Dissecting the rising tide of inflammatory bowel disease among youth in a changing world: insights from GBD 2021

Abstract

Objectives

This study investigates the alarming epidemiological trends of inflammatory bowel disease (IBD) among children and young adults, highlighting the associated disease burden on global health.

Materials and methods

Utilizing data from the Global Burden of Disease (GBD) study 2021, we conducted a comprehensive analysis of age-standardized incidence rates (ASIR), age-standardized mortality rates (ASMR), disability-adjusted life years (DALYs), and estimated annual percentage changes (EAPC). Future trends were forecasted using the Bayesian age-period-cohort model.

Results

From 1990 to 2021, IBD incidence and DALY rates remained persistently high, with a concerning upward trend noted among children and young adults. While men experienced a decline in DALY rates, women faced increasing burdens. In 2021, high-income regions, particularly North America, reported the highest incidence and DALY rates, contrasting sharply with Central Latin America, which exhibited the lowest ASIR. Southeast Asia presented the most favorable DALY rates. A notable negative correlation was identified between DALY rates and socio-demographic index (SDI) at the national level, with high and high-middle SDI countries continuing to bear a substantial burden, while low and middle SDI nations faced rising challenges.

Conclusions

The persistent high burden of IBD in children and young adults signifies a critical public health concern. The marked geographical and gender disparities underscore the urgent need for tailored regional and population-based strategies aimed at primary prevention and effective management. This study illuminates the pressing necessity for policy interventions to address the growing epidemic of IBD among vulnerable populations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00384-025-04821-0.

Introduction

Inflammatory bowel disease (IBD) encompasses a group of chronic gastrointestinal inflammatory disorders, including ulcerative colitis (UC) and Crohn’s disease (CD). These diseases are non-communicable and incurable, affecting millions worldwide [1]. Traditionally, IBD viewed as a Western affliction, while the incidence of IBD in Western countries plateaued between the late twentieth and early twenty-first centuries, emerging industrialized nations in Asia and Latin America have witnessed a rapid increase in cases [2]. For instance, data from the Asia–Pacific Crohn’s Disease and Colitis Epidemiological Study (ACCESS) revealed significant regional disparities in China, with incidence rates ranging from 0.54 per 100,000 in Xi’an to 3.64 per 100,000 in Guangzhou [3]. Preliminary data suggest that the incidence of IBD in newly industrialized countries may approach Western levels within the next decade, with some regions in Brazil, China, and India reporting incidence rates in the same range as those observed in the West [3, 4]. In a study, it is expected that by 2035, the prevalence rate in Iran will increase by 2.5 times, reaching 69,000 cases, while the prevalence rate in North Africa and the Middle East will increase by 2.3 times, reaching 220,000 cases, which is four times the prevalence rate in India (2.2 million cases). The prevalence rate in East Asia will increase by 1.5 times (4.5 million cases). The prevalence rates in high-income Asia–Pacific and Southeast Asia will be 1.6 times and 183 cases and 199,000 cases higher, respectively [5]. Furthermore, as observed in emerging industrialized countries, the global incidence of IBD in children has also increased [6]. The variability in reported incidence underscores the escalating burden of IBD, influenced by socio-economic development and lifestyle changes. This necessitates a comparative analysis of disease burden across different countries and regions, enabling better healthcare resource allocation and planning.

IBD can manifest at any age, but it is most prevalent among adolescents and young adults [7]. Given that there is currently no definitive cure for IBD, available pharmacological treatments primarily focus on alleviating inflammation and maintaining remission [8]. The direct healthcare costs for patients with IBD are three times that of non-IBD patients and have been on the rise over the years [9]. Additionally, IBD is associated with indirect societal costs, which can be more hidden and widespread [10]. The impact of IBD on quality of life and healthcare costs highlights the importance of epidemiological studies, particularly among adolescents (ages 15–39), to mitigate the economic strain associated with non-communicable diseases [11].

The Global Burden of Disease (GBD) study [12], managed by the Institute for Health Metrics and Evaluation, assesses IBD across 204 countries and regions, enabling the identification of regional differences in disease burden, particularly among adolescents. Therefore, our aim is to evaluate trends in IBD among the adolescent population using GBD data. This will involve analyzing key metrics such as age-standardized incidence rates (ASIR), age-standardized mortality rates (ASMR), age-standardized disability-adjusted life years (DALYs), and estimated annual percentage change (EAPC) to delineate the distribution and trends of IBD globally, regionally, and nationally, with projections extending through 2040.

Methods

Data source

Data on the burden of inflammatory bowel disease (IBD) across 204 countries and territories were sourced from the Global Burden of Disease (GBD) study. This comprehensive dataset was derived from various resources, including census data, household surveys, civil registration, vital statistics, disease registries, health service utilization records, air pollution surveillance, satellite imaging, and disease notifications. In GBD 2021, IBD was classified using the 10th revision of the International Classification of Diseases (ICD-10) codes: K50–K51.319, K51.5–K52, K52.8–K52.9. The data were standardized by sex, age, and year, providing insights into prevalence, morbidity, mortality, years of life lost, years of healthy life lost due to disability, and disability-adjusted life years (DALYs). Further details regarding data acquisition and processing methodologies can be found in previous studies [12–14].

This study focused on the burden of IBD among individuals aged 15–39 years. This age group experiences the highest incidence of IBD [15], particularly pronounced in emerging industrialized regions [3]. Current global guidelines for IBD lack specific screening, prevention, and treatment recommendations for this demographic [16], potentially leading to delayed diagnosis and management. Thus, we analyzed IBD data from 1990 to 2021 for the 15–39 age group, categorized by country, region, and sex.

Statistical analysis

We calculated age-standardized rates (ASRs) for DALYs, mortality, and morbidity, along with their associated 95% confidence intervals (CIs), using the GBD 2021 standard population. The ASR was computed using the formula:

$$\text{ASR}=\frac{{\sum }_{i=1}^A{n_{\text{i}}a}_{\text{i}}}{{\sum }_{i=1}^A{n}_{\text{i}}}\times 100000$$

where the relationship between a_i, n_i and i_th age groups has been elucidated in previous studies [12, 17]. We employed the estimated annual percentage change (EAPC) and its 95% CI to quantify trends in age-standardized incidence rates from 1990 to 2021 using linear regression:

y = α + βx + ε, and EAPC = 100 × (e^β − 1). This formula is used to represent trends in age-standardized indicators [17]. Additionally, we categorized 204 countries and regions into five sociodemographic index (SDI) categories: low SDI, medium SDI, and high SDI, based on the geometric means of total fertility, per capita income, and mean years of education for individuals aged 15 years or older [12]. A higher SDI indicates greater developmental status, as detailed in prior GBD studies [18]. To analyze trends in IBD-related disease burden over time, we utilized a Joinpoint regression model [19]. We assessed mean annual percent changes (APCs) with their respective 95% CIs to evaluate trends in incidence, prevalence, and mortality.

APC

This refers to the rate of change within each segment when the data exhibits different trends or turning points at various time periods. Joinpoint divides the data into multiple segments at these turning points, and the APC is reported separately for each segment. For instance, if the analysis detects a significant trend change (such as a sharp increase or decrease) in a specific year, that year is considered a “Inflection point,” and the corresponding APC for that segment is calculated.

AAPC

In contrast, when we aim to calculate the average rate of change across the entire study period, Joinpoint reports the AAPC, which reflects the overall annual average trend of change, rather than segmenting the trends. APC provides the annual rate of change for each segment, making it suitable for situations where multiple trend-turning points exist within the data. AAPC, on the other hand, is a weighted average of the trends across the entire period, offering an overall view of the annual change [20]. The analysis was conducted using “Joinpoint” software from the National Cancer Institute’s Surveillance Research Program.

We also applied a Bayesian age-period-cohort model, a log-linear Poisson model, to estimate predictions, assuming a multiplicative influence of age, period, and cohort [21]. For predictions based on the GBD 2021 data, we used an annual increase of 1% as a negative reference and an annual decrease of 1% as an optimistic reference. All statistical analyses and visualizations were performed using R statistical software (v. 4.3.2), with a significance threshold set at p < 0.05.

