ABSTRACT
Background and Aim
The epidemiological patterns of inflammatory bowel disease (IBD) can give insights into disease etiology and health system burden. This study aimed to measure the population‐based prevalence in Canterbury and consider the region's position within the 4‐stage epidemiological model of IBD.
Methods
Gastroenterology clinics in Canterbury were searched for patients with a confirmed diagnosis of IBD. Demographic and disease details (including Montreal phenotype) were extracted from individual medical records. The prevalence of IBD, Crohn's disease (CD), ulcerative colitis (UC) and inflammatory bowel disease unclassified (IBDU) was established for the total population and for age, sex, and ethnic sub‐groups.
Results
Altogether 4042 individuals (1 in 150 people) in Canterbury with IBD were identified. The point prevalence of IBD on 1st January 2024 was 671 (95% CI 651–692) per 100 000 persons. The prevalence of CD 386 (95% CI 370–402) was higher than UC 264 (95% CI 251–277) each per 100 000. Almost three times as many individuals had IBD in 2024, compared to a 2005 study. The majority of the cohort were New Zealand European (92.9%) followed by Māori (4.2%), Asian (2.6%) and Pacific peoples (0.3%). Older adults (65+ years) comprised 21% of the population with a prevalence of 845 (95% CI 789–904) per 100 000 persons.
Conclusion
Canterbury has the highest reported prevalence of IBD in Oceania to date, and there is a growing proportion of older age patients. The rapid rise in cases supports the hypothesis that Canterbury is in the compounding prevalence stage of the epidemiological model of IBD.
Keywords: Crohn's disease, epidemiology, inflammatory bowel disease, New Zealand, ulcerative colitis
1. Introduction
Inflammatory bowel diseases (IBD) are chronic, immune‐mediated gastrointestinal conditions [1]. Each of the diseases (Crohn's disease (CD), ulcerative colitis (UC) and inflammatory bowel disease unclassified (IBDU)), impact patient's quality of life and burden health systems. The magnitude of this burden can be estimated by the disease prevalence.
A four‐stage epidemiological model of IBD predicts that Western countries will move through a period of increasing incidence as the disease is ‘unmasked’, to one where incidence stabilizes and prevalence continues to rise [2]. This is because IBD is typically diagnosed at a young age and is a chronic disease that has relatively low mortality [2]. This model provides a framework to compare IBD across countries and consider what the future disease burden may look like in different areas.
New Zealand does not have a patient registry for IBD, nor are there administrative databases that record all interactions of people with IBD with the health system. Without these data sources, prevalence studies require direct case note review. However, the strength of this approach is that more in‐depth patient‐level data can be collected. Furthermore, population‐based research gathers information on all patients within a defined geographic area, enabling the inclusion of less severe disease presentations. A recent systematic review found four prevalence studies from New Zealand with a pooled IBD prevalence rate of 310 per 100,000 persons [3]. This pooled rate is similar to the first population‐based IBD prevalence study from Canterbury, which found a prevalence of 308 per 100,000 persons in 2005 [4]. In contrast, the highest prevalence rate seen to date in Oceania came from a 2019 Australian administrative general practice‐based study, which reported a prevalence rate of 653 per 100,000 persons [5].
This study aimed to measure the point prevalence of IBD, CD, UC, and IBDU in Canterbury as of 1 January 2024. Further aims were to describe the characteristics of the patients currently living with IBD in Canterbury, to compare with prior data collected two decades earlier in 2005, and to consider Canterbury's position within the IBD epidemiological model.
2. Methods
2.1. Study Design
A population‐based methodology was used to include all patients living with IBD in the Canterbury area on 1 January 2024.
2.2. Study Location
Canterbury is a region on the east coast of the South Island, which includes New Zealand's second‐largest city: Christchurch. In 2023 the Canterbury District Health Board (CDHB) geographic area had an estimated resident population of 602 000 people with a median age of 38.3 years [6]. New Zealand European was the predominant ethnicity (70%) with lower proportions of Māori (16%), Pacific (8%) and Asian (15%) peoples [6].
2.3. Case Definition
Individuals with IBD were defined as having a diagnosis of CD, UC, or IBDU established by a gastroenterologist. Standard diagnostic criteria for IBD include a combination of clinical, endoscopic, radiologic, and laboratory evidence, and these were used to exclude differential causes and diagnose IBD [7]. Patients diagnosed with IBD outside the Canterbury region were included if they moved to Canterbury and were treated by a local gastroenterologist.
