Comorbid immune-mediated diseases in inflammatory bowel disease: a nation-wide population-based study

The two-directional prospective association between inflammatory bowel disease and neurodegenerative disorders: a systematic review and meta-analysis based on longitudinal studies

Objective

Previous studies reported possible connections between inflammatory bowel disease (IBD) and several neurodegenerative disorders. However, the comprehensive relationships between IBD and various neurodegenerative disorders were not summarized. We executed a meta-analysis of longitudinal studies to provide an estimate of the strength of the two-directional prospective association between IBD and neurodegenerative disorders.

Methods

We accomplished a thorough bibliographic search of PubMed, Web of Science, Embase, PsycINFO, and Cochrane Library databases until June 2023 to locate relevant longitudinal studies. The extracted data were then analyzed via meta-analysis using either a fixed or random effects model.

Results

The final analysis encompassed 27 studies. Individuals with IBD faced an increased risk of developing four neurodegenerative disorders than the general public, namely, Alzheimer's disease (hazard ratio[HR] = 1.35, 95% confidence interval [CI]: 1.03-1.77, P=0.031), dementia (HR =1.24, 95% CI: 1.13-1.36, P<0.001), multiple sclerosis (HR =2.07, 95% CI:1.42-3.02, P<0.001) and Parkinson's disease (HR =1.23, 95% CI:1.10-1.38, P<0.001). Two articles reported an increased incidence of amyotrophic lateral sclerosis or multiple system atrophy in IBD patients. Three studies investigated the prospective association between multiple sclerosis and IBD, revealing an elevated risk of the latter in patients with the former. (HR=1.87, 95% CI:1.66-2.10, P<0.001).

Interpretation

These findings verified the two-directional relationship between the brain-gut axis, specifically demonstrating a heightened risk of various neurodegenerative diseases among IBD patients. It may be profitable to prepare screening strategies for IBD patients to find neurodegenerative diseases during the long-term course of treatment for IBD with a view to potential earlier diagnosis and treatment of neurodegenerative diseases, reducing public health and social burden.

Systematic Review Registration

PROSPERO (CRD42023437553).

Prevalence of Hepatobiliary Manifestations in Inflammatory Bowel Disease: A GRADE Assessed Systematic Review and Meta-Analysis of more than 1.7 Million Patients

BACKGROUND AND AIMS

Inflammatory bowel disease [IBD] comprises an immune-mediated group of chronic gastrointestinal disorders. Patients with IBD may experience extraintestinal manifestations, such as hepatobiliary complications. This meta-analysis aims to assess the prevalence of different hepatic manifestations in IBD patients.

METHODS

For this systematic review and meta-analysis, PubMed, Scopus, Web of Science, and Embase were searched until July 20, 2022, by specifying keywords for IBD, hepatic manifestations, and study type. Full texts of cohort studies in English that examined the prevalence of different hepatic manifestations were included in this study. The primary outcome was the overall prevalence of hepatic manifestations in IBD patients. For the statistical analysis, a proportion by random effect model meta-analysis was performed. The registration number for the protocol of this study in PROSPERO is CRD42022369595.

RESULTS

From the 4421 articles retrieved from the primary search, 118 met the inclusion criteria and were included in the final analysis. After a pooled analysis of 1 729 128 patients, the overall prevalence of hepatic manifestations was 3.49% (95% confidence interval [CI]: 3.31-3.68%; I2: 99.55%). The pooled prevalence of non-alcoholic fatty liver disease in 228 216 patients was 26.1% [95% CI: 22.1-30.2%; I2: 99.018%]. After pooled analysis of 9642 patients, the prevalence of primary sclerosing cholangitis was 1.67% [95% CI: 1.47-1.88%; I2: 99.10%]. The pooled prevalence of biliary stones was 4.1% [95% CI: 3.6-4.7%; I2: 97.43%]. Autoimmune hepatitis (0.51% [95% CI: 0.26-0.75%]; I2: 85.36%) and portal vein thrombosis (0.21% [95% CI: 0.08-0.33%]; I2: 97.95%) are considered as rare manifestations.

CONCLUSION

This study summarizes the prevalence and importance of different hepatic manifestations in IBD patients. These findings are crucial for the management of extraintestinal manifestations, especially hepatic manifestations, in IBD patients.

Potential role of SNP rs2071475 in rheumatoid arthritis and inflammatory bowel disease in the East Asian population: a Mendelian randomization study

BACKGROUND

Previous observational studies have identified an association between rheumatoid arthritis (RA) and inflammatory bowel disease (IBD). However, the causal relationship between RA and IBD in the East Asian population remains uncertain.

METHODS

The two-sample Mendelian randomization (MR) analysis was conducted to elucidate the potential causal relationship between RA and IBD. Summary-level data from genome-wide association studies (GWAS) in the East Asian population were utilized, including RA (n = 19,190) and IBD (n = 6543), including Crohn's disease (CD, n = 5409) and ulcerative colitis (UC, n = 4853). The inverse variance weighted (IVW) method was employed as the primary analysis, supplemented by weighted median, weighted mode, simple median, MR-Egger, and MR-PRESSO analyses. Sensitivity analyses were conducted to assess the robustness of the results. Genetic data for RA (n = 22,515) were utilized to validate the findings in the East Asian population.