Results

Incidence, mortality, and DALYs of IBD in children and young adults

In 2021, the global incidence of inflammatory bowel disease (IBD) among individuals aged 15–39 years reached 123,343 cases, a substantial increase from 84,960 cases in 1990. In contrast, this upward trend was less pronounced in Western countries; for instance, in the USA, cases increased from 17,814 in 1990 to 19,680 in 2021, while in the UK, the number rose from 3015 to 3734 during the same period. Notably, newly industrialized countries, such as India, experienced a more significant rise, with cases increasing from 12,489 in 1990 to 28,275 in 2021 (Fig. 1B, Table 1).

Fig. 1.

Analysis of incidence rate of inflammatory bowel disease in children and adolescents per 100,000 population in 210 countries and regions. A 2021 age standardization rate. B The number of cases in 2021. C Estimated annual percentage change from 1990 to 2021. Abbreviation: IBD, inflammatory bowel disease; ASIR, age standardized incidence rate; EAPC, estimated annual percentage change

Table 1.

Incident cases and age-standardized incidence of IBD in children and young adults (age 15–39) in 1990 and 2021, and its temporal trends from 1990 to 2021

Location	Num_1990	ASR_1990	Num_2021	ASR_2021	EAPC_CI
Afghanistan	66.5 (52.3–85)	2.1 (1.7–2.7)	338 (264.4–439.9)	2.8 (2.2–3.6)	0.8 (0.63–0.98)
Albania	85.1 (66.9–107.8)	6 (4.7–7.6)	73.7 (58.1–95.3)	7.8 (6.1–10.1)	0.85 (0.81–0.89)
Algeria	300.2 (231.2–390.4)	3 (2.3–3.9)	751.4 (579.2–1008.4)	4.4 (3.4–5.9)	1.22 (1.17–1.26)
American Samoa	0.2 (0.1–0.2)	0.8 (0.6–1)	0.2 (0.1–0.2)	0.9 (0.7–1.2)	0.37 (0.3–0.43)
Andorra	3.7 (2.9–4.8)	15 (11.7–19)	4.2 (3.3–5.4)	16.4 (13–21.2)	0.21 (0.12–0.3)
Angola	51 (39.4–66.9)	1.3 (1–1.7)	192.3 (149.2–250.6)	1.6 (1.2–2.1)	0.75 (0.7–0.81)
Antigua and Barbuda	0.7 (0.5–0.9)	2.6 (2.1–3.3)	1.1 (0.8–1.4)	3.2 (2.5–4.2)	0.51 (0.42–0.59)
Argentina	588.8 (453.2–781.4)	4.8 (3.7–6.4)	916.1 (706.1–1192.4)	5.2 (4–6.8)	0.27 (0.22–0.31)
Armenia	55.4 (43.3–70.8)	3.9 (3–4.9)	54.1 (41.9–72.1)	5 (3.9–6.7)	0.86 (0.69–1.03)
Australia	1370.5 (1087.5–1773.7)	20.2 (16.1–26.2)	2000.7 (1591.1–2505)	23.1 (18.4–28.9)	1.06 (0.59–1.52)
Austria	375.1 (292.2–473)	12.5 (9.7–15.8)	385.1 (308.1–484.1)	13.6 (10.9–17.2)	0.13 (0.05–0.21)
Azerbaijan	132.2 (103.1–171.6)	4.2 (3.2–5.4)	214 (165–283.2)	5.1 (3.9–6.7)	0.42 (0.3–0.54)
Bahamas	3.3 (2.6–4.2)	2.8 (2.2–3.6)	5.7 (4.4–7.4)	3.7 (2.9–4.8)	0.64 (0.54–0.74)
Bahrain	7 (5.6–8.8)	2.7 (2.2–3.4)	21.6 (16.7–27.8)	3.1 (2.4–3.9)	0.89 (0.71–1.06)
Bangladesh	1769.5 (1383.1–2282.1)	4.2 (3.3–5.4)	3650.7 (2893–4811.2)	5.3 (4.2–7)	0.62 (0.55–0.69)
Barbados	3.4 (2.8–4.1)	3.1 (2.5–3.8)	3.5 (2.7–4.6)	3.5 (2.7–4.6)	0.32 (0.12–0.53)
Belarus	132.8 (103.5–170.4)	3.4 (2.6–4.3)	134.3 (102.1–176.2)	4.6 (3.5–6)	0.99 (0.88–1.11)
Belgium	358 (303.5–428)	9.6 (8.2–11.5)	429.5 (337.6–550.4)	12.3 (9.6–15.7)	0.73 (0.61–0.84)
Belize	1.7 (1.3–2.2)	2.3 (1.8–3)	5.8 (4.6–7.6)	3.1 (2.4–4)	0.74 (0.67–0.8)
Benin	20.6 (16–26.8)	1.2 (0.9–1.6)	64.8 (50.3–85.8)	1.2 (1–1.6)	–0.12 (− 0.19 to 0.04)
Bermuda	0.8 (0.6–1)	3 (2.3–3.9)	0.6 (0.5–0.8)	3.5 (2.7–4.5)	0.46 (0.39–0.52)
Bhutan	10.3 (7.9–13.4)	3.8 (2.9–5)	19.8 (15.3–25.8)	5.7 (4.4–7.4)	1.32 (1.29–1.36)
Bolivia (Plurinational State of)	30.8 (23.5–40.4)	1.3 (1–1.6)	73.5 (55.5–99)	1.5 (1.1–2)	0.64 (0.59–0.69)
Bosnia and Herzegovina	105.9 (82.8–138)	5.6 (4.4–7.3)	71.1 (54.9–93.3)	7.1 (5.5–9.3)	0.96 (0.78–1.14)
Botswana	7.3 (5.6–9.6)	1.4 (1.1–1.9)	21.3 (16.6–27.9)	2 (1.6–2.6)	1.2 (1.12–1.27)
Brazil	1026.6 (797–1349.4)	1.6 (1.3–2.2)	2159.2 (1661.9–2908.2)	2.5 (1.9–3.4)	1 (0.38–1.62)
Brunei Darussalam	1.3 (1–1.7)	1 (0.8–1.3)	2.3 (1.8–3.1)	1.1 (0.9–1.5)	0.29 (0.26–0.32)
Bulgaria	200.7 (157.7–254.9)	6.7 (5.3–8.6)	171.2 (134.4–215.8)	9 (7.1–11.4)	1 (0.95–1.05)
Burkina Faso	36.2 (28–47.2)	1.1 (0.9–1.5)	100.9 (78.5–130.7)	1.2 (0.9–1.5)	0.06 (0.01–0.1)
Burundi	24.9 (19.2–32.5)	1.2 (0.9–1.6)	70.7 (54.4–94.2)	1.3 (1–1.8)	0.42 (0.3–0.54)
Cabo Verde	1.4 (1.1–1.8)	1.1 (0.8–1.4)	3.6 (2.8–4.7)	1.4 (1.1–1.9)	0.71 (0.57–0.84)
Cambodia	22.3 (16.8–29.3)	0.6 (0.4–0.8)	55.6 (42.6–74.4)	0.8 (0.6–1)	0.86 (0.79–0.94)
Cameroon	47.7 (37.3–62.7)	1.3 (1–1.6)	189.2 (145.7–242.5)	1.5 (1.1–1.9)	0.35 (0.23–0.46)
Canada	4352.6 (3996.7–4740.1)	39.2 (36–42.6)	4027.9 (3262.4–4930)	34 (27.5–41.6)	–0.79 (− 1.17 to 0.4)
Central African Republic	13.5 (10.4–17.6)	1.3 (1–1.7)	30.5 (23.8–40.3)	1.4 (1.1–1.8)	0.23 (0.22–0.24)
Chad	22.9 (17.7–29.3)	1.1 (0.8–1.4)	68.3 (53.3–87.6)	1.1 (0.8–1.4)	–0.13 (− 0.21 to 0.05)
Chile	247.3 (191.1–320.8)	4.3 (3.3–5.6)	359.5 (277.6–487.3)	5.1 (3.9–6.9)	0.44 (0.35–0.53)
China	4007.1 (3082.7–5320.8)	0.7 (0.6–1)	7196.8 (5512.2–9717.6)	1.6 (1.2–2.1)	3.34 (2.65–4.03)
Colombia	150.8 (113.2–198.2)	1.1 (0.8–1.4)	242 (184.9–317.8)	1.2 (0.9–1.6)	0.35 (0.06–0.65)
Comoros	2.1 (1.6–2.7)	1.2 (0.9–1.5)	4.9 (3.8–6.4)	1.6 (1.2–2.1)	0.83 (0.71–0.96)
Congo	12 (9.3–15.5)	1.3 (1–1.6)	36.6 (28.8–47.8)	1.7 (1.3–2.2)	0.99 (0.94–1.05)
