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. 2024 Nov 6;137(23):2851–2859. doi: 10.1097/CM9.0000000000003345

Growing burden of inflammatory bowel disease in China: Findings from the Global Burden of Disease Study 2021 and predictions to 2035

Ziqing Yu 1, Gechong Ruan 1, Xiaoyin Bai 1, Yinghao Sun 1, Hong Yang 1,✉, Jiaming Qian 1
Editor: Yuanyuan Ji
PMCID: PMC11649283  PMID: 39501850

Abstract

Background:

Inflammatory bowel disease (IBD) imposes a significant economic and social burden in China. We aim to assess the epidemiological trends of IBD in China, and to predict the burden in the near future.

Methods:

The incidence, mortality, prevalence, and disability-adjusted life year (DALYs) of IBD from 1990 to 2021 were obtained from Global Burden of Disease Study 2021. Estimated annual percentage change (EAPC), average annual percent change, total percent change, and age-period-cohort model were used to access trends. Bayesian age–period–cohort model was utilized to predict the risk of incidence and mortality.

Results:

In 2021, IBD affected 168,077 people in China, with 24,941 new cases and 5640 deaths. The age-standardized rate (ASR) of incidence and death was 1.4 and 0.3, respectively. The incidence and prevalence in China were lower than the global and high socio-demographic index (SDI) regions, but the ASR of incidence and prevalence (EAPC: 2.93 and 2.54, respectively) had rapidly increased from 1990 to 2021. The ASR of death and DALYs had significantly decreased (EAPC: −3.05 and −2.93, respectively). Middle-aged and elderly populations faced a severe burden of incidence and prevalence, while the elderly population faced a severe mortality burden. It is projected that by 2035, the ASR of incidence will continue to rise, whereas the death rate will continue to decline.

Conclusions:

The burden of IBD in China is serious and increasingly severe. Establishing a comprehensive disease management system in China will help better control the medical burden of IBD.

Keywords: Inflammatory bowel disease, Incidence, Prevalence, Global Burden of Disease, Disease burden, China

Introduction

Inflammatory bowel disease (IBD) is a chronic, recurrent disease with significant individual and societal costs. It may result from an abnormal immune response to environmental factors in a genetically susceptible host, and presents with various clinical symptoms such as rectal bleeding, abdominal pain, diarrhea, and weight loss.[1] As an incurable chronic disease, IBD requires lifelong care and medications.[2] In patients with a long disease course, the proportion of chronic continuous pattern was the highest.[3] Meanwhile, the risk of multiple cancers, including digestive system tumors, was also significantly increased in the IBD population in China.[4] This inevitably leads to IBD occupying more medical resources and increasing the difficulty of disease management. It is estimated that the total expenditure for 166,000 hospitalized IBD patients in China in 2018 was $ 426 million, which severely affects patients’ quality of life while posing further challenges to China’s healthcare system.[5] Furthermore, the emergence of new and increasingly sophisticated medications and disease management models exacerbated the financial burden caused by IBD.[2] Properly assessing the epidemiological trends of IBD in China helps achieve disease control, management, and prevention, thereby saving medical resources and government financial expenditure.

The Global Burden of Disease (GBD) study, which includes 328,938 data sources, is a comprehensive global observational epidemiological study that provides valuable resources for assessing health levels and trends. The earliest GBD study began in the early 1990s and was included in the Development Report 1993: Investing in Health.[6] The latest GBD study assesses data from 1990 to 2021 for 204 countries and regions, 371 diseases and injuries, and 88 risk factors.[7] This provides crucial data support for health department decision-makers, clinicians, and researchers. Previous studies had identified the changing burden and regional differences of IBD.[8,9] The incidence of IBD had reached a stable level in high-income countries, while the globalization at the turn of the 21st century had led to the rapid economic development of emerging industrialized countries such as China, and the incidence of IBD in China had also increased accordingly.[10,11] Since 1956, the prevalence of IBD in China had risen significantly, transitioning from a rare disease to a common disease. Facing the continuously changing forms of age, time, region, and development differences, a timely and systematic analysis of the burden of IBD in China helps in the evaluation, management, and control of the disease. We utilized the latest estimates from the GBD study in 2021 to assess the burden of IBD in China and the trends in epidemiological changes, and we predicted the disease burden in the short-term future. Comprehensive elucidation of the disease burden and trends of IBD in China is of valuable significance for macro-level strategic planning and micro-level research and application, thereby helping to save China’s relatively precious medical resources to meet the people’s growing needs for a better life.