RESULTS

The IVW method showed no significant association between genetically predicted RA and overall IBD in the East Asian population (OR = 1.028; 95% CI: 0.935-1.129; P = 0.567). The subgroup analysis revealed a positive association between RA and CD (OR = 1.268; 95% CI: 1.108-1.451; P < 0.001), while a negative association was observed with UC (OR = 0.839; 95% CI: 0.710-0.993; P = 0.041). These findings were supported by another set of RA data. Additionally, an SNP rs2071475 was identified to play an important role in CD and UC.

CONCLUSION

This study revealed a potential increased susceptibility to CD and a decreased susceptibility to UC in the East Asian population with RA. Furthermore, a key SNP rs2071475 was discovered along with its opposite effects in CD and UC. These findings provide new evidence for research on the corresponding molecular mechanisms and offer insights for clinical management of RA-associated IBD.

Risk of Common Neurological Disorders in Adult Patients with Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

BACKGROUND

Several studies investigated the risks of neurological conditions in patients with inflammatory bowel disease (IBD), with some variability in findings. We aimed to perform a systematic review and meta-analysis of available evidence to elucidate the association between IBD and the risks of common neurological disorders.

METHODS

We conducted a literature search through Embase, PubMed, Scopus, and ProQuest databases from inception to June 30, 2023, to identify cohort studies assessing the risk of developing stroke, all-cause dementia, Parkinson's disease (PD), multiple sclerosis (MS), seizure/epilepsy, and peripheral neuropathy in adult IBD patients compared with non-IBD population. We combined hazard ratios (HRs) with 95% confidence intervals (CIs) to compute pooled estimates using a random-effects model.

RESULTS

In total, 22 cohort studies were included, of which 9 studies reported 7074 stroke events in 202 460 IBD patients, 5 studies reported 3783 all-cause dementia diagnoses in 109 602 IBD patients, 7 studies reported 932 PD diagnoses in 354 792 IBD patients, and 1 study reported 6 MS events in 35 581 IBD patients. We observed increased risks of incident stroke (pooled HR = 1.19; 95% CI, 1.06-1.31), all-cause dementia (pooled HR = 1.22; 95% CI, 1.05-1.38), PD (pooled HR = 1.39; 95% CI, 1.20-1.58), and MS (HR = 2.89; 95% CI, 1.02-8.42). No eligible studies were found on peripheral neuropathy and seizure/epilepsy.

CONCLUSIONS

Inflammatory bowel disease may be modestly associated with increased risks of stroke, all-cause dementia, and PD. Further longitudinal studies are warranted to investigate potential links with MS, seizure/epilepsy, and peripheral neuropathy, as well as their clinical significance.

Cytokines in Spondyloarthritis and Inflammatory Bowel Diseases: From Pathogenesis to Therapeutic Implications

Spondyloarthritis and inflammatory bowel diseases are chronic immune disorders of the joints and the gut that often coexist in the same patient, increasing the burden of each disorder, worsening patients' quality of life, and influencing therapeutic strategies. Genetic predisposition, environmental triggers, microbiome features, immune cell trafficking, and soluble factors such as cytokines contribute to the pathogenesis of both articular and intestinal inflammation. Most of the molecular targeted biological therapies developed over the last two decades were based on evidence that specific cytokines may be involved in these immune diseases. Despite pro-inflammatory cytokine pathways sharing the pathogenesis of both articular and gut diseases (i.e., tumor necrosis factor and interleukin-23), several other cytokines (i.e., interleukin-17) may be differently involved in the tissue damage process, depending on the specific disease and the organ involved in inflammation, making difficult the identification of a therapeutic plan that is efficacious for both inflammatory manifestations. In this narrative review, we comprehensively summarize the current knowledge on cytokine involvement in spondyloarthritis and inflammatory bowel diseases, underlining similarities and differences among their pathogenetic pathways; finally, we provide an overview of current and potential future treatment strategies to simultaneously target both articular and gut immune disorders.

Health Care Use and Barriers to Care for Chronic Inflammatory Diseases (CID) among First and Second Generation South Asian Immigrant Children and Parents in Ontario Canada

Although immigrants are disproportionately impacted by growing chronic inflammatory disease (CIDs) rates, yet suffer barriers to access health care, little attention has been given to their primary healthcare or specialist healthcare access as it relates to complex, chronic diseases in Canada, a country with universal health care. This study aims to investigate CID health care use and barriers to care among first- and second-generation immigrant South Asian children and parents in the Greater Toronto Area, Ontario. Drawing on analysis of 24 in depth interviews with children and parents (14 children, 10 parents), the results reveal that although CIDs disproportionately affects South Asian immigrants, they encounter health system, geographic, interpersonal, and knowledge barriers to access requisite care. These barriers exist despite participants having a GP, and are compounded further by limited familial systems, culturally insensitive care, and structural inequities that in some instances make parents choose between health access or other basic needs. Although all participants recognized the importance of specialized care, only 11 participants regularly accessed specialized care, creating new schisms in CID management. The findings suggest that a multisectoral approach that address individual and structural level socio-structural drivers of health inequities are needed to create more equitable healthcare access.