Cook Islands	0.1 (0–0.1)	0.7 (0.6–1)	0.1 (0–0.1)	0.9 (0.7–1.2)	0.73 (0.64–0.81)
Costa Rica	7.8 (5.9–10.4)	0.6 (0.5–0.8)	12.1 (9.1–16.8)	0.6 (0.5–0.9)	0.09 (0.05–0.12)
Croatia	134.8 (103.8–173.6)	7.4 (5.7–9.6)	117.3 (91.7–151.3)	9.4 (7.3–12.1)	0.61 (− 0.02 to 1.24)
Cuba	123.2 (96.9–158.1)	2.5 (2–3.2)	109.4 (85–139)	3.1 (2.4–3.9)	0.36 (0.23–0.49)
Cyprus	30.3 (23.7–39.2)	9.9 (7.7–12.7)	59.9 (47.1–76.5)	11.9 (9.4–15.2)	0.5 (0.41–0.59)
Czechia	705 (565.1–872)	19 (15.2–23.5)	708.4 (560.1–898.4)	24 (19–30.4)	1.54 (1.08–1.99)
Democratic People's Republic of Korea	76.9 (58.6–101.5)	0.9 (0.7–1.2)	117.9 (89.5–155.7)	1.2 (0.9–1.5)	0.58 (0.52–0.64)
Democratic Republic of the Congo	166.1 (128–214.6)	1.2 (0.9–1.5)	536.3 (416.9–708.4)	1.5 (1.2–2)	0.81 (0.78–0.84)
Denmark	447.6 (370.2–525.9)	23.5 (19.4–27.6)	362.7 (281.7–445.4)	19.9 (15.4–24.4)	–0.88 (− 1.27 to 0.49)
Djibouti	2.1 (1.6–2.7)	1.2 (0.9–1.6)	8.4 (6.4–10.9)	1.5 (1.2–2)	0.74 (0.7–0.79)
Dominica	0.8 (0.6–1)	2.6 (2.1–3.4)	0.9 (0.7–1.1)	3.4 (2.6–4.4)	0.55 (0.38–0.73)
Dominican Republic	72.4 (56.4–93.4)	2.4 (1.8–3)	136.7 (106.7–179.6)	3 (2.3–3.9)	0.71 (0.63–0.78)
Ecuador	50.2 (37.6–66.2)	1.2 (0.9–1.6)	102.1 (76.9–132)	1.4 (1.1–1.8)	0.4 (0.35–0.45)
Egypt	854.3 (690.3–1036.2)	3.9 (3.1–4.7)	1912 (1474.8–2496.4)	4.5 (3.5–5.9)	0.76 (0.62–0.9)
El Salvador	12.3 (9.3–16.4)	0.6 (0.4–0.8)	14.5 (11–19.7)	0.6 (0.4–0.8)	–0.19 (− 0.24 to 0.13)
Equatorial Guinea	2 (1.5–2.6)	1.3 (1–1.7)	12.6 (9.7–16.1)	1.8 (1.4–2.3)	1.25 (1.06–1.44)
Eritrea	15.1 (11.5–19.3)	1.2 (0.9–1.5)	41.9 (32.6–53.9)	1.5 (1.2–1.9)	0.88 (0.84–0.93)
Estonia	18.9 (14.8–24.1)	3.3 (2.6–4.2)	18.3 (14.2–23.6)	4.6 (3.6–6)	1.15 (1.02–1.27)
Eswatini	4.2 (3.3–5.6)	1.4 (1.1–1.8)	8.9 (7–11.7)	1.7 (1.4–2.3)	0.67 (0.57–0.76)
Ethiopia	178.4 (138–234.1)	1 (0.8–1.3)	537.5 (415.2–704)	1.2 (0.9–1.5)	0.75 (0.65–0.85)
Fiji	2.3 (1.8–3.1)	0.7 (0.6–1)	3.5 (2.6–4.7)	1 (0.7–1.3)	0.89 (0.82–0.96)
Finland	412.1 (367.6–453.7)	22.7 (20.2–25)	306.8 (246.3–373.9)	18.4 (14.8–22.4)	–1.67 (− 2.12 to 1.21)
France	3387.5 (3193–3614.2)	15.4 (14.5–16.4)	2759 (2207.1–3472)	13.9 (11.1–17.5)	–0.66 (− 0.9 to 0.41)
Gabon	5.3 (4.2–6.9)	1.4 (1.1–1.8)	12.8 (10–16.8)	1.7 (1.3–2.2)	0.65 (0.62–0.69)
Gambia	4 (3.1–5.1)	1.1 (0.8–1.4)	12.8 (9.8–16.7)	1.3 (1–1.7)	0.45 (0.37–0.53)
Georgia	95 (72.3–124.5)	4.5 (3.4–5.8)	56.9 (44.7–73.3)	5 (3.9–6.5)	0.37 (0.27–0.47)
Germany	6657.8 (5270.7–8334.4)	22.4 (17.7–28.1)	6323.9 (4980.2–7976.7)	25 (19.7–31.5)	0.75 (0.36–1.15)
Ghana	70.5 (54.2–90.1)	1.2 (0.9–1.6)	204 (158–265.6)	1.4 (1.1–1.9)	0.44 (0.34–0.54)
Global	84,960.6 (68,689–104,858.2)	3.9 (3.1–4.8)	123,343.2 (96,841–158,444.4)	4.1 (3.3–5.3)	0.33 (0.19–0.48)
Greece	140 (115.5–168.4)	3.7 (3.1–4.5)	134.4 (105.6–171.2)	4.8 (3.8–6.1)	1.02 (0.47–1.57)
Greenland	7.1 (5.6–8.8)	26.8 (21.3–33.3)	6.3 (5.1–7.9)	31 (25.1–38.7)	0.25 (0.17–0.33)
Grenada	0.8 (0.7–1.1)	2.5 (2–3.3)	1.3 (1–1.7)	3.3 (2.6–4.3)	0.84 (0.79–0.9)
Guam	0.5 (0.4–0.7)	0.8 (0.6–1.1)	0.6 (0.4–0.7)	1 (0.8–1.3)	0.47 (0.39–0.55)
Guatemala	16.5 (12.4–22.4)	0.6 (0.4–0.8)	40.2 (29.9–54.5)	0.6 (0.4–0.8)	0.27 (0.2–0.34)
Guinea	24.7 (19.1–32.3)	1.2 (0.9–1.6)	63.3 (49.1–82.3)	1.2 (1–1.6)	− 0.13 (− 0.25 to 0.01)
Guinea–Bissau	4.4 (3.4–5.7)	1.2 (0.9–1.5)	10.8 (8.4–14.1)	1.3 (1–1.7)	0.11 (− 0.01 to 0.23)
Guyana	8.7 (6.7–11.3)	2.6 (2–3.3)	9.9 (7.7–13.2)	3.2 (2.5–4.2)	0.59 (0.47–0.7)
Haiti	57.6 (44.6–74.9)	2.4 (1.8–3.1)	153.9 (117.9–199.7)	2.8 (2.1–3.6)	0.58 (0.57–0.6)
Honduras	9.4 (7.1–12.7)	0.5 (0.4–0.7)	24.9 (19–34)	0.6 (0.4–0.8)	0.2 (0.13–0.27)
Hungary	577.2 (497.9–664.2)	15.6 (13.5–18)	496.1 (393.7–616.8)	18 (14.3–22.4)	0.56 (0.12–1.01)
Iceland	25 (21.6–28.2)	24.1 (20.8–27.2)	25.1 (19.9–30.7)	21 (16.6–25.7)	− 0.87 (− 1.02 to 0.71)
India	12,489.7 (9654.6–16,322.1)	3.7 (2.8–4.8)	28,275.8 (21,787.1–37,379)	4.6 (3.6–6.1)	0.99 (0.78–1.2)
Indonesia	511.9 (393.2–673.3)	0.7 (0.5–0.9)	884.1 (675.5–1172)	0.8 (0.6–1)	0.46 (0.42–0.5)
Iran (Islamic Republic of)	598.1 (456.7–801.4)	2.8 (2.1–3.7)	1036.3 (783.5–1389.9)	3 (2.3–4)	1.03 (0.68–1.37)
Iraq	150.6 (119.9–186.7)	2.1 (1.7–2.6)	551.2 (429.7–721.3)	3.2 (2.5–4.1)	1.27 (1.24–1.3)
Ireland	222.3 (174–281)	16.2 (12.7–20.5)	266.2 (209.1–332.6)	17 (13.4–21.3)	0.36 (0.29–0.44)
Israel	244.4 (194.5–312.3)	12.8 (10.2–16.3)	524.1 (412.3–671.1)	15.8 (12.4–20.2)	− 0.05 (− 0.67 to 0.57)
Italy	2246.2 (1807.1–2751.1)	10.5 (8.5–12.9)	1310.7 (1021.2–1665.8)	8.3 (6.5–10.5)	− 0.66 (− 0.84 to 0.47)
Jamaica	23.4 (18.4–30.2)	2.4 (1.9–3.1)	33.6 (26.3–43.9)	2.8 (2.2–3.7)	0.4 (0.3–0.49)
Japan	857.1 (673.6–1105.1)	1.9 (1.5–2.5)	698.6 (540.7–907.1)	2.2 (1.7–2.8)	0.02 (− 0.61 to 0.66)
Jordan	48.1 (38–58.6)	3.1 (2.5–3.8)	192.9 (152.6–249)	3.6 (2.8–4.6)	0.97 (0.82–1.13)
Kazakhstan	282.3 (218.6–364.5)	4.2 (3.2–5.4)	378.1 (293–504.2)	5.4 (4.2–7.2)	0.75 (0.58–0.91)
Kenya	88.3 (68.4–114.2)	1 (0.8–1.3)	279.2 (215.3–366.5)	1.3 (1–1.7)	0.91 (0.82–1)
Kiribati	0.2 (0.2–0.3)	0.7 (0.5–0.9)	0.4 (0.3–0.6)	0.8 (0.6–1.1)	0.52 (0.49–0.55)
Kuwait	35.9 (30.7–41.6)	4.2 (3.6–4.9)	87.5 (66.7–117.2)	4.1 (3.1–5.5)	− 0.66 (− 1.23 to 0.09)
