diseases such as multiple sclerosis, Guillain-Barré syndrome, Crohn's disease and celiac disease. Nevertheless, other organ specific autoimmune diseases (i.e. ulcerative colitis) are seemingly characterized with similar prevalence in both males and females. The reason for gender differences in certain autoimmune diseases remains unknown, but may be attributed to sex hormone influence, fetal microchimerism, X chromosome inactivation, and X chromosome abnormalities. Sex hormones have been found to have immune modulating properties, as well as providing cellular protection following tissue damage in certain circumstances. Sex hormones also influence innate and adaptive immune cells, number of B and T cells, antigen presentation and cytokine secretion. Herein, we review the influence of gender on organ-specific autoimmune diseases affecting the heart, blood vessels, central nervous system and gastrointestinal tract. It appears that sex hormones may have a therapeutic potential in several autoimmune conditions, although further research is required before therapeutic recommendations can be made.