Methods

Study design

The GBD study is a project dedicated to assessing the impact of diseases, disabilities, and risk factors on population health globally and regionally, aiming to provide comprehensive data support for public health decision-making. Information on annual IBD incidence, mortality, prevalence, and disability-adjusted life years (DALYs) from 1990 to 2021, categorized by age, sex, region, and country, was collected in the GBD Results tool (https://vizhub.healthdata.org/gbd-results/). The data and results are presented in numerical or rate, accompanied by 95% uncertainty intervals (UIs). Mortality estimates are expressed as the number of deaths per 100,000 population and the age-standardized rate (ASR) due to IBD. DALYs are calculated by summing the years lived with disability and years of life lost, serving as a comprehensive metric for assessing the burden of disease.[12] We classified countries into five categories based on the socio-demographic index (SDI: high SDI, high-middle SDI, middle SDI, low-middle SDI, and low SDI).[13] The Supplementary Methods, http://links.lww.com/CM9/C199, provides detailed data retrieval methods for this study. IBD in GBD 2021 was identified based on the 10th revision of the International Classification of Diseases (ICD-10 codes: K50-K52, K52.8-K52.9; for ICD-9 codes: 555-556.9, 558-558.9, 569.5). In the reference case definition of IBD, cases included patients diagnosed with corresponding clinical symptoms through endoscopy, imaging studies, or biopsy, or cases identified from patient databases using an algorithm based on ICD codes. GBD 2021 also includes non-reference standard studies, such as cases directly extracted from patient databases without using verification algorithms. Prevalence estimates were extracted from the Institute for Health Metrics and Evaluation (IHME)-processed hospitalization discharge and claims data were excluded. Additionally, GBD 2021 incorporated high-quality systematic reviews from Canada and administrative data extracted using validated algorithms.[10,14] Detailed methodologies for GBD 2021 can be found on the official website (https://www.healthdata.org/gbd/methods-appendices-2021).

Statistical analysis

The ASR and the estimated annual percentage change (EAPC) were used to quantify the trends in incidence, mortality, prevalence, and DALYs of IBD.[15] Age standardization helps to compare different age structures or changes in the age structure of the same population over different periods. Direct standardization is conducted by multiplying the age-specific rate of each age group by the weight of the same age group in the selected standard population, summing these products, and then dividing by the total weight of the standard population. The standard population was based on the GBD 2021 standard population.[7] According to the WHO’s classification standards for age groups, we categorized individuals aged 45–59 years as middle-aged, those over 60 years as elderly, and those under 45 years as young people.[16] If the EAPC estimate and its 95% confidence interval (CI) are both greater than 0, the ASR is considered to be increasing, and vice versa.[17] We also used Joinpoint regression analysis, total percent change, and the Age-Period-Cohort model (APCM) to ensure the reliability of the trend estimates. Total percent change can be directly extracted from GBD 2021. Joinpoint regression analysis was utilized to assess the annual percentage change (APC) and average annual percent change (AAPC) of various disease burdens along with their corresponding 95% CI.[18,19] We also used the APCM to examine the age, period, and birth cohort-specific trends in China from 1990 to 2021 by the Age-Period Cohort Web Tool.[20,21] APCM, based on the Poisson distribution, decomposes the target analysis variable from three dimensions: age, period, and cohort, thereby better analyzing the risk of disease incidence or mortality across these dimensions. The period effect refers to changes in disease rates in a population due to human factors, such as advancements in disease diagnostic technology, screening, disease definition, and so on. The age effect is the effect of disease rates changing with age, and the cohort effect is the change in disease rates caused by different generations being exposed to varying degrees of risk factors. The main results of APCM include net drift, which represents the annual percentage change, and local drift, which represents the age-specific percentage change. The output also includes adjusted longitudinal age-specific rates for the reference cohorts, taking into account period bias and representing age effects. Period and cohort effects are expressed as relative risk of disease for each period and cohort. The choice of reference period and cohort is arbitrary and does not affect the interpretation of results. To further predict the short-term future trends of IBD based on the latest data, we obtained global population estimates (2017–2100) from the GBD database (https://ghdx.healthdata.org/record/ihme-data/global-population-forecasts-2017-2100). We used the Bayesian age-period-cohort (BAPC) model with nested Laplace approximation, based on the assumption of a relationship between incidence or mortality and age structure and population size, for prediction analysis.[22] The advantage of the BAPC model is that it directly approximates the posterior marginal distribution, does not require convergence diagnostics, and has sufficient accuracy. Compared with the generalized additive model, the smooth spline model, the Nordpred model, and Poisson regression, the BAPC model has higher accuracy in predicting the short- and medium-term burden.[23]