Kyrgyzstan	70.1 (55.1–90.7)	3.9 (3.1–5)	119.9 (94.2–156.9)	4.4 (3.5–5.8)	0.29 (0.19–0.38)
Lao People’s Democratic Republic	9 (6.9–11.9)	0.6 (0.4–0.8)	24.3 (18.5–32)	0.8 (0.6–1)	0.78 (0.71–0.85)
Latvia	33 (26–43.5)	3.5 (2.7–4.6)	25.6 (19.7–34)	4.8 (3.7–6.3)	0.9 (0.78–1.02)
Lebanon	81.6 (63.6–107.1)	7.1 (5.5–9.3)	228.1 (176.1–292.1)	9.8 (7.6–12.6)	0.97 (0.87–1.07)
Lesotho	7.4 (5.8–9.6)	1.4 (1.1–1.8)	13.4 (10.4–17.2)	1.6 (1.3–2.1)	0.52 (0.42–0.61)
Liberia	11.4 (8.7–14.9)	1.2 (0.9–1.6)	28.3 (22–36.7)	1.3 (1–1.6)	− 0.09 (− 0.27 to 0.1)
Libya	24.9 (19.2–32.9)	1.5 (1.1–2)	98.1 (75.4–129.5)	3.3 (2.5–4.3)	3.01 (2.84–3.18)
Lithuania	58 (45.3–76.5)	4.2 (3.3–5.5)	47.6 (37.3–61.7)	5.9 (4.6–7.7)	1.42 (0.85–1.99)
Luxembourg	24.4 (19.2–30.8)	16.5 (13–20.9)	35.1 (27.9–44.7)	15.9 (12.6–20.3)	− 0.21 (− 0.28 to 0.14)
Madagascar	55.8 (42.9–72.7)	1.2 (0.9–1.6)	166.4 (129.4–215.8)	1.4 (1.1–1.8)	0.58 (0.52–0.65)
Malawi	45.4 (35.2–59.1)	1.2 (0.9–1.6)	120.8 (94.4–157.7)	1.5 (1.2–1.9)	0.85 (0.75–0.94)
Malaysia	51 (40.6–65.4)	0.7 (0.5–0.9)	131.3 (101.2–172.8)	0.9 (0.7–1.2)	1.62 (1.32–1.92)
Maldives	0.4 (0.3–0.6)	0.5 (0.4–0.7)	2 (1.5–2.7)	0.8 (0.6–1.1)	1.34 (1.26–1.41)
Mali	33.2 (25.8–43.5)	1.1 (0.9–1.5)	99.6 (76.2–129.6)	1.1 (0.9–1.5)	− 0.15 (− 0.22 to 0.08)
Malta	14.4 (11.1–18.8)	10.4 (8.1–13.6)	13.5 (10.5–17.6)	10.1 (7.9–13.2)	0.08 (− 0.04 to 0.2)
Marshall Islands	0.1 (0.1–0.2)	0.7 (0.5–0.9)	0.2 (0.2–0.3)	0.9 (0.7–1.2)	0.81 (0.75–0.86)
Mauritania	9.8 (7.6–12.4)	1.3 (1–1.6)	21.3 (16.7–27.9)	1.2 (1–1.6)	− 0.07 (− 0.24 to 0.1)
Mauritius	3.4 (2.6–4.5)	0.7 (0.5–0.9)	3.7 (2.9–5.1)	0.8 (0.6–1.1)	0.52 (0.48–0.55)
Mexico	74.6 (55.5–101.7)	0.2 (0.2–0.3)	100.5 (74.6–136.1)	0.2 (0.1–0.3)	0.23 (− 0.04 to 0.5)
Micronesia (Federated States of)	0.3 (0.2–0.4)	0.7 (0.5–0.9)	0.4 (0.3–0.5)	0.9 (0.7–1.1)	0.62 (0.59–0.65)
Monaco	1.5 (1.2–1.9)	16.2 (12.7–20.7)	1.5 (1.2–1.9)	15.9 (12.4–20.1)	− 0.28 (− 0.37 to 0.2)
Mongolia	32.4 (25.2–42)	3.7 (2.9–4.8)	65.7 (50.1–86.9)	5.2 (4–6.9)	1.13 (1.09–1.17)
Montenegro	17.4 (13.6–22)	6.9 (5.4–8.8)	15.6 (12.2–19.7)	7.6 (5.9–9.6)	0.46 (0.37–0.55)
Morocco	263.8 (204.6–342.8)	2.5 (2–3.3)	503.4 (392.3–652.2)	3.4 (2.7–4.4)	0.97 (0.91–1.04)
Mozambique	54.6 (42.5–70.7)	1.2 (0.9–1.5)	164.3 (127–211.8)	1.4 (1.1–1.8)	0.71 (0.64–0.78)
Myanmar	106.3 (80.9–138.5)	0.6 (0.5–0.8)	182.5 (139.2–243.9)	0.8 (0.6–1.1)	0.88 (0.84–0.91)
Namibia	7.8 (6–10)	1.4 (1.1–1.8)	17 (13.1–22.3)	1.6 (1.3–2.1)	0.44 (0.35–0.53)
Nauru	0 (0–0)	0.8 (0.6–1.1)	0 (0–0.1)	0.9 (0.7–1.3)	0.41 (0.31–0.52)
Nepal	296.8 (227.5–385.1)	4.1 (3.1–5.3)	689.7 (526.9–914.2)	5.1 (3.9–6.8)	0.79 (0.72–0.87)
Netherlands	1477.6 (1320.8–1646.1)	24.5 (21.9–27.3)	1506.2 (1221.8–1843.6)	28.5 (23.1–34.9)	0.92 (0.22–1.63)
New Zealand	299.7 (237.8–387.4)	21.7 (17.2–28)	403 (316.8–515.3)	22.4 (17.6–28.6)	0.08 (− 0.12 to 0.28)
Nicaragua	7.8 (5.9–10.5)	0.5 (0.4–0.7)	16.3 (12.2–22.3)	0.6 (0.4–0.8)	0.3 (0.2–0.39)
Niger	28.7 (22–37.3)	1 (0.8–1.3)	88.4 (68.5–112.3)	1 (0.8–1.3)	− 0.3 (− 0.38 to 0.23)
Nigeria	357.5 (275.3–466.5)	1 (0.8–1.4)	993.8 (774–1282.9)	1.1 (0.9–1.4)	0.07 (0–0.13)
Niue	0 (0–0)	0.7 (0.5–0.9)	0 (0–0)	0.9 (0.7–1.2)	0.84 (0.77–0.91)
North Macedonia	53.5 (41.8–68.3)	6.7 (5.3–8.6)	65.1 (51.3–83.8)	8.5 (6.7–11)	0.93 (0.87–0.99)
Northern Mariana Islands	0.2 (0.2–0.3)	0.9 (0.7–1.2)	0.2 (0.1–0.2)	1 (0.7–1.3)	0.11 (− 0.07 to 0.29)
Norway	279.8 (223.3–345.3)	17.5 (14–21.6)	373.4 (300.2–455.7)	21 (16.9–25.7)	0.38 (0.25–0.5)
Oman	20.6 (15.9–26.4)	2.5 (1.9–3.2)	92.7 (71.9–122.8)	4 (3.1–5.3)	1.55 (1.44–1.66)
Pakistan	1379.8 (1072.2–1775.2)	3.4 (2.6–4.4)	4410.8 (3432.9–5745.3)	4.5 (3.5–5.8)	0.85 (0.79–0.91)
Palau	0.1 (0–0.1)	0.8 (0.6–1.1)	0.1 (0–0.1)	1 (0.8–1.4)	0.55 (0.45–0.65)
Palestine	16.6 (12.9–21.4)	2.2 (1.7–2.8)	71.9 (55.4–93.6)	3.3 (2.5–4.3)	1.19 (1.13–1.26)
Panama	8.2 (6.2–11)	0.8 (0.6–1.1)	14.4 (10.8–19.7)	0.9 (0.7–1.2)	0.2 (0.15–0.24)
Papua New Guinea	10.1 (7.6–13.4)	0.6 (0.5–0.8)	31.3 (24–42.4)	0.7 (0.6–1)	0.53 (0.5–0.56)
Paraguay	26.9 (20.6–34.8)	1.7 (1.3–2.2)	51.7 (39.7–67.1)	1.7 (1.3–2.2)	0.21 (0.1–0.33)
Peru	105.2 (81.3–138.7)	1.2 (0.9–1.6)	220.7 (166.7–295)	1.5 (1.1–2)	0.81 (0.73–0.89)
Philippines	117.1 (89.2–158.9)	0.5 (0.3–0.6)	253.6 (193.2–338.7)	0.5 (0.4–0.7)	0.48 (0.43–0.53)
Poland	426.3 (330–554.9)	3 (2.3–3.8)	383.5 (296.2–507.6)	3.2 (2.4–4.2)	0.71 (0.54–0.88)
Portugal	314.9 (252.7–394.6)	8.3 (6.7–10.4)	303.8 (239.2–391.4)	10.3 (8.1–13.3)	1.02 (0.56–1.47)
Puerto Rico	38.2 (29.6–48.6)	2.7 (2.1–3.4)	33.8 (26.7–43.6)	3.3 (2.6–4.2)	0.59 (0.35–0.84)
Qatar	8.2 (6.2–10.9)	3.4 (2.6–4.6)	76.6 (59.2–100.5)	4.6 (3.6–6.1)	0.93 (0.89–0.97)
Republic of Korea	869.9 (702.5–1089.2)	4.1 (3.3–5.2)	985.2 (770.7–1246.1)	6.2 (4.8–7.8)	2.29 (1.39–3.19)
Republic of Moldova	60.4 (45.8–80.4)	3.5 (2.6–4.6)	56.6 (43.2–75.4)	4.6 (3.5–6.1)	0.9 (0.72–1.08)
Romania	162.1 (126.5–208.2)	1.9 (1.5–2.4)	132.1 (103.3–171.4)	2.5 (1.9–3.2)	1.77 (0.84–2.71)
Russian Federation	1819 (1407.8–2405.5)	3.1 (2.4–4.1)	1801.1 (1369.2–2418.7)	3.9 (2.9–5.2)	0.73 (0.57–0.9)