2.4. Case Identification
New Zealand has a universal public health system for tertiary‐level care. In Canterbury this is provided by Christchurch Public Hospital, which treats both adults and children. Private specialist care is also available. All the private gastroenterology providers in Canterbury work part‐time and also work concurrently at Christchurch Public Hospital. The electronic medical records of all patients attending gastroenterology outpatient appointments at Christchurch Public Hospital were screened to identify possible patients with IBD. Colonoscopy and endoscopy reports were searched for the keywords Crohn's, CD, ulcerative colitis, UC, inflammatory bowel disease, IBD, proctitis, pancolitis, and colitis.
Gastroenterologists and IBD nurses working in Canterbury were introduced to this research and asked to provide details of patients who may be included in this study. Lists of patients who had ever taken a biologic medication used to treat IBD were checked for possible inclusion, as were previous IBD research studies from the Christchurch Gastroenterology department [4, 8, 9].
All private gastroenterology practices in Canterbury were approached to participate in this prevalence study. Upon agreement, their clinical records were searched (using the same IBD keywords listed above) for possible patients with IBD.
2.5. Quality Check
To check the quality of the case identification, independent searches of the endoscopy and histology databases from Christchurch Public Hospital were performed after the outpatient data entry. The IBD keywords listed above were used to search histology records from 2005 (when the last IBD prevalence study was performed [4]) up to 1 January 2024.
2.6. Data Collection
The medical records of all patients with possible IBD were reviewed by trained medical research assistants. After confirming the patient had a diagnosis of IBD that met the standard diagnostic criteria, details of the disease type, diagnosis date, and demographic characteristics of the patients were gathered. The Montreal phenotype [10] of each patient was also determined at diagnosis (where possible) and a worst‐ever phenotype at the entry point to the study was established.
2.7. Data Management
Demographic and disease information for each of the individuals with IBD was entered into Crohn's Colitis Care (CCCare): a secure patient management system used at Christchurch Public Hospital [11].
2.8. Data Analysis
Data was reported as frequency counts, means, and proportions, and prevalence was estimated with 95% confidence intervals. Age‐standardized prevalence was calculated using the World Health Organization (WHO) world standard population [12]. X 2 and independent t‐tests were used to compare the current results with those from previous studies using a p < 0.05 level of statistical significance.
2.9. Ethics
This research was approved by the University of Otago Human Research Ethics Committee: reference number HD23/098.
3. Results
3.1. Prevalence
On 1 January 2024, there were 4042 individuals with IBD in Canterbury (1 in 150 people). CD was more common, comprising 58%, compared to 39% with UC (Table 1). There were slightly more females (n = 2108, 52%) than males (n = 1933, 48%). IBD was most often diagnosed when patients were in their 30s, with CD being diagnosed, on average, at a younger age than UC (32.3 versus 37.3 years, p < 0.001). The current average age of the IBD population was 48.7 years (SD 17.7), and the mean disease duration of the cohort was 13.8 years (SD 11.4).
TABLE 1.
Inflammatory bowel disease in Canterbury on 1 January 2024: frequency counts and summary statistics.
| IBD | % | CD | % | UC | % | IBDU | % | Total population | % | |
|---|---|---|---|---|---|---|---|---|---|---|
| N | 4042 | 100 | 2323 | 57.5 | 1587 | 39.3 | 132 | 3.3 | 602 000 | |
| Male | 1933 | 47.8 | 1092 | 47.0 | 771 | 48.6 | 70 | 53.0 | 300 900 | 50.0 |
| Female | 2108 | 52.2 | 1231 | 53.0 | 815 | 51.4 | 62 | 47.0 | 301 100 | 50.0 |
| Mean age (years) (SD) | 48.7 | 17.7 | 46.1 | 17.4 | 52.4 | 17.4 | 48.6 | 19.5 | 38.3 | |
| Mean age at diagnosis (years) (SD) | 34.4 | 16.0 | 32.3 | 15.9 | 37.3 | 15.4 | 36.6 | 17.8 | NA | |
| Māori | 171 | 4.2 | 109 | 4.7 | 55 | 3.5 | 7 | 5.3 | 61 900 | 10.3 |
| Pacific | 14 | 0.3 | 10 | 0.4 | 3 | 0.2 | 1 | 0.8 | 19 300 | 3.2 |
| Asian | 104 | 2.6 | 53 | 2.3 | 49 | 3.1 | 2 | 1.5 | 89 600 | 14.9 |
| European (and other) | 3753 | 92.9 | 2151 | 92.6 | 1480 | 93.3 | 122 | 92.4 | 432 500 | 71.8 |
Abbreviations: CD, Crohn's disease, IBDU, inflammatory bowel disease unclassified; UC, ulcerative colitis.
