Researchers from The Chinese University of Hong Kong (CUHK) have conducted the world’s first systematic review of the global incidence and prevalence of Inflammatory Bowel Diseases (IBD) in the 21st century.

A continuous surge in the non-western world was observed in the study, with the incidence in Hong Kong having risen about 30 times in the past 30 years, much more seriously than in other Asia regions, such as Japan, Taiwan and Singapore.


CUHK’s researchers regard this increase as alarming and describe the surge of IBD cases a public health challenge worldwide.

Incidence of IBD has been rapidly rising in Asia

IBD was traditionally regarded as a disease of Westernised nations. Over 1.5 million and 2 million people suffer from the disease in North America and Europe respectively. As a result, a heavy burden is imposed on the local healthcare systems.

To provide insights into the epidemiology of IBD in the 21st century from a global perspective, Prof Joseph Sung, Vice-Chancellor and President of CUHK; Prof Francis Chan, Dean of the Faculty of Medicine; and Prof Siew Chien Ng, Professor of the Department of Medicine and Therapeutics, together with gastroenterologists and epidemiologists from the University of Calgary in Canada evaluated more than 11,000 studies on IBD, published from 1990 to 2016. Among them, 147 studies were identified for full-text review.

Prof Siew Ng (left) states that Inflammatory Bowel Disease was traditionally regarded as a disease of Westernised nations, but newer epidemiologic studies indicate that the incidence is rising in Asia, highlighting that IBD has emerged as a global public health challenge. Photo credit: CUHK
Prof Siew Ng (left) states that Inflammatory Bowel Disease was traditionally regarded as a disease of Westernised nations, but newer epidemiologic studies indicate that the incidence is rising in Asia, highlighting that IBD has emerged as a global public health challenge. Photo credit: CUHK

In the study, the highest reported prevalence values were in Europe (ulcerative colitis 505 per 100 000 in Norway; Crohn's disease 322 per 100 000 in Germany) and North America (ulcerative colitis 286 per 100 000 in the USA; Crohn's disease 319 per 100 000 in Canada). The prevalence of inflammatory bowel disease exceeded 0.3% in North America, Oceania, and many countries in Europe. Nevertheless, although prevalence remains high, the overall trend reported stable or even decreasing incidence of inflammatory bowel disease in North America and Europe.

On the other hand, newer epidemiologic studies indicate that the incidence and prevalence are rising in newly industrialised countries in Asia, South America, Eastern Europe and Africa.

Results showed that there is a paradigm shift in the epidemiology of IBD in the 21st century. Since 1990, the incidence of IBD has stabilized in the Western world while other regions are showing a rising incidence as they have undergone Westernization, in terms of living style. In Hong Kong, there were 26 new IBD cases in a million people, which are higher than the figures in some other parts of Asia.



‘The increase in incidence of IBD in regions other than the Western world is alarming. Taking Hong Kong as an example, the figure has increased about 30 times in the past three decades. Since the actual causes of IBD remain unknown and there is no cure at present, we believe the golden time to identify the cause or to prevent the disease is in the coming 10 years, before the incidence has peaked,’ says Ng.

‘The high prevalence of IBD in the Western world will challenge clinicians to provide high quality and cost-efficient care to patients with IBD. More striking is the observation that as newly industrialised countries have transitioned towards a Westernized society, IBD emerges and its incidence rises rapidly. Consequently, we will need to prepare our clinical infrastructure and personnel to manage this complex and costly disease,’ adds Dr Gilaad Kaplan, Associate Professor, Cumming School of Medicine at the University of Calgary.

Cross-boundary and local research to identify risk factors of IBD

Yet, the continual surge also provides unique opportunities to identify the cause of IBD.

Miss Sum was diagnosed with Crohn’s disease in 2016, a subtype of Inflammatory Bowel Diseases (IBD). She wishes studies of the gastroenterology team of the Faculty of Medicine at CUHK could figure out the cause of the disease and relieve IBD patients from the suffering. Photo credit: CUHK
Miss Sum was diagnosed with Crohn’s disease in 2016, a subtype of Inflammatory Bowel Diseases (IBD). She wishes studies of the gastroenterology team of the Faculty of Medicine at CUHK could figure out the cause of the disease and relieve IBD patients from the suffering. Photo credit: CUHK

Apart from this comprehensive and updated systematic review conducted with the University of Calgary, CUHK has just announced that Ng’s team is also collaborating with research centres in Australia and mainland China on a research project entitled ‘The ENIGMA Studies - Eastern Inflammatory Bowel Disease (IBD) Gut Microbiota’ (ENIGMA). This project aims to study the association between IBD, especially Crohn's disease, and the patients’ gut microbiota and dietary habits.

The team is also studying mothers and infants with IBD in order to identify bacterial transmission pattern that may potentially lead to preventive measures for the disease.

Results of the systematic review have just been published in the leading medical journal The Lancet. MIMS

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