Rwanda	33.5 (25.9–43.4)	1.2 (0.9–1.6)	88 (68.2–115.9)	1.6 (1.2–2)	0.9 (0.75–1.06)
Saint Helena	59.6 (46.1–77.2)	1.3 (1–1.6)	159 (121.5–204.1)	1.4 (1.1–1.8)	0.23 (0.12–0.34)
Saint Kitts and Nevis	0.5 (0.4–0.6)	2.8 (2.2–3.6)	0.8 (0.6–1.1)	3.7 (2.9–4.8)	0.65 (0.55–0.76)
Saint Lucia	1.4 (1.1–1.9)	2.6 (2–3.3)	2.1 (1.6–2.8)	3.2 (2.4–4.2)	0.65 (0.6–0.69)
Saint Vincent and the Grenadines	1.2 (0.9–1.5)	2.5 (2–3.3)	1.3 (1–1.7)	3.2 (2.5–4.1)	0.69 (0.6–0.78)
Samoa	0.4 (0.3–0.6)	0.6 (0.5–0.8)	0.6 (0.5–0.8)	0.8 (0.6–1)	0.54 (0.5–0.58)
San Marino	2.5 (2–3.1)	26.3 (21.2–33.1)	2.4 (1.9–3)	26.7 (21.4–33.8)	0.17 (0.03–0.31)
Sao Tome and Principe	0.4 (0.3–0.6)	1 (0.8–1.3)	1.2 (0.9–1.5)	1.3 (1–1.7)	0.66 (0.56–0.76)
Saudi Arabia	181.2 (139.2–234.9)	2.7 (2.1–3.5)	534.6 (418.1–692.4)	2.9 (2.3–3.7)	− 0.22 (− 0.38 to 0.05)
Senegal	31 (24–40.5)	1.1 (0.9–1.5)	83.7 (64.6–109.6)	1.3 (1–1.7)	0.52 (0.37–0.68)
Serbia	246.6 (193.4–313.9)	6.9 (5.4–8.7)	251 (195–329)	8.5 (6.6–11.1)	0.75 (0.7–0.79)
Seychelles	0.2 (0.2–0.3)	0.7 (0.5–0.9)	0.3 (0.3–0.4)	0.9 (0.7–1.1)	0.58 (0.52–0.65)
Sierra Leone	20.2 (15.5–26.6)	1.3 (1–1.7)	46.8 (36.2–60.9)	1.3 (1–1.6)	− 0.24 (− 0.37 to 0.11)
Singapore	9.6 (7.4–12.5)	0.6 (0.5–0.8)	16.3 (12.6–21.2)	0.8 (0.7–1.1)	1.07 (0.84–1.31)
Slovakia	131.6 (104.5–170.2)	6.4 (5.1–8.3)	151.5 (117.7–198.7)	8.9 (6.9–11.6)	1.28 (1.18–1.37)
Slovenia	75.2 (59.3–96.7)	9.8 (7.7–12.6)	71.5 (55.5–91.8)	12.6 (9.7–16.1)	0.95 (0.73–1.16)
Solomon Islands	0.8 (0.6–1)	0.6 (0.5–0.8)	2 (1.6–2.7)	0.7 (0.6–1)	0.71 (0.66–0.76)
Somalia	30.1 (23.4–39.4)	1 (0.8–1.4)	87.6 (68–113.1)	1.1 (0.8–1.4)	0.36 (0.21–0.5)
South Africa	202.7 (156.6–265.8)	1.3 (1–1.7)	361.7 (278.1–473.8)	1.5 (1.1–2)	0.47 (0.33–0.61)
South Sudan	26.6 (20.5–34.7)	1.2 (0.9–1.5)	44.6 (34.6–57.9)	1.2 (1–1.6)	0.44 (0.35–0.53)
Spain	1723.7 (1490.9–1991.5)	11.6 (10.1–13.4)	1453.6 (1157.5–1855.6)	11.7 (9.3–14.9)	0.17 (− 0.57 to 0.92)
Sri Lanka	59.3 (45.5–77.7)	0.8 (0.6–1.1)	85.5 (65.7–113.1)	1.1 (0.8–1.4)	1.51 (1.14–1.88)
Sudan	179 (140.9–233.8)	2.3 (1.8–3.1)	599.6 (468.3–795.9)	3.2 (2.5–4.3)	1.03 (0.97–1.09)
Suriname	4.2 (3.2–5.5)	2.6 (2–3.4)	6.8 (5.2–8.7)	3.2 (2.4–4.1)	0.6 (0.53–0.67)
Sweden	593.8 (483.9–707.2)	20.2 (16.5–24.1)	683.9 (556.4–809.5)	21.1 (17.2–25)	0.03 (− 0.11 to 0.17)
Switzerland	371 (290.2–479.1)	14.1 (11–18.2)	427.5 (335–547.5)	15.4 (12.1–19.7)	0.16 (0.07–0.25)
Syrian Arab Republic	120.4 (94.5–157.2)	2.5 (2–3.3)	162.8 (128.5–210.5)	3.2 (2.5–4.1)	1.01 (0.84–1.18)
Taiwan (Province of China)	75.9 (57.6–102.8)	0.8 (0.6–1.1)	86.4 (65.6–115.9)	1.1 (0.9–1.5)	2.35 (1.58–3.13)
Tajikistan	78.2 (60.8–101.7)	3.7 (2.9–4.8)	179.4 (139.8–231.9)	4.3 (3.4–5.6)	0.37 (0.22–0.53)
Thailand	151.8 (115.7–198.2)	0.6 (0.4–0.8)	162.9 (125.9–214.7)	0.8 (0.6–1)	0.77 (0.71–0.83)
Timor–Leste	1.8 (1.4–2.4)	0.6 (0.4–0.8)	3.9 (3–5.2)	0.7 (0.5–0.9)	0.66 (0.61–0.72)
Togo	16 (12.3–20.6)	1.2 (0.9–1.5)	47.3 (36.5–60.3)	1.4 (1.1–1.8)	0.49 (0.42–0.56)
Tokelau	0 (0–0)	0.8 (0.6–1)	0 (0–0)	0.9 (0.7–1.1)	0.32 (0.23–0.41)
Tonga	0.2 (0.2–0.3)	0.6 (0.4–0.8)	0.3 (0.2–0.4)	0.7 (0.6–1)	0.76 (0.7–0.82)
Trinidad and Tobago	14.9 (11.5–19.8)	3 (2.3–4)	18.1 (14.1–24.2)	3.6 (2.8–4.9)	0.48 (0.43–0.54)
Tunisia	85.7 (66.8–111.4)	2.5 (1.9–3.2)	147.1 (113.7–189.4)	3.4 (2.6–4.4)	1 (0.97–1.04)
Türkiye	673.1 (519.4–881.7)	2.8 (2.2–3.7)	1078.1 (847.6–1364.9)	3.4 (2.7–4.3)	0.57 (0.19–0.95)
Turkmenistan	64.9 (50.4–82.7)	4.2 (3.3–5.4)	108 (82.4–140.9)	5.2 (4–6.8)	0.67 (0.58–0.76)
Tuvalu	0 (0–0)	0.7 (0.5–0.9)	0 (0–0.1)	0.9 (0.7–1.2)	0.69 (0.65–0.72)
Uganda	74.2 (57.1–96.2)	1.2 (0.9–1.5)	245.4 (190.7–318.5)	1.4 (1.1–1.9)	0.68 (0.61–0.75)
Ukraine	609.7 (464.2–802.5)	3.2 (2.4–4.2)	623.7 (479.1–825)	4.5 (3.5–6)	1.17 (0.89–1.45)
United Arab Emirates	34.2 (26.4–45.9)	3.6 (2.8–4.8)	227.6 (172.6–300)	5.7 (4.3–7.5)	1.51 (1.41–1.61)
United Kingdom	3015.9 (2407.7–3785.2)	14.4 (11.5–18.1)	3734.4 (2963.2–4644.4)	17.2 (13.6–21.4)	− 0.23 (− 0.5 to 0.03)
United Republic of Tanzania	116 (90.7–147.5)	1.2 (0.9–1.5)	339.2 (267.6–447.7)	1.5 (1.1–1.9)	0.64 (0.57–0.72)
United States of America	17,814.3 (14,153.5–22,197.1)	17.4 (13.9–21.7)	19,680.7 (15,611.3–24,453.8)	17.7 (14–22)	0.02 (− 0.14 to 0.18)
United States Virgin Islands	1.1 (0.9–1.5)	2.9 (2.2–3.7)	0.8 (0.6–1.1)	3.6 (2.8–4.7)	0.61 (0.55–0.67)
Uruguay	46.6 (36–60)	4.1 (3.2–5.3)	60.6 (46.2–81.2)	5.1 (3.9–6.8)	0.76 (0.7–0.81)
Uzbekistan	317.7 (247.8–404.1)	3.7 (2.9–4.7)	713.2 (555.6–924.9)	5.2 (4–6.7)	0.96 (0.85–1.06)
Vanuatu	0.4 (0.3–0.5)	0.6 (0.5–0.8)	1 (0.7–1.3)	0.8 (0.6–1)	0.53 (0.51–0.55)
Venezuela (Bolivarian Republic of)	78.9 (60.1–102.5)	1 (0.8–1.3)	88.5 (66.5–121.6)	0.9 (0.7–1.3)	0.09 (− 0.09 to 0.27)
Vietnam	158.5 (121.1–208.7)	0.6 (0.4–0.7)	295.7 (224.4–395.3)	0.8 (0.6–1)	0.96 (0.91–1.02)
Yemen	108.9 (83.9–139.3)	2.4 (1.8–3)	429.2 (331.6–557.8)	3.1 (2.4–4.1)	1.03 (0.96–1.1)
Zambia	39.1 (30.7–50.4)	1.3 (1–1.7)	135.2 (105.4–174.7)	1.7 (1.3–2.2)	0.97 (0.89–1.06)
Zimbabwe	56.8 (44.9–74.1)	1.4 (1.1–1.9)	95 (73.2–123.5)	1.5 (1.2–1.9)	0.41 (0.23–0.58)