The point prevalence of IBD was 671 per 100 000 people (Table 2). The prevalence of IBD rose with age to a peak of approximately 50 years, and then fell with age (Figure S1).
TABLE 2.
Prevalence of inflammatory bowel disease in Canterbury on 1 January 2024, and for selected ethnic groups.
| IBD | (95% CI) | CD | 95% CI | UC | 95% CI | IBDU | 95% CI | |
|---|---|---|---|---|---|---|---|---|
| Prevalence per 100 000 | 671 | (651–692) | 386 | (370–402) | 264 | (251–277) | 21.9 | (18.4–25.9) |
| Male prevalence per 100 000 | 642 | (614–672) | 363 | (342–385) | 256 | (239–275) | 23.3 | (18.3–29.2) |
| Female prevalence per 100 000 | 700 | (671–731) | 409 | (387–432) | 271 | (253–290) | 20.6 | (15.9–26.2) |
| Māori prevalence per 100 000 | 276 | (237–320) | 176 | (145–212) | 88.8 | (67.6–114.8) | 11.3 | (4.9–22.4) |
| Pacific prevalence per 100 000 | 72.5 | (41.3–118.8) | 51.8 | (26.3–92.4) | 15.5 | (4.0–42.3) | 5.2 | (0.3–25.6) |
| Asian prevalence per 100 000 | 116 | (95.3–140.1) | 59.2 | (44.8–76.8) | 54.7 | (40.9–71.7) | 2.2 | (0.4–7.4) |
| European and other prevalence per 100 000 | 868 | (840–896) | 497 | (477–519) | 342 | (325–360) | 28.2 | (23.5–33.6) |
Abbreviations: CD, Crohn's disease; CI, confidence interval; IBDU, inflammatory bowel disease unclassified; UC, ulcerative colitis.
3.2. Ethnicity
New Zealand Europeans comprised over 90% of Canterbury patients with IBD (Table S1). Māori and European ethnic groups had higher proportions of CD than UC (p < 0.001). A very small number of individuals of Pacific Island ethnicity had IBD. The proportions of Māori, Asian, and Pacific peoples with IBD were less than those in the general Canterbury population (p < 0.001) and the proportion of New Zealand Europeans was higher in the IBD cohort (Table S1).
3.3. IBD In Children and Adolescents
There were 155 children aged 2–19 years with IBD in Canterbury, with an average age at diagnosis of 12.1 years (SD 4.1). Most (77.4%) children had CD, with 18.1% having UC and 4.5% IBDU. The prevalence of IBD for 0–19 year‐olds was 109.9 (95% CI 93.6–128.3) per 100 000 children (Table S1). In the 10–14 year age group, IBD was more common in females, but this pattern reversed in the 15–19 year old group.
3.4. Older Adults With IBD
Older adults aged 65 years and above made up 21% of the IBD population with an age‐specific prevalence of 845 (95% CI 789–904) per 100 000 persons. CD was more prevalent than UC in older females, but UC was more common than CD in older males (Table S2). Those currently over 65 were on average 52.7 years old (SD 15.6) when they were diagnosed. Sixty‐nine (1.7%) of the IBD population were aged 85 years or over in 2024, with an IBD prevalence of 601 (95% CI 471–756) per 100 000 persons.
3.5. Age and Sex Distribution of IBD
The highest prevalence rates occurred for people aged 50 to 60 years with the age‐specific IBD prevalence exceeding 1000 per 100 000 persons (Figure 1). CD was more common than UC up to 70 years of age, after which UC became predominant (Figure S1). From 60 years of age, the male prevalence of IBD exceeded the female prevalence, driven primarily by higher rates of UC in older males (Figure S2).
FIGURE 1.
Age‐specific prevalence for IBD: (A), CD: (B), UC: (C), by sex in Canterbury on 1 January 2024, compared to the age‐specific prevalence in Canterbury on 1 June 2005.
The age‐standardized prevalence was IBD 574.9 per 100 000, CD 344.2 per 100 000, UC 212.1 per 100 000, and IBDU 18.6 per 100 000 persons. These are lower than the crude prevalence rates reflecting the higher proportion of older people in the Canterbury population.