All statistical analyses and visualization were conducted using R-4.2.2 (R Foundation for Statistical Computing, Vienna, Austria), GraphPad Prism (9.5.1, GraphPad Software, CA, USA), and Joinpoint Trend Analysis Software (5.0, US National Cancer Institute, USA). A P value of less than 0.05 was considered statistically significant.

Ethical approval of studies and informed consent

The study did not involve any ethical problem and data collection was completed in accordance with the ethical regulations.

Results

Disease burden of IBD in China in 2021

In 2021, the prevalent cases of IBD in China was 168,077, with 24,941 new cases and 5640 deaths, resulting in a total of 136,932 DALYs [Table 1]. The 2021 age-standardized incident rate (ASIR) and age-standardized death rate (ASDR) were 1.4 (95% UI: 1.2–1.7) and 0.3 (95% UI: 0.3–0.4), respectively. The highest incidence was among the 50–54 years age group, with a relatively high ASIR among those aged 50–59 years [Figure 1A]. With increasing age, the death cases and the ASDR in China in 2021 both increased, indicating a severe mortality burden among middle-aged and elderly populations [Figure 1B]. The 50–54 years age group had the highest prevalent cases of IBD patients, and the number of female IBD patients was higher than that of males over 25 years old. With age, the age-standardized prevalent rate (ASPR) for both males and females increased until the age of 60 years [Figure 1C]. DALYs were generally higher among middle-aged and elderly populations, with the ASR of DALYs significantly rising after the age of 70 years [Figure 1D].

Table 1.

Disease burden of IBD in China and worldwide from 1990 to 2021.