At the national and regional levels, only 21 out of 204 countries or regions exhibited a decreasing incidence trend (EAPC < 0). The most significant increase was observed among young individuals in China (EAPC = 3.34; 95% CI, 2.65 to 4.03), followed by Taiwan (province of China) (EAPC = 2.35; 95% CI, 1.58 to 3.13). Finland recorded the largest decline across all GBD countries (EAPC =  − 1.67; 95% CI, − 2.12 to − 1.21), with age-standardized rates (ASRs) for young Finnish adults in 2021 at 18.4 per 100,000, down 18.94% from 22.7 per 100,000 in 1990 (Fig. 1C, Table 1). Overall, ASRs remained high in Western countries, with Canada reporting the highest ASR globally between 1990 and 2021 (39.2 per 100,000 in 1990 and 34 per 100,000 in 2021), while Mexico had the lowest ASR in 2021 at 0.2 per 100,000 (Fig. 1A, Table 1).

Incidence, mortality, and DALY trends from 1990 to 2021

This study conducted a comprehensive analysis of IBD trends among individuals aged 15–39 years across 204 countries and regions from 1990 to 2021. Significant regional and gender differences were observed in morbidity, mortality, and DALYs. Globally, the age-standardized incidence rate (ASIR) showed a slow upward trend, with an EAPC of 0.33 (95% CI, 0.19 to 0.48) during this period. East Asia, Southeast Asia, and Oceania exhibited the most pronounced increases (EAPC = 2.59; 95% CI, 2.03 to 3.16), surpassing other regions. Conversely, high-income areas experienced a slower upward trend (EAPC = 0.21; 95% CI, 0.01 to 0.41), with declines noted in specific high-income countries, including Italy (EAPC =  − 0.66; 95% CI, − 0.84 to − 0.47), Canada (EAPC =  − 0.79; 95% CI, − 1.17 to 0.4), and Iceland (EAPC =  − 0.87; 95% CI, − 1.02 to 0.71) (Supplement Table 5.1–5.3).