3.6. Disease Characteristics
Although inflammatory disease (68%) was the most common CD behavior, many patients in Canterbury experienced stricturing (18%) or penetrating (14%) complications (Table 3). Extensive UC (E3) and ileocolonic CD (L3) were the most common disease locations at 36% and 42%, respectively. Penetrating CD behavior (B3) was less common (9.3%) in older adults (65 years and over) than in the overall cohort (14%).
TABLE 3.
Montreal phenotype classification of the Canterbury IBD prevalent population at 1 January 2024 and 1 June 2005.
| Montreal classification Crohn's disease | 2024, N (%) | 2005, N (%) | p |
|---|---|---|---|
| Age at diagnosis | |||
| A1 ≤ 16 years | 331 (14.2) | 77 (10.8) | |
| A2 17–40 years | 1368 (58.9) | 426 (59.6) | |
| A3 > 40 years | 624 (26.9) | 212 (29.7) | p = 0.04 |
| Location | |||
| L1 terminal ileal | 624 (26.9) | 214 (29.9) | |
| L2 colonic | 708 (30.5) | 296 (41.4) | |
| L3 ileocolonic | 984 (42.4) | 171 (23.9) | |
| L4 upper GI | 47 (2.0) | 34 (4.8) | p < 0.001 |
| Behavior | |||
| B1 non stricturing, non penetrating | 1578 (67.8) | 381 (53.3) | |
| B2 stricturing | 408 (17.6) | 185 (25.9) | |
| B3 penetrating | 335 (14.4) | 149 (20.8) | |
| P perianal | 494 (21.3) | 190 (26.6) | P < 0.001 |
| Montreal classification ulcerative colitis | |||
| Age at diagnosis, year | |||
| A1 ≤ 16 | 82 (5.2) | 38 (5.7) | |
| A2 17–40 | 906 (57.1) | 367 (54.9) | |
| A3 > 40 | 599 (37.7) | 263 (39.4) | p = 0.62 |
| Extent | |||
| E1 ulcerative proctitis | 489 (30.8) | 250 (37.4) | |
| E2 left‐sided UC (distal UC) | 529 (33.3) | 166 (24.9) | |
| E3 extensive UC (pancolitis) | 566 (35.7) | 252 (37.7) | p < 0.001 |
Note: 2005 data from Gearry et al. [4].
3.7. Temporal Patterns From 2005 to 2024
A population‐based prevalence study of IBD conducted in the same geographical area in 2005 identified a prevalence rate of 308 per 100 000 persons [4]. The prevalence rate in the present study is 2.8 times higher than the 2005 rate (Table 4, Figure 1). The proportion of patients with CD has increased between the two studies (50% in 2005 and 57%) in 2024). The mean age of patients in the 2005 study was 47.4 years, and the 2024 mean age was 48.7 years. On average, patients had been diagnosed with IBD for 11.1 years in 2005 compared to 13.8 years in 2024 (p < 0.001) (Figure S3).
TABLE 4.
Comparison of IBD prevalence study results from Canterbury in 2005 and 2024.
| 1 June 2005 | 1 January 2024 | Ratio | |
|---|---|---|---|
| N | 1420 | 4042 | 1:2.8 |
| IBD rate per 100 000 | 308 (95% CI 292–324) | 671 (95% CI 651–692) | 1:2.2 |
| CD (%) | 715 (50%) | 2323 (57%) | 1:3.2 |
| CD rate per 100 000 | 155 (95% CI 144–167) | 386 (95% CI 370–402) | 1:2.5 |
| UC (%) | 668 (47%) | 1587 (39%) | 1:2.4 |
| UC rate per 100 000 | 145 (95% CI 134–156) | 264 (95% CI 251–277) | 1:1.8 |
Note: 2005 data from Gearry et al. [4].
4. Discussion
High prevalences of IBD: 671 (95% CI 651–692), CD: 386 (95% CI 370–402) and UC: 264 (95% CI 251–277) each per 100 000 persons, were seen in this population‐based study. The prevalence of IBD in Canterbury is the highest reported in Oceania to date; with a recent systematic review [3] identifying an Australian study as having the previous highest prevalence of 653 (95% CI 623–684) per 100 000 persons [5]. Interestingly, this 2019 Australian study found a higher prevalence of UC (334 per 100 000 persons) and a lower prevalence of CD (306 per 100 000 persons) than the current study.
