Inflammatory bowel disease (IBD), including ulcerative colitis (UC), and Crohn disease generally first afflict patients as young adults and persist as chronic conditions throughout their lifetimes. In Asia (excluding Australia and New Zealand), IBD is relatively uncommon, although UC is more prevalent than Crohn disease. However, recent literature has shown that IBD is increasing in incidence in many parts of the Asia Pacific region.1 Using UC as an example, its incidence in Japan was reported to be five in 100,000 individuals in 1974, increasing to 20 per 100,000 in 1991.2 In South Korea, Yang and colleagues3 reported a significant 23-fold increase (0.07–1.68 per 100,000) in UC between 1986 and 2005. In Hong Kong, the mean annual age-specific incidence of UC has increased six-fold from 1986 to 2006 (from 0.3 to 1.8 per 100,000).4 A westernized environment and lifestyle are considered to be primary causative factors of the upward increment of IBS frequency in Asia.1 Preliminary observations also indicate that IBD patients in Asia seem to have less familial clustering, milder disease manifestation, lower rates of surgery, and lower rates of UC-related colorectal cancer compared with the West.1
In Taiwan, research into the cause, prevention, or management of IBD is extremely rare. In an abstract based on data from the Taiwan National Health Insurance Research Database, the annual incidence rates of UC progressively increased from 0.54 in 1998 to 0.94 in 2008 per 100,000, and the UC prevalence rates significantly increased from 0.72 in 1998 to 7.05 in 2008 per 100,000.5 Using the similar database, Lin and colleagues6 demonstrated that Taiwanese women with UC were at a higher risk of having preterm and low birth weight babies compared with mothers unaffected by the disease. Nevertheless, whether the clinical presentation and health histories of UC patients in Taiwan share similar or have different clinical features with other Asian or Western countries remains unclear.
In this issue, Wei and colleagues7 have presented a comprehensive review summarizing the clinical data from a large series of UC patients (n = 406) diagnosed at the National Taiwan University Hospital from 1988 to 2008. This study may be one of the largest Chinese patient series to be reported in the English-language medical literature. The authors found that the number of UC patients gradually increased in their hospital during the investigating period. These patients usually presented with bloody stool (77.3%) or with total colonic involvement (41.0%). Also, UC in Taiwan occurs slightly more frequently in men than women (1.35:1), and it has the peak age of occurrence at around 36 years. Overall, these findings were similar to those results obtained from studies in other Asian countries.8,9
IBD can result from both genetic influences and environmental factors. In this study, the authors found 1.5% of their patients had a family history of UC, similar to family history prevalence in Korea (1.8%), and much lower than that prevalences in Western countries (5%–8%).10 This finding could partly arise from the lower general IBD incidence/prevalence in Asia countries than in Western countries. Despite these numbers, the result of our study still suggests that family clustering of IBD cases, although less common, is still observed in Asian populations.
Regarding disease control and progression the current study confirmed the belief that most UC patients in Asia, including Taiwan, have a milder form UC, which can usually be controlled with 5-aminosalicylic acid alone (72.4%). Nevertheless, the authors demonstrated that some UC patients in Taiwan were still steroid-dependent (4%), while others might even need immunosuppressive agents or surgery (5.5%) to control the disease activity or UC-related complications. Dysplasia and colorectal cancer (CRC) are recognized as the long-term complications of UC. In a meta-analysis generated from data of Western countries, the CRC rates are 1.6% at 10 years, 8.3% at 20 years, and 18.4% at 30 years.1 In Asia, the prevalence of CRC in UC patients in the Asia-Pacific region appears to be much lower, ranging from 0.3%–1.8%.9 In the current series, six UC patients (1.5%, primarily female) developed CRC at least 10 years after UC diagnosis, which seemed to be at the higher range of the Asian data and almost comparable with the occurrence rates of dysplasia/CRC in UC from Western countries. This unusual observation deserves for further investigation. With the potential increasing numbers of UC cases in Taiwan, colonoscopic surveillance with biopsy may be warranted for every UC patients after 8 years of diagnosis. Extraintestinal manifestations (4.5%) can also be observed in UC patients in Taiwan, with primary sclerosing cholangitis most commonly observed (n = 6; 1.5%). This finding is consistent with the proposition that UC-associated PSC is less prevalent in the Asia-Pacific region (0%–2.2%) when compared to the West (2%–7%).9
The current study results presented by Wei and colleagues7 are valuable in showing us the burgeoning trend and frequency of UC in Taiwan. Through the study, we obtain an overview of the current clinical status and natural history of UC in Taiwan. UC is not hard to diagnose, and conventional therapy is usually adequate for managing the disease activity for the UC patients in Taiwan. Nevertheless, various unanswered questions and challenges in the pathogenesis, diagnosis and management of UC in Taiwan or even Asia still remain. For example, what is the exact cause for the increased incidence and prevalence of IBD in Taiwan/Asia? Is there any genetic marker characterized the IBD patients in Taiwan/Asia? Is there any change in the intestinal microbiota pattern among the IBD patients in Taiwan/Asia? What is the optimal surveillance protocol for the IBD patients in Taiwan/Asia? What is the optimal dose of steroid or immunosuppressive agents for UC patients in Taiwan/Asia? What is the better time to switch to biologic agents or even colectomy in Taiwan/Asia? Therefore, it is hoped that researchers in this area would undertake further studies in this rapid evolving field, where such efforts can ultimately lead to enhanced care for the management of our potentially rising UC patients.
Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan, ROC
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