In 2021, ASIR was lowest in sub-Saharan Africa, East Asia, South Asia, and Oceania (1.3 per 100,000), while Latin America and the Caribbean reported a slightly higher ASIR of 1.6 per 100,000. The ASIR exceeded 3 per 100,000 in most other regions. Notably, the sex difference in ASIR was not significant among individuals aged 15–39 years. Globally, the age-standardized mortality rate (ASMR) for IBD declined (EAPC =  − 0.26; 95% CI, − 0.33 to − 0.20), with the largest decrease in East Asia (EAPC =  − 1.98; 95% CI, − 2.19 to − 1.77) and an increase observed in sub-Saharan Africa (EAPC = 0.66; 95% CI, 0.59 to 0.72), where mortality rates were nearly double those of other regions (0.2 per 100,000). Notably, gender differences emerged, with mortality decreasing in men (EAPC =  − 0.7; 95% CI, − 0.78 to − 0.61) but increasing in women (EAPC = 0.16; 95% CI, 0.09 to 0.22). Young men experienced a significant decline in mortality from 1990 to 2021 in Central and Eastern Europe (CEE) and Central Asia (EAPC =  − 1.64; 95% CI, − 2.06 to − 1.22), while the most pronounced decline among young women was noted in East Asia (EAPC =  − 2.88; 95% CI, − 3.12 to − 2.63) (Supplement Table 6.1–6.3).

Trends in DALYs also exhibited a downward trajectory, with an EAPC of − 0.2 (95% CI, − 0.27 to − 0.14) annually. Similar to mortality patterns, the largest declines in DALYs were observed in East Asia, Southeast Asia, and Oceania (EAPC =  − 0.83; 95% CI, − 0.99 to − 0.67), whereas sub-Saharan Africa experienced a notable increase (EAPC = 0.63; 95% CI, 0.57 to 0.69). However, DALYs in high-income areas (23.6 per 100,000) remained significantly higher than in other regions. From a gender perspective, the decline in disability-adjusted life years (DALYs) among males aged 15–39 is most pronounced in Central and Eastern Europe and Central Asia (EAPC =  − 0.89; 95% CI, − 1.17 to − 0.61). In contrast, the most significant decline for females occurs in East Asia (EAPC =  − 1.02; 95% CI, − 1.25 to − 0.79), reflecting similar regional patterns in mortality trends. Globally, female DALYs show a slight upward trend (EAPC = 0.01; 95% CI, − 0.05 to 0.08), while male DALYs are gradually decreasing (EAPC =  − 0.44; 95% CI, − 0.51 to − 0.36) (Fig. 2, Supplement Table 7.1–7.3).

Fig. 2.

Trends in age-standardized rates of inflammatory bowel disease in children and adolescents per 100,000 population across continents from 1990 to 2021. Abbreviation: IBD, inflammatory bowel disease; ASIR, age-standardized incidence rate; ASMR, age-standardized mortality rate; DALYs, disability-adjusted life years; EAPC, estimated annual percentage change

IBD disease burden and SDI

The age-standardized incidence rate (ASIR) of IBD exhibited a significant correlation with the sociodemographic index (SDI) across countries. In the high SDI quintile, the incidence rate among the 15–39 age group in 2021 (13.6 cases per 100,000; 95% CI, 10.9 to 16.9) was notably higher than the global average, while incidence rates in lower SDI quintiles fell below the global incidence. However, the increasing trend in high SDI regions (EAPC = 0.08; 95% CI, − 0.09 to 0.24) was slower than the global trend, whereas the remaining SDI quintiles exhibited more pronounced increases. Although ASRs in the mid-SDI region were not significantly higher or lower than in other areas (2.3 per 100,000; 95% CI, 1.8 to 3.1), the upward trend was most substantial (EAPC = 1.97; 95% CI, 1.72 to 2.22) (Table 2).

Table 2.

Incident cases and age-standardized incidence of IBD in children and young adults in 1990 and 2021 and its temporal trends from 1990 to 2021

Location	Num_1990	ASR_1990	Num_2021	ASR_2021	EAPC_CI
High SDI	45,103.3 (37,452.8–54,474)	13 (10.8–15.7)	48,202.9 (38,440.9–59,637.8)	13.6 (10.9–16.9)	0.08 (− 0.09 to 0.24)
High-middle SDI	13,089.7 (10,479.9–16,509)	2.9 (2.3–3.6)	15,596.1 (12,202.4–20,398.4)	3.5 (2.8–4.6)	0.96 (0.68–1.23)
Middle SDI	10,425.5 (8085.3–13,728.1)	1.4 (1.1–1.8)	21,597.6 (16,636.7–28,354.4)	2.3 (1.8–3.1)	1.97 (1.72–2.22)
Low-middle SDI	12,711.8 (9846.3–16,524)	2.8 (2.2–3.6)	28,051.2 (21,730.4–36,696.6)	3.5 (2.7–4.6)	0.82 (0.7–0.94)
Low SDI	3545.9 (2717.7–4605.3)	1.9 (1.5–2.5)	9802.2 (7599–12,803.6)	2.2 (1.7–2.9)	0.55 (0.46–0.64)

Examining the annual time series from 1990 to 2021, the incidence in higher SDI regions showed a trend from increasing to decreasing in several areas, excluding Eastern Europe, while regions with moderate or lower SDI continued a slow increase. The DALY rate in North Africa and the Middle East remained stable, whereas high-income Asia–Pacific, North America, Europe, Central Asia, and the Caribbean exhibited an initial increase followed by a decline from 1990 to 2021. Conversely, DALY rates in Central and Tropical Latin America showed a degree of increase (Fig. 3D). At the national level, fitted curves indicated a strong positive correlation between incidence rates and SDI in 2021, with countries or regions exhibiting SDI values above 0.75 corresponding to the top 28 incidence rates (Fig. 3A). The relationship between DALYs and SDI in 2021 revealed contrasting patterns; Guinea-Bissau reported the highest DALYs despite having an SDI value of only 0.353. Additionally, Gambia, Mali, Togo, and Senegal, with SDI values around or below 0.4, ranked among the top ten countries for DALYs worldwide (Fig. 3B). Figure 3B illustrates that DALYs were significantly higher in countries with both high SDI and low SDI values.

Fig. 3.

Age-standardized incidence rate (A) and disability-adjusted life years (B) of children and adolescents with inflammatory bowel disease in 204 countries and regions as shown by the sociodemographic index from 1990 to 2021. Age-standardized incidence rate (C) and disability-adjusted life years (D) of children and adolescents with inflammatory bowel disease in 22 regions and regions as shown by the sociodemographic index from 1990 to 2021. Abbreviation: ASIR, age-standardized incidence rate; DALYs, disability-adjusted life years; IBD, inflammatory bowel disease; SDI, for Social Population Index

Incidence rate and DALY trends by gender groups based on Joinpoint regression analysis

We conducted Joinpoint regression analysis on global age-standardized incidence rates (ASIR) and disability-adjusted life years (DALYs) from 1990 to 2021. For women, the incidence showed an increase from 1990 to 2000 (APC = 0.6933; 95% CI, 0.6047 to 0.7949), with a more pronounced rise between 2005 and 2010 (APC = 2.6901; 95% CI, 2.5395 to 2.8680). There was a decline in incidence from 2000 to 2005 (APC =  − 0.2889; 95% CI, − 0.5617 to − 0.0822) and a significant decrease from 2010 to 2019 (APC =  − 1.3831; 95% CI, − 1.5034 to − 1.2982) (Fig. 4A, Supplement Table 1). The male incidence rate increased significantly between 1995 and 1999 (APC = 1.5859; 95% CI, 1.2892 to 1.9290) compared to 1990 to 1995 (APC = 0.4588; 95% CI, 0.1508 to 0.6519) (Fig. 4B, Supplement Table 1). Overall, the incidence showed a consistent yearly increase (AAPC = 0.2213; 95% CI, 0.1888 to 0.2487) (Supplement Table 2).

Fig. 4.