Items 1990 2021 1990–2021
n (95% UI) ASR per 100,000 (95% UI) n (95% UI) ASR per 100,000 (95% UI) EAPC (95% CI) AAPC (95% CI) TPC (95% CI)
Incidence
China 8315.7 (7018, 10,181.6) 0.7 (0.6, 0.9) 24,941 (21,583, 29,821) 1.4 (1.2, 1.7) 2.93 (2.41, 3.46) 2.09 (1.46, 2.72) 0.89 (0.84, 0.94)
East Asia 8632.7 (7283.5, 10,588.2) 0.7 (0.6, 0.9) 25,532 (22,107, 30,530) 1.4 (1.2, 1.7) 2.88 (2.37, 3.4) 2.05 (1.49, 2.61) 0.87 (0.82, 0.92)
Global regions 199,235.9 (174,583.8, 232,676.2) 4.2 (3.7, 4.9) 375,140 (327,686, 436,925) 4.4 (3.9, 5.2) 0.29 (0.2, 0.38) 0.16 (0.07, 0.24) 0.05 (0.04, 0.07)
High SDI 104,710.9 (93,318.3, 120,553.5) 10.6 (9.5, 12.3) 158,046 (139,737, 180,170) 11.6 (10.1, 13.4) 0.33 (0.21, 0.46) 0.27 (0.22, 0.32) 0.09 (0.06, 0.11)
High-middle SDI 32,333.9 (28,390.3, 37,886.6) 3 (2.6, 3.5) 53,486 (46,612, 63,298) 3.3 (2.8, 3.9) 0.48 (0.33, 0.64) 0.29 (0.20, 0.38) 0.1 (0.07, 0.12)
Middle SDI 22,846.1 (19,540.7, 27,838.7) 1.6 (1.4, 1.9) 64,887 (56,016, 78,446) 2.4 (2.0, 2.9) 1.54 (1.38, 1.70) 1.37 (1.11, 1.62) 0.50 (0.48, 0.52)
Low-middle SDI 30,776.5 (26,407, 37,156.7) 3.6 (3.2, 4.3) 75,380 (64,725, 91,310) 4.3 (3.7, 5.1) 0.55 (0.49, 0.62) 0.54 (0.45, 0.62) 0.18 (0.16, 0.20)
Low SDI 8373.3 (7159.3, 10,141.8) 2.5 (2.2, 3.1) 23,065 (19,690, 27,960) 3 (2.6, 3.6) 0.57 (0.54, 0.61) 0.52 (0.46, 0.58) 0.17 (0.15, 0.20)
Death
China 4411.5 (2972.2, 5559.9) 0.7 (0.5, 0.9) 5640 (4395, 7497) 0.3 (0.3, 0.4) –3.05 (–3.42, –2.67) –2.65 (–2.79, –2.50) –0.56 (–0.69, –0.30)
East Asia 4592.1 (3149.1, 5757.7) 0.7 (0.5, 0.9) 5967 (4700, 7910) 0.3 (0.3, 0.4) –3.01 (–3.35, –2.66) –2.63 (–2.88, –2.38) –0.56 (–0.68, –0.30)
Global regions 21,417.7 (18,422.8, 23,612.6) 0.6 (0.5, 0.7) 42,423 (37,537, 46,502) 0.5 (0.5, 0.6) –0.31 (–0.48, –0.14) –0.49 (–0.68, –0.29) –0.13 (–0.22, –0.02)
High SDI 7616.8 (7023.7, 8006.5) 0.7 (0.7, 0.7) 19,080 (16,203, 20,658) 0.8 (0.7, 0.9) 0.84 (0.52, 1.17) 0.39 (0.07, 0.70) 0.13 (0.07, 0.20)
High-middle SDI 4692.1 (4305.2, 5212.5) 0.5 (0.5, 0.6) 7445 (6481, 8795) 0.4 (0.3, 0.5) –0.99 (–1.09, –0.89) –0.82 (–1.17, –0.47) –0.24 (–0.32, –0.13)
Middle SDI 4902.5 (3456.1, 5923.3) 0.5 (0.3, 0.6) 7911 (6468, 9100) 0.3 (0.3, 0.4) –1.67 (–1.8, –1.53) –1.48 (–1.71, –1.26) –0.36 (–0.49, –0.14)
Low-middle SDI 2884.3 (2101.7, 3511.7) 0.5 (0.3, 0.6) 5211 (4305, 6489) 0.4 (0.3, 0.5) –0.77 (–0.82, –0.71) –0.74 (–0.96, –0.51) –0.2 (–0.41, 0.04)
Low SDI 1300.8 (917.9, 1610.7) 0.5 (0.4, 0.7) 2741 (1910, 3422) 0.5 (0.3, 0.6) –0.42 (–0.49, –0.35) –0.41 (–0.56, –0.25) –0.12 (–0.26, 0.05)
Prevalence
China 62,097.9 (52,445.9, 75,050.2) 5.6 (4.7, 6.7) 168,077 (141,521, 201,684) 9.2 (7.8, 11.0) 2.54 (1.91, 3.17) 1.62 (1.10, 2.14) 0.64 (0.58, 0.70)
East Asia 64,806.6 (54,671.1, 78,247.0) 5.6 (4.8, 6.7) 172,201 (145,043, 206,864) 9.1 (7.7, 10.9) 2.49 (1.87, 3.11) 1.57 (1.19, 1.95) 0.61 (0.67, 0.56)
