Elsevier

The Lancet

Volume 390, Issue 10114, 23 December 2017–5 January 2018, Pages 2769-2778
The Lancet

Articles
Worldwide incidence and prevalence of inflammatory bowel disease in the 21st century: a systematic review of population-based studies

https://doi.org/10.1016/S0140-6736(17)32448-0Get rights and content

Summary

Background

Inflammatory bowel disease is a global disease in the 21st century. We aimed to assess the changing incidence and prevalence of inflammatory bowel disease around the world.

Methods

We searched MEDLINE and Embase up to and including Dec 31, 2016, to identify observational, population-based studies reporting the incidence or prevalence of Crohn's disease or ulcerative colitis from 1990 or later. A study was regarded as population-based if it involved all residents within a specific area and the patients were representative of that area. To be included in the systematic review, ulcerative colitis and Crohn's disease needed to be reported separately. Studies that did not report original data and studies that reported only the incidence or prevalence of paediatric-onset inflammatory bowel disease (diagnosis at age <16 years) were excluded. We created choropleth maps for the incidence (119 studies) and prevalence (69 studies) of Crohn's disease and ulcerative colitis. We used temporal trend analyses to report changes as an annual percentage change (APC) with 95% CI.

Findings

We identified 147 studies that were eligible for final inclusion in the systematic review, including 119 studies of incidence and 69 studies of prevalence. 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. Overall, 16 (72·7%) of 22 studies on Crohn's disease and 15 (83·3%) of 18 studies on ulcerative colitis reported stable or decreasing incidence of inflammatory bowel disease in North America and Europe. Since 1990, incidence has been rising in newly industrialised countries in Africa, Asia, and South America, including Brazil (APC for Crohn's disease +11·1% [95% CI 4·8–17·8] and APC for ulcerative colitis +14·9% [10·4–19·6]) and Taiwan (APC for Crohn's disease +4·0% [1·0–7·1] and APC for ulcerative colitis +4·8% [1·8–8·0]).

Interpretation

At the turn of the 21st century, inflammatory bowel disease has become a global disease with accelerating incidence in newly industrialised countries whose societies have become more westernised. Although incidence is stabilising in western countries, burden remains high as prevalence surpasses 0·3%. These data highlight the need for research into prevention of inflammatory bowel disease and innovations in health-care systems to manage this complex and costly disease.

Funding

None.

Introduction

The inflammatory bowel diseases, Crohn's disease and ulcerative colitis, are chronic idiopathic disorders causing inflammation of the gastro-intestinal tract.1 In the past decade, inflammatory bowel disease has emerged as a public health challenge worldwide.2 In North America and Europe, over 1·5 million and 2 million people suffer from the disease, respectively.3 Outside the western world (ie, countries influenced by a western European cultural heritage, including the USA, Canada, Australia, New Zealand, and all countries in western Europe), the number of individuals affected by inflammatory bowel disease remains unclear.4

Traditionally regarded as a disease of westernised nations, the epidemiology of inflammatory bowel disease is changing throughout the world at the turn of the 21st century.4 Although the incidence of ulcerative colitis and Crohn's disease increased in the western world in the latter half of the 20th century,4, 5 little was known about the changing incidence in other parts of the world. Now, newer epidemiological studies suggest that incidence might be rising rapidly in South America, eastern Europe, Asia, and Africa. Additionally, an increase in disease incidence among ethnicities and nationalities in whom inflammatory bowel diseases were previously uncommon has substantial implications for the understanding of pathogenesis and environmental triggers in differing populations.6 This epidemiological shift, which is being seen in newly industrialised countries and in Asian immigrants to the west, mirrors the experience reported in the west more than 50 years ago, occurring with rapid socioeconomic development.7

Research in context

Evidence before this study

In a previous systematic review, we searched MEDLINE from 1950 to 2010 (8103 citations) and Embase from 1980 to 2010 (4975 citations) for population-based studies that reported the incidence or prevalence of Crohn's disease or ulcerative colitis. The search identified 260 population-based studies on the incidence or prevalence of Crohn's disease or ulcerative colitis. Collectively, these studies defined the epidemiological patterns of the inflammatory bowel diseases during the 20th century. Since the 1950s, the incidence and prevalence of inflammatory bowel disease steadily increased in the countries of North America, Europe, and Australia. During this time, more than two-thirds of studies reported that incidence rates were increasing significantly in the western world. We define the western world as consisting of countries influenced by a western European cultural heritage, including the USA, Canada, Australia, New Zealand, and all countries in western Europe. By contrast, few population-based studies on the epidemiology of inflammatory bowel disease were published from countries in Africa, Asia, and South America. At the turn of the 21st century, additional epidemiological studies have been reported from across the world. For example, the Asia-Pacific Crohn's and Colitis Epidemiologic Study Group (ACCESS) defined the incidence of inflammatory bowel disease in 12 countries in Asia and Australia. These newer studies, which were not included in the original systematic review, have shed light on the changing global epidemiological patterns of inflammatory bowel disease.