Joinpoint regression analysis of the sex-specific age-standardized incidence rate of children and adolescents with IBD from 1990 to 2021. A Age-standardized incidence rate for females. B Age-standardized incidence rate for males. C Disability-adjusted life years for females. D Disability-adjusted life years for males

Regarding DALYs, we noted a slow increase among women from 1990 to 2001 (APC = 0.2228; 95% CI, 0.1318 to 0.4133), with a rise from 2006 to 2010 (APC = 1.2348; 95% CI, 0.7359 to 1.7645) and a gradual increase from 2018 to 2021 (APC = 0.3880; 95% CI, − 0.2259 to 1.2241) (Fig. 4C, Supplement Table 3). In contrast, the DALY rate for men increased from 1990 to 1993 (APC = 1.0631; 95% CI, 0.5560 to 2.0402) and then decreased from 1993 to 2000 (APC =  − 0.1073; 95% CI, − 0.3976 to 0.0840) and significantly from 2000 to 2005 (APC =  − 1.1122; 95% CI, − 1.7878 to − 0.7660). This downward trend continued from 2010 to 2015 (APC =  − 1.3868; 95% CI, − 1.9904 to − 0.9972) and slowed from 2015 to 2021 (APC =  − 0.6054; 95% CI, − 0.88 to 0.3179) (Fig. 4D, Supplement Table 3). Notably, DALY rates in males aged 15–39 showed a consistent annual decline (AAPC =  − 0.3537; 95% CI, − 0.3964 to − 0.3012), while females exhibited a slight annual increase (AAPC = 0.0120; 95% CI, − 0.0278 to 0.0510) (Supplement Table 4).

Prediction of the incidence from 2022 to 2040

We employed a Bayesian age-period-cohort (BAPC) model to predict the incidence of IBD among individuals aged 15–39 globally from 2022 to 2040. The direct predictions for various age groups of men indicate that the incidence for those aged 15–19, 20–24, and 25–29 will initially decrease before increasing again from 2022 to 2040, while the incidence for those aged 35–39 is expected to continue rising. A similar trend is observed in the predictions for women (Fig. 5).

Fig. 5.

Change trend of incidence rate of inflammatory bowel disease for men in children and adolescents in different age stages from 1990 to 2040

Discussion

Our study systematically analyzed the incidence, mortality, geographical disparities in disability-adjusted life years (DALYs), and gender differences in individuals aged 15–39 years with a high incidence of inflammatory bowel disease (IBD), utilizing data from GBD2021. This analysis underscores significant epidemiological differences in IBD and highlights an urgent need for targeted screening and treatment strategies in key regions. By addressing the gaps in current literature regarding the global burden of IBD in this age group, we present a comprehensive view of the disease’s trends, particularly when comparing our findings to those derived from GBD2019 and earlier data [19, 22]. The results indicate that developing countries require heightened attention regarding IBD incidence, particularly as DALYs increase and health inequities worsen amidst global development disparities.

Although recent studies have utilized GBD2021 data to describe global IBD trends [23], there remains a lack of specific analyses focused on high-risk age groups and predictive trends for future disease burdens. The novelty of this study lies in its focus on the disease burden of IBD in the 15–39 age group. Traditional IBD burden studies have typically concentrated on older populations, overlooking the significant impact of IBD on younger individuals. Emerging evidence suggests that young adults are increasingly at high risk for IBD [24], with a younger age of onset being observed. Notably, individuals aged 15–39 are in a critical phase of life, often serving as the primary breadwinners for their families and key contributors to social productivity.

Patients in this age group face not only long-term health challenges but also significant impacts on their quality of life, work capacity, and income. The social, economic, and familial roles of individuals aged 15–39 make the burden of IBD in this group particularly heavy. Beyond the medical, economic, and psychological pressures on patients themselves, their family members often assume caregiving responsibilities, further straining the household’s financial stability. Specifically, illness-related absences, reduced work capacity, or the inability to work full-time can lead to long-term loss of family income. These factors significantly exacerbate the socio-economic burden of IBD in this group, highlighting its unique impact compared to older populations, which are crucial for informing public health policies and governmental initiatives [25, 26].

Our predictions for the incidence of IBD in five age groups in the 15–39 age group up to 2040 show a slight increase. Current research exploring cognitive behavioral therapy, dietary modifications, and biologic treatments has shown promise in managing IBD among young patients, further contributing to the control of incidence rates [27–31]. As a chronic and often debilitating disease, IBD poses significant treatment challenges and financial burdens [32, 33]. Notably, declines in DALYs and age-standardized mortality rates (ASMRs) in high and medium socio-demographic index (SDI) countries, particularly in East Asia, reflect the impact of advanced treatment strategies and new drug introductions [30, 31]. However, the rapidly increasing incidence of IBD in newly industrialized countries, such as China, raises concerns. The incidence in this age group has surged from 0.7 cases per 100,000 in 1990 to 1.6 cases per 100,000 in 2021, attributed to urbanization, industrialization, and dietary changes, alongside improved diagnostic capabilities [19, 34]. This phenomenon is not unique to China; similar trends can be observed in other emerging industrialized nations facing analogous challenges. Urbanization often disrupts gut microbiomes and increases the consumption of ultra-processed foods, both of which are associated with heightened IBD risk [35, 36]. While Western countries have stabilized in their IBD incidence rates, the epidemiology of IBD can be segmented into four stages: emergence, accelerated incidence, compound prevalence, and prevalence balance. Western nations are largely in the third stage, whereas emerging industrialized countries remain in the second stage [37].

Of particular concern is the observation that low SDI countries, although experiencing only a slow increase in incidence, face some of the highest mortality and DALY rates globally [37]. In severely underdeveloped nations like Guinea-Bissau and Mali, effective diagnosis and treatment of IBD are severely lacking, compounded by food insecurity and inadequate social support systems [38]. Consequently, countries at various stages of development must adopt tailored management strategies to address the burden of IBD. High SDI countries need to prepare for an aging IBD population [32], while medium SDI countries may require updated strategies to manage the increasing morbidity among younger individuals. Low SDI countries face the dual challenge of high mortality and the societal impact of DALYs. Furthermore, the interplay of gender and regional differences reveals critical disparities, particularly in mortality and DALYs. The significant increase in mortality and DALYs among women in sub-Saharan Africa contrasts with the pronounced declines observed in men in Central and Eastern Europe and Central Asia. These discrepancies may stem from genetic factors as well as disparities in access to healthcare and nutrition [39, 40].

Overall, the findings of our analysis provide new insights for the field of public health, offering valuable guidance for policymakers, healthcare organizations, and social security systems on the burden of IBD among young adults. The disease burden in this group is often underestimated, particularly when shaping public health policies, as traditional analyses may overlook the unique needs of young adults. Thus, our study addresses the gap in the literature regarding the burden of disease in IBD patients aged 15–39 and provides a critical foundation for future research on strategies to reduce this burden. Specifically, our results are highly relevant for promoting family-based social support policies, improving early diagnosis and treatment of young adults with IBD, and mitigating their socio-economic burden.

However, our study does have limitations. It heavily relies on the accuracy of the GBD database, which may present challenges in data completeness, especially in underdeveloped countries with insufficient healthcare infrastructure. Additionally, we were unable to obtain specific data on ulcerative colitis (UC) and Crohn’s disease (CD), which hampers our ability to analyze the nuanced risk factors associated with IBD. Future studies should aim to synthesize newly published epidemiological data to provide a more comprehensive understanding of IBD’s impact across different demographics and regions.

Conclusion

Over the past three decades, the incidence of inflammatory bowel disease (IBD) among individuals aged 15–39 has shown a general upward trend. While incidence rates in Western countries have stabilized, young people in newly industrialized nations are experiencing a rapid increase in IBD cases. We predict that this trend will persist with little improvement by 2040. Additionally, the rising mortality rates and DALYs associated with IBD in underdeveloped regions highlight the escalating global burden of the disease. Integrating risk factors into future GBD research models could yield more relevant insights into this issue. Our study emphasizes the importance of focusing on young populations to alleviate the burden of IBD and optimize the allocation of medical resources, as well as to inform public health policies and address regional disparities.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contribution

"LC, YX, YL and XL conceived the project; investigation, LC and YX; Data collection, LC, YX, and FA; Data analysis, YX and LC; writing—original draft preparation, LC, YX, YL and XL; writing—review and editing, XL, YL, and SS; supervision, XL, YL and SS. All authors have read and agreed to the published version of the manuscript."

Funding

This work was supported in part by grants from The National Natural Science Foundation of China (82172766).

Data availability

Data can be obtained from the Global Health Data Exchange Global Burden of Disease Results Tool (https://ghdx.healthdata.org/gbd-results-tool).

Declarations

Ethics approval and consent to participate

The data analyzed in this study is publicly available from existing, published Global Burden of Disease (GBD) study from 1990 to 2021. Therefore, informed consent was waived.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.