Global regions 2,170,243.3 (1,892,401.8, 2,522,561.3) 48 (41.9, 55.8) 3,830,119 (3,312,834, 4,511,555) 44.9 (38.8, 52.9) –0.13 (–0.25, 0) –0.22 (–0.27, –0.17) –0.07 (–0.08, –0.05)
High SDI 1,306,709.5 (1,155,692.1, 1,487,814.6) 129.5 (114.4, 147.6) 2,012,478 (1,755,438, 2,316,531) 132.8 (115.0, 154.3) 0.08 (–0.10, 0.26) 0.06 (0.01, 0.11) 0.02 (–0.01, 0.05)
High-middle SDI 374,805.8 (323,916.7, 442,307.8) 35.3 (30.6, 41.6) 541,766 (462,605, 647,488) 31.6 (27.1, 37.9) –0.15 (–0.31, 0.02) –0.37 (–0.46, –0.28) –0.1 (–0.12, –0.08)
Middle SDI 194,215.3 (163,798.4, 235,106.1) 14 (11.9, 16.9) 544,518 (460,464, 659,902) 19.6 (16.6, 23.8) 1.34 (1.19, 1.50) 1.12 (0.82, 1.43) 0.4 (0.38, 0.42)
Low-middle SDI 228,004.4 (192,791.1, 273,562.9) 28 (23.7, 33.5) 561,436 (475,598, 680,836) 32.5 (27.5, 39.1) 0.66 (0.58, 0.73) 0.47 (0.36, 0.58) 0.16 (0.14, 0.18)
Low SDI 64,105.3 (53,897.8, 77,409.2) 20.7 (17.5, 25.0) 166,793 (140,414, 203,986) 22.8 (19.4, 27.6) 0.41 (0.36, 0.46) 0.32 (0.24, 0.39) 0.11 (0.07, 0.14)
DALYs
China 162,185.8 (115,399.6, 206,768.3) 18.4 (12.7, 23.1) 136,932 (109,830, 171,866) 7.7 (6.2, 9.6) –2.93 (–3.23, –2.64) –2.86 (–3.05, –2.67) –0.58 (–0.69, –0.39)
East Asia 167,496.3 (120,085.3, 212,704.4) 18.3 (12.8, 23.0) 143,569 (116,156, 180,091) 7.8 (6.3, 9.6) –2.89 (–3.16, –2.62) –2.84 (–3.04, –2.63) –0.58 (–0.69, –0.39)
Global regions 948,860.8 (808,100.6, 1,096,717) 21.5 (18.5, 24.8) 1,510,784 (1,308,508, 1,750,363) 18.1 (15.7, 20.9) –0.52 (–0.60, –0.43) –0.57 (–0.68, –0.46) –0.16 (–0.22, –0.1)
High SDI 343,883.2 (283,244.4, 418,649) 33.7 (27.6, 41.2) 599,038 (501,803, 711,056) 35 (28.3, 43.0) 0.31 (0.10, 0.51) 0.12 (–0.06, 0.29) 0.04 (0.01, 0.07)
High-middle SDI 194,740.7 (169,862.5, 224,657.7) 19.3 (16.9, 22.3) 229,281 (197,044, 267,170) 13.1 (11.2, 15.2) –1.4 (–1.49, –1.31) –1.21 (–1.44, –0.98) –0.32 (–0.39, –0.25)
Middle SDI 205,675.2 (155,790.4, 244,159.9) 15.7 (11.7, 18.4) 285,305 (240,198, 329,976) 10.9 (9.2, 12.6) –1.23 (–1.28, –1.17) –1.17 (–1.33, –1.02) –0.3 (–0.42, –0.14)
Low-middle SDI 141,892.8 (112,360.1, 174,778.2) 17.6 (13.7, 21.3) 257,852 (210,807, 312,042) 15.4 (12.6, 18.7) –0.45 (–0.49, –0.41) –0.43 (–0.51, –0.35) –0.13 (–0.26, 0.03)
Low SDI 61,703 (45,765.1, 79,566.2) 19.2 (14.3, 23.6) 138,076 (98,060, 170,355) 18.0 (13.3, 21.8) –0.25 (–0.30, –0.20) –0.21 (–0.3, –0.13) –0.06 (–0.21, 0.10)
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AAPC: Average annual percent change; ASR: Age-standardized rate; CI: Confidence interval; DALYs: Disability-adjusted life years; EAPC: Estimated annual percentage change; IBD: Inflammatory bowel disease; SDI: Socio-demographic Index; TPC: Total percentage change; UI: Uncertainty interval.