Australia and New Zealand are geographically, demographically, and economically similar, so this congruence in the prevalence of IBD may reflect both genetic and lifestyle similarities between the populations. There were methodological differences between the Australian study, which used an administrative database of general practice (GP) records, and the current study, which used a population‐based medical records review. Research using administrative databases may be cost‐efficient, but it relies on accurate disease coding and can suffer from misclassification bias [13]. In contrast, a medical record review approach is more resource‐intensive and therefore is often limited to a specific region, but is more accurate in confirming a diagnosis and can add clinical details such as Montreal phenotype [14].
Higher prevalences of IBD have been reported in some Northern Hemisphere studies [15](Table S3). In particular, a study conducted in the Faroe Islands reported a prevalence of IBD of 1,414 per 100,000 persons in 2021 [16]. This small, geographically isolated Danish territory had a prevalence of CD less than that seen in Canterbury (248 per 100 000 persons) but a much higher UC prevalence (934 per 100 000 persons) [16]. Genetic and environmental risk factors for IBD and, in particular, UC, in this population have been considered, including Westernization, dietary transition, smoking, and Vitamin D deficiency [16]. Faroese who migrate to Denmark gradually reduce their raised risk of UC over one to two generations to the level of the general Danish population [17]. That noted, the rates of IBD in the Danish population are also high, with a 2017 study reporting an IBD prevalence of 893 per 100,000 persons [18]. The percentage prevalence of IBD in Denmark has nearly doubled from 0.45% in 2002 to 0.89% in 2017 [18]. In contrast, the prevalence of IBD in Canterbury has more than doubled from 0.31% in 2005 to 0.67% in 2024. Environmentally, New Zealand and the Faroe Islands are both small island nations with latitudes far from the equator, but the majority of the Canterbury population lives in urban centres, so are more likely to have lifestyles more similar to the Danish mainland population.
Another area reporting a high prevalence of IBD is Lothian, Scotland where in 2018 the IBD prevalence was 784 per 100 000 persons [19]. Like the changes noted in Canterbury, Lothian reported a doubling of IBD prevalence from 0.4% in 2003 to 0.8% in 2018 [19]. The Scottish study highlighted a high proportion of older adults with IBD in the prevalent population. This was also a key finding from the current study and similarly seen in reports from Australia [20] and Canada [21]. Older patients with IBD have more comorbidities, may have different treatment patterns (including less biologic use due to the perceived risk of complications of immunosuppression), and require more surgery and hospitalization [22, 23, 24]. Despite this, the overall excess mortality for patients with IBD is small and in some studies not higher than that seen in the general population [25, 26, 27]. This combination of increasing numbers of older patients living with IBD and low rates of mortality is a contributor to the increasing rates of prevalence observed in Western industrialized countries [28].
The 4‐stage epidemiological model of IBD predicts that the incidence and prevalence of IBD evolve as a country develops economically, IBD is unmasked, and environmental and lifestyle factors that come with development influence the rates of the disease [2]. Most Western countries are presumed to be in Stage 3: Compounding Prevalence, where the incidence of IBD has stabilized but the prevalence continues to rise. The current data show a high prevalence of IBD and a significant increase from the previous study in the same area in 2005 [4] underscoring the growth in the number of people living with IBD: the prevalence rates have more than doubled in the 18 years between the studies. The change in the shape of the prevalence curves for IBD (Figure 1A) illustrates this, with the 2005 data showing crests at 30, 60, and 80 years which have smoothed out in the 2024 data to show a more symmetrical curve with a new peak prevalence at approximately 50 years. This prevalence rise, along with IBD incidence rates which have fallen from their 2014 high of 39.5 per 100 000 [8], supports the hypothesis that Canterbury is currently experiencing compounding prevalence of IBD. Further information on the migration and mortality of patients with IBD would be useful to determine the reductions in prevalence between 2005 and 2024, but unfortunately, data on these topics were not collected in this study. Other Western countries have forecast that prevalence could reach in excess of 1000 per 100 000 persons (i.e., > 1%) over the next decade [14].
The increasing number of patients living with IBD has implications for the health system with direct costs of medications, hospitalization, and surgery to treat and diagnose IBD rising with the number of patients. In addition, there are indirect costs of IBD incurred by patients, caregivers, and society including the loss of productivity due to the disease [29]. CD has been associated with higher health costs than UC [30] and one of the characteristics of the Canterbury IBD cohort was an excess of CD compared to studies from Scandinavia and Western Europe where UC dominated.