Added value of this study

We did a systematic review of population-based studies on the incidence (119 studies) or prevalence (69 studies) of inflammatory bowel disease from 1990 to 2016. Since 1990, incidence rates have shifted in western countries, with 73% of studies on Crohn's disease and 83% of studies on ulcerative colitis showing stable or falling incidence. However, disease burden remains high, with prevalence surpassing 0·3% in North America, Oceania, and most countries in Europe. By contrast, newly industrialised countries in Africa, Asia, and South America whose societies become increasingly westernised and urbanised, are mirroring the progression of inflammatory bowel disease in the western world during the 1900s.

Implications of all the available evidence

Since the recognition of ulcerative colitis in 1875 and Crohn's disease in 1932, the incidence of inflammatory bowel disease has increased substantially in the western world. Our findings show a paradigm shift whereby the incidence of inflammatory bowel disease in most western countries has begun to stabilise and in some regions decrease. However, after several decades of sharply rising incidence, the prevalence of inflammatory bowel disease has risen to more than 0·3% of the population in North America, Australia, and many countries in Europe. The high prevalence of inflammatory bowel disease in the western world will challenge clinicians and health policy makers to provide quality and cost-efficient care to patients with inflammatory bowel disease. More striking is the observation that as newly industrialised countries have transitioned towards a westernised society, inflammatory bowel disease emerges and its incidence rises rapidly. The peak in the incidence of inflammatory bowel disease has probably not yet transpired in these newly industrialised countries. Consequently, these countries will need to prepare their clinical infrastructure and personnel to manage this complex and costly disease. During the past 100 years, the incidence of inflammatory bowel disease has risen, then plateaued in the western world, whereas countries outside the western world seem to be in the first stage of this sequence. Thus, future research should focus on identification of the environmental risk factors seen during the early stages of industrialisation of society to highlight avenues to prevent the development of inflammatory bowel disease.

In the western world, inflammatory bowel disease is associated with morbidity, mortality, and substantial costs to the health-care system.3, 8 The rising incidence of inflammatory bowel disease in newly industrialised countries could indicate an emerging epidemic of the disease outside the western world. This observation suggests that the impact of inflammatory bowel disease on health-care systems will need to be reassessed in the context of shifting epidemiological patterns throughout the world. Furthermore, insight into geographical patterns and disease time trends will help researchers and policy makers to prepare the clinical infrastructure and health-care resources needed to mitigate the burden of inflammatory bowel disease.

We did a systematic review of population-based studies reporting the incidence of inflammatory bowel disease across the world since 1990 based on different geographical regions and did temporal trend analyses of incidence. We aimed to update the information provided by our previous report,5 and provide insight into the epidemiology of inflammatory bowel disease from a global perspective.

Section snippets

MethodsSearch strategy and selection criteria

For this systematic review, we first identified studies reporting the incidence and prevalence of inflammatory bowel disease from 1990 onwards from our previous systematic review.5 We updated the previous database search by searching MEDLINE and Embase from Dec 1, 2010, to Dec 31, 2016, to identify population-based studies reporting the incidence and prevalence of inflammatory bowel disease. We did the search using a pre-determined search strategy and in accordance with the quality of reporting

Results

We identified 95 records that fulfilled our criteria from our previously published systematic review.5 For the period from Dec 1, 2010, to Dec 31, 2016, our search identified an additional 11 170 records; 3514 from MEDLINE and 7656 from Embase. After removal of duplications and initial screening, 226 articles were eligible for full-text review (figure 1). The observed agreement between reviewers for eligibility of articles on the initial screening was 99·5%. On full-text review of 226 articles,

Discussion

During the 20th century, inflammatory bowel disease was mainly a disease of westernised countries of North America, Europe, and Oceania.5 At the turn of the 21st century, inflammatory bowel disease became a global disease with accelerating incidence in the newly industrialised countries of Asia, South America, and Africa, where societies have become more westernised.2, 4 Estimated prevalence continues to rise in North America, in many countries in Europe, and in Australia and New Zealand, which

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