Figure 1.

Figure 1

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Age patterns by sex in 2021 of number and age-specific rates of incidence, deaths, prevalence, and DALYs due to IBD in China. Age patterns by sex in 2021 of number and age-specific rates of incidence (A), deaths (B), prevalence (C), and DALYs (D) due to IBD in China. Error bars indicate the 95% UI for the number or ASRs. ASR: Age-standardized rate; ASIR: Age-standardized incident rate; ASDR: Age-standardized death rate; ASPR: Age-standardized prevalent rate; DALYs: Disability-adjusted life years; IBD: Inflammatory bowel disease; UI: Uncertainty interval.

According to the SDI classification, the regions with the highest ASIR, ASDR, ASPR, and ASR of DALYs were all high-SDI regions in 2021 [Table 1]. The ASIR, ASDR, ASPR, and ASR of DALYs for IBD in China in 2021 were similar to those in East Asia but lower than the global average and the high SDI region [Table 1].

Trends of IBD burden in China from 1990 to 2021

Between 1990 and 2021, the ASIR of IBD in China gradually increased (EAPC: 2.93, 95% CI: 2.41, 3.46), and the ASPR also showed an upward trend (EAPC: 2.54, 95% CI: 1.91, 3.17). The ASDR and ASR of DALYs, however, significantly decreased (EAPC: −3.05, and −2.93, respectively) [Table 1]. Compared with the global and high SDI regions, the increase in ASIR and ASPR in China was higher, while the decrease in ASDR and ASR of DALYs was also more pronounced [Table 1].

Additionally, the net drift of IBD incidence in China was 2.69 (95% CI: 2.49, 2.88). The drift value rose rapidly between ages 10 years and 30 years, and then declined after age 60 [Figure 2A]. This suggests an increased risk of IBD incidence across all age groups, particularly among middle-aged individuals aged 30–60 years. The incidence rate also increased with age, peaking around 75 years old [Figure 2B]. Compared with 2005, the relative risk of IBD incidence sharply increased until it began to decline after 2015 [Figure 2C]. Compared with 1962, the relative risk of IBD incidence gradually increased over the subsequent years [Figure 2D].

Figure 2.

Figure 2

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Results of APCM for incidence of IBD in China: The local drifts (A), age effect (B), period effect (C), and birth cohort effect (D) of APCM for incidence of IBD in China. APCM: Age-Period-Cohort model; IBD: Inflammatory bowel disease; RR: Relative risk.

The net drift of IBD mortality in China was −3.23 (95% CI: −3.57, 2.88). The mortality risk increased with age until 30 but remained below zero [Figure 3A]. After age 65, the mortality risk rose rapidly, indicating a significant disease burden among the elderly [Figure 3B]. Compared with 2005, the recent IBD mortality rate in China showed a significant annual decline [Figure 3C]. Concurrently, the mortality risk of IBD also decreased annually with the progression of time [Figure 3D].

Figure 3.

Figure 3

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Results of APCM for death of IBD in China: The local drifts (A), age effect (B), period effect (C), and birth cohort effect (D) of APCM for death of IBD in China. APCM: Age-Period-Cohort model; IBD: Inflammatory bowel disease; RR: Relative risk.

The ASIR for both females and males showed a significant increasing trend between 1990 and 2021 (AAPC: 2.19 and 2.09, respectively, both P <0.05, Supplementary Table 1, http://links.lww.com/CM9/C199, Figure 4A). The ASPR also increased significantly from 1990 to 2021 (AAPC for males: 1.68, AAPC for females: 1.65, both P <0.05, Supplementary Table 1, http://links.lww.com/CM9/C199, Figure 4). The burden of death and DALYs significantly decreased regardless of sex [Supplementary Table 1, http://links.lww.com/CM9/C199, Figure 4]. Additionally, from 2015 to 2019, the ASIR and ASPR of IBD decreased [Supplementary Table 1, Supplementary Figures 1A–C, 2A–C, http://links.lww.com/CM9/C199]. Except for an increase in ASDR of IBD in China from 1998 to 2004, the overall trend was a decline [Supplementary Table 1, Supplementary Figure 1D–F, http://links.lww.com/CM9/C199]. For DALYs, the burden had significantly decreased annually since the late 1990s, with a slight increase observed in males between 1998 and 2004 [Supplementary Table 1, Supplementary Figure 2D–F, http://links.lww.com/CM9/C199].

Figure 4.

Figure 4

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Trends from 1990 to 2021 in number and ASRs of incidence, deaths, prevalence, and DALYs of IBD by sex in China. Trends from 1990 to 2021 in number and ASRs of incidence (A), deaths (B), prevalence (C), and DALYs (D) of IBD by sex in China. 95% UI: 95% uncertainty interval; ASDR: Age-standardized death rate; ASIR: Age-standardized incident rate; ASPR: Age-standardized prevalent rate; ASR: Age-standardized rate; DALYs: Disability-adjusted life years; IBD: Inflammatory bowel disease.