People of New Zealand European ethnicity were the predominant ethnic group in 2024 (92.9%), with lower proportions of Māori (4.2%) and Pacific peoples (0.3%). In the equivalent 2005 study, 99% of the cohort were European or other, 1% Māori, and no Pacific Islanders with IBD were identified [4]. Although the prevalence of Māori and Pacific peoples with IBD is still low in 2024, the rates have increased since 2005 (Māori prevalence in 2024 was 276 per 100 000 persons, and 41.6 per 100 000 persons in 2005 p < 0.001, Pacific prevalence in 2024 was 72.5 per 100 000 persons and 0 in 2005 p = 0.01). A Canadian study also noted an increasing prevalence of IBD in Indigenous First Nations Canadians from 1999 to 2017 [31]. The 4‐stage epidemiological model of IBD describes the rise in the diagnosis of IBD as a function of both increased access to health care and the Westernization of lifestyles [2]. In New Zealand, Māori and Pacific Peoples are significantly more likely to miss endoscopy appointments as compared to New Zealand Europeans [32], and this disparity in access will have flow‐on effects as a colonoscopy is almost always needed for an IBD diagnosis. Health inequalities between the different ethnic groups within the Canterbury population may position them at a different stage within the IBD epidemiological model. An increasing incidence of IBD in Māori was recently observed over 5 years in a North Island region of New Zealand [33]. Similarly, in Canterbury, the incidence of IBD in Māori and Pacific peoples may still be increasing (Stage Two‐Acceleration in Incidence) whereas incidence has appeared to have stabilized in the larger New Zealand European ethnic group (Stage Three—Compounding Prevalence) [2].
The prevalence of IBD observed in older adults was high and is expected to increase in the next decade as incident cases are diagnosed [34] and the existing IBD population ages. This has implications for health care provision as older patients with IBD can be more complex with age‐related comorbidities and polypharmacy challenges.
Another segment of the Canterbury population experiencing IBD growth is children. Although rare in very young children, IBD rapidly becomes more prevalent in children over 10 years of age. IBD diagnosed in childhood presents a lifelong burden to both the patient and the health system. The prevalence of IBD in children and adolescents (0–19 years) observed in this study (109.9 per 100 000 children) was higher than any other area reported in a recent systematic review of pediatric IBD in Oceania [35].
4.1. Limitations
Despite attempts to capture all patients with IBD in Canterbury, some individuals may not have been included in this study. As the data collection approach focused on secondary care gastroenterology clinics, individuals with mild or quiescent disease managed only in primary care may not be included. Another limitation of the study relates to the way ethnicity information was collected and recorded in medical records; this data may have not been verified by the patients and a ‘self‐report’ approach may have yielded more accurate ethnicity data.
In summary, this population‐based study has shown a very high prevalence of IBD in Canterbury on 1 January 2024. The number of people living with IBD has more than doubled in this area since 2005, supporting the hypothesis that Canterbury is experiencing compounding prevalence.
Conflicts of Interest
The authors declare no conflicts of interest.
Supporting information
Table S1. Prevalence of IBD in children and adolescents aged ≤ 19 years on 1 January 2024 in Canterbury.
Table S2. Prevalence of IBD in older adults aged 65 years and older in Canterbury on 1 January 2024.
Table S3. Comparison of the prevalence per 100 people of IBD, CD and UC in selected contemporary studies.
Figure S1. Age‐specific prevalence of IBD, CD and UC in Canterbury 1 January 2024.
Figure S2. Age‐sex‐specific prevalence rates for IBD, CD and UC in Canterbury 1 January 2024.
Figure S3. Year of diagnosis by disease type for patients with IBD in Canterbury 1 January 2024 (diagnosed from 1970 to 2023).
Acknowledgments
The authors would like to thank Dr. Millie de Vries, Dr. Nina McVicar, and the data entry team for their work on this project; the Christchurch Hospital Gastroenterology department; Gastroenterology and Endoscopy Specialists; and Christchurch Surgical Associates. Open access publishing facilitated by University of Otago, as part of the Wiley ‐ University of Otago agreement via the Council of Australian University Librarians.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Table S1. Prevalence of IBD in children and adolescents aged ≤ 19 years on 1 January 2024 in Canterbury.
Table S2. Prevalence of IBD in older adults aged 65 years and older in Canterbury on 1 January 2024.
Table S3. Comparison of the prevalence per 100 people of IBD, CD and UC in selected contemporary studies.
Figure S1. Age‐specific prevalence of IBD, CD and UC in Canterbury 1 January 2024.
Figure S2. Age‐sex‐specific prevalence rates for IBD, CD and UC in Canterbury 1 January 2024.
Figure S3. Year of diagnosis by disease type for patients with IBD in Canterbury 1 January 2024 (diagnosed from 1970 to 2023).