Prediction for incidence and death of IBD in China

By 2035, the incident cases in China are expected to reach 41,901 (male: 19,749, female: 22,152), and dead cases is projected to be 6568 (male: 2746, female: 3822). The ASIR and ASDR are expected to be 2.20 and 0.15 per 100,000 population, respectively. From 1990 to 2035, it is predicted that the ASIR for both males and females will significantly increase annually [Figure 5A, Supplementary Figure 3A, B, http://links.lww.com/CM9/C199]. By contrast, the ASDR is expected to decrease annually [Figure 5B, Supplementary Figure 3C, D, http://links.lww.com/CM9/C199]. Between 1990 and 2035, the AAPC of ASIR for male is 1.77, and for female, it is 1.89 (both P <0.05, Supplementary Table 2, http://links.lww.com/CM9/C199). For ASDR, the AAPC values for males and females are −1.92 and −2.38, respectively (both P <0.05, Supplementary Table 2, http://links.lww.com/CM9/C199). The ASIR for both males and females show a decline between 2015 and 2019, followed by a slow annual increase [Supplementary Table 2, Supplementary Figure 4A, B, http://links.lww.com/CM9/C199]. The ASDR show an overall decreasing trend [Supplementary Table 2, Supplementary Figure 4C, D, http://links.lww.com/CM9/C199].

Figure 5.

Figure 5

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Predictions for total incidence cases, death cases, ASIR and ASDR of IBD to 2035 in China by BAPC. Predictions for total incidence cases, ASIR (A), death cases, and ASDR (B) of IBD to 2035 by BAPC. ASDR: Age-standardized death rate; ASIR: Age-standardized incident rate; BAPC: Bayesian age-period-cohort; IBD: Inflammatory bowel disease.

Discussion

Although incidence and prevalence in China was lower than the global and high SDI regions, the increase in incidence and prevalence from 1990 to 2021 is among the highest in the world. Meanwhile, the ASDR and ASR of DALYs have significantly decreased. The risk of incidence among middle-aged adults in China was continuously increasing. The elderly population faced a severe mortality burden, leading to poorer quality of life. It is estimated that by 2035, the incident cases in China will reach 41,901, with 6568 deaths. During this period, the ASIR of IBD in China will continue to rise, while the ASDR will continue to decline.

China is currently still in a low prevalence area for IBD, but it is increasing rapidly. The first case of IBD in China was discovered in 1956, and there are now over 260,000 cases.[24] In just three short years from 2013 to 2016, the ASIR of IBD in China increased by approximately twofold.[25] Rapid urbanization and changes in dietary habits had led to a sharp rise in the incidence of IBD in China.[11] Over the past 30 years, large-scale migration from rural areas to megacities had resulted in each megacity in China having a population of over 10 million.[26] Residents of these large cities have been influenced by westernized societies, including increased intake of fats and refined sugars, and lifestyle changes such as increased smoking, reduced breastfeeding, and greater exposure to antibiotics.[27] These factors collectively contributed to the rising incidence of IBD in China. Additionally, China’s large population base and the increasingly severe aging problem also contribute to the rising burden of IBD.[28] Studies have found that the ASIR of IBD in urban areas of China is now comparable to that of high-income regions worldwide.[29] With improved awareness of the disease among clinicians and health practitioners, and advancements in medical technology, IBD patients are able to access diagnostic tests more easily, leading to a rapid increase in incidence and prevalence. A 20-year longitudinal study found that the diagnostic interval for IBD in China had shown a declining trend, with the diagnostic time for ulcerative colitis and Crohn’s disease patients reduced to one-ninth and one-tenth of the original time, respectively.[30] Adhering to a healthy and good lifestyle can help reduce the risk of developing IBD, even among those with a high genetic risk.[31]

While the ASIR and ASPR of IBD in China were rapidly increasing, the ASDR and DALYs were declining year by year. This was related to the emergence of new therapies, the improvement of disease management systems, and reforms in healthcare policies. Before 2006, the treatment of IBD in China was often limited to conventional therapies such as glucocorticoids, 5-aminosalicylic acid, and immunosuppressants. With the introduction of infliximab in 2006, the use of biologics in IBD treatment had gradually become more common. Biologics had also been included in the National Reimbursement Drug List, increasing the possibility for the broader IBD population to access new drugs.[5] The past two decades have undoubtedly been the “biologic era” for IBD, with a significant increase in the proportion of ulcerative colitis and Crohn’s disease patients treated with biologics.[32,33] Meanwhile, during the thirty years from 1985 to 2014, the in-hospital mortality rate of IBD patients in China also showed a significant decline.[34] The continuous decline in mortality rates may also be due to the improvement of cancer monitoring systems and better surgical techniques.[10] Interestingly, we observed a significant decline in the ASIR of IBD in China from 2015 to 2019, while the ASDR increased from 1998 to 2004. The decline in ASIR during this period may be due to the economic development and improvement of medical services, leading to the discovery of a large number of previously undiagnosed IBD patients, known as the “Unmasking of Incidence”.[35] We speculate that the 1997 Asian financial crisis, the rare major floods in China in 1998, and the significant SARS epidemic in 2003 may have caused the temporary rise in ASDR, as the historical changes in ASDR of IBD are consistent with the trend of all-cause mortality.

The changes in the age pattern of IBD incidence in China are consistent with previously observed trends. A Nationwide Employee Study found that the risk of ulcerative colitis was particularly high in the 50–59 age group, while the peak incidence age of CD varied by sex and time, gradually increasing over time.[25] The increase in early-onset IBD in the past has led to this IBD population facing a longer disease course, with more complex diseases in middle and old age, thus increasing the risk of comorbidities and treatment-related adverse events.[36] Elderly populations often have complex chronic diseases and tumors, and patients with late-onset IBD also experience more frequent comorbidities, related medications, and hospital treatments, with higher surgery and mortality rates.[5,37,38] Compared with Western countries, IBD patients in China had a higher risk of developing colon and rectal cancer.[5] The accelerating aging population in China is raising the incidence of IBD among middle-aged and elderly people, posing a more severe disease burden on the elderly.[39] More research should focus on the management and treatment of the elderly IBD population and the late-onset IBD population in China.

It is expected that between now and 2035, the ASIR of IBD in China will continue to rise, while the ASDR will continue to decline. The expected decline in mortality risk may be related to better medical resources, improved treatment plans, healthy public health measures, and advances in medical technology.[40] The continuous increase in the expected incidence risk further suggests that IBD in China will be in the acceleration in incidence stage and gradually transition to compounding prevalence.[35]

Due to data limitations, we were unable to separately analyze the disease burden of ulcerative colitis and Crohn’s disease, as well as the burden differences across various regions in China. At the same time, GBD 2021 currently does not provide data on risk factors for IBD, such as poverty, antibiotic use, sleep, diet, and so on, or other indicators for assessing disease burden such as cost, length of hospitalization, and quality of life. China accounts for about 18.3% of the world’s population, with extensive geographical, dietary, cultural, ethnic, and economic differences, significantly affecting the burden of IBD. Apart from the aforementioned factors, we were also unable to assess the impact of health policies and medical technologies on the short-term trends of future IBD burden changes. Moreover, it is undeniable that the data from the GBD may differ from other databases and the real world, which to some extent affects the accuracy of the estimates.[41] We compared the differences between nationwide real-world IBD burden studies and GBD estimates, discovering that the burden estimated by GBD was lower. This discrepancy may be due to inaccuracies in GBD estimates or because the study only represents urban working and retired employees, potentially leading to an overestimation.[25] Lastly, China currently lacks reliable large-scale IBD research centers and monitoring systems, which provides relatively limited data sources for the GBD 2021, thereby affecting the reliability of its estimates.

In conclusion, China faced an increasingly aggravating burden of IBD, posing significant challenges to the middle-aged and elderly populations. Establishing and improving the disease management system will help provide better medical support for the broad IBD population.

Funding

This study was supported by grants from the Capital Health Research and Development of Special Foundation (No. 2022-2-4014), National Key Clinical Specialty Construction Project (No. ZK108000), National High-Level Hospital Clinical Research Funding (Nos. 2022-PUMCH-B-022, 2022-PUMCH-C-018, 2022-PUMCH-A-074, and 2022-PUMCH-A-179), National Natural Science Foundation of China (No. 81970495), CAMS Innovation Fund for Medical Sciences (No. 2022-I2M-C&T-B-011), National Key R&D Program of China (No. 2023YFC2507300, 2023YFC2507302), State Key Laboratory Special Fund (No. 2060204), and Undergraduate Training Program on Innovation and Entrepreneurship (No. 2024dcxm091).

Conflicts of interest

None.

Supplementary Material

SUPPLEMENTARY MATERIAL
cm9-137-2851-s001.pdf (1.4MB, pdf)

Footnotes

Ziqing Yu and Gechong Ruan contributed equally to this work.

How to cite this article: Yu ZQ, Ruan GC, Bai XY, Sun YH, Yang H, Qian JM. Growing burden of inflammatory bowel disease in China: Findings from the Global Burden of Disease Study 2021 and predictions to 2035. Chin Med J 2024;137:2851–2859. doi: 10.1097/CM9.0000000000003345

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