Research hotspot and trend analysis in the diagnosis of inflammatory bowel disease: A machine learning bibliometric analysis from 2012 to 2021

Aims

This study aimed to conduct a bibliometric analysis of the relevant literature on the diagnosis of inflammatory bowel disease (IBD), and show its current status, hot spots, and development trends.

Methods

The literature on IBD diagnosis was acquired from the Science Citation Index Expanded of the Web of Science Core Collection. Co-occurrence and cooperation relationship analysis of authors, institutions, countries, journals, references, and keywords in the literature were carried out through CiteSpace software and the Online Analysis platform of Literature Metrology. At the same time, the relevant knowledge maps were drawn, and the keywords cluster analysis and emergence analysis were performed.

Results

14,742 related articles were included, showing that the number of articles in this field has increased in recent years. The results showed that PEYRIN-BIROULET L from the University Hospital of Nancy-Brabois was the author with the most cumulative number of articles. The institution with the most articles was Mayo Clin, and the United States was far ahead in the article output and had a dominant role. Keywords analysis showed that there was a total of 818 keywords, which were mainly focused on the research of related diseases caused or coexisted by IBD, such as colorectal cancer and autoimmune diseases, and the diagnosis and treatment methods of IBD. Emerging analysis showed that future research hotspots and trends might be the treatment of IBD and precision medicine.

Conclusion

This research was the first bibliometric analysis of publications in the field of IBD diagnosis using visualization software and data information mining, and obtained the current status, hotspots, and development of this field. The future research hotspot might be the precision medicine of IBD, and the mechanism needed to be explored in depth to provide a theoretical basis for its clinical application.

Impact of the COVID‐19 pandemic on inflammatory bowel disease: The role of emotional stress and social isolation

Inflammatory bowel disease (IBD) is a chronic health condition exacerbated by negative emotional stress experiences. In the current study, we examined whether the outbreak of the COVID-19 pandemic coincided with an increase in stress experiences and accordingly an aggravation of disease activity in IBD patients. Sixty-three IBD patients (30 Crohn's disease or CD, 33 ulcerative colitis) completed an online survey during the COVID-19-related lockdown, assessing clinical disease activity, disease-related quality of life, presence of functional gastrointestinal symptoms, social isolation and stress experiences. Scores were then compared to pre-lockdown baseline screening. The pandemic yielded a significant baseline-to-lockdown increase in emotional stress and social isolation. Stress increments, particularly those occasioned by interpersonal tension and excessive interpersonal proximity, were associated with a worsening of functional gastrointestinal symptoms. Exacerbations of loneliness coincided with an escalation of CD activity, functional gastrointestinal symptoms and a decline in subjective health. Lastly, COVID-19 anxiety was significantly related to CD symptom severity and social dysfunction. The findings show that shifts in IBD expression are closely linked to changes in emotional stress experiences and interpersonal relatedness. As such, they contribute to a better understanding of inter-individual differences in IBD progression and provide leads for therapeutic interventions.

Plasma miRNA Profile of Crohn's Disease and Rheumatoid Arthritis Patients

Crohn's disease (CD) and rheumatoid arthritis (RA) are immune mediated inflammatory diseases. Several studies indicate a role for microRNAs (miRNAs) in the pathogenesis of a variety of autoimmune diseases, including CD and RA. Our study's goal was to investigate circulating miRNAs in CD and RA patients to identify potential new biomarkers for early detection and personalized therapeutic approaches for autoimmune diseases. For this study, subjects with CD (n = 7), RA (n = 8) and healthy controls (n = 7) were recruited, and plasma was collected for miRNA sequencing. Comparison of the expression patterns of miRNAs between CD and healthy patients identified 99 differentially expressed miRNAs. Out of these miRNAs, 4 were down regulated, while 95 were up regulated. Comparison of miRNAs between RA and healthy patients identified 57 differentially expressed miRNAs. Out of those, 12 were down regulated, while 45 were up regulated. For all the miRNAs down regulated in CD and RA patients, 420 GO terms for biological processes were similarly regulated between both groups. Therefore, the identification of new plasma miRNAs allows the emergence of new biomarkers that can assist in the diagnosis and treatment of CD and RA.

Polypharmacy in Patients With Inflammatory Bowel Disease: Prevalence and Outcomes in a Single-center Series

BACKGROUND

Polypharmacy can complicate the course and management of chronic diseases, and has been little explored in patients with inflammatory bowel disease (IBD) to date.

AIM

The aim of this study was to determine the prevalence of polypharmacy in a series of IBD patients, describing associated factors and its correlation with poor disease outcomes.

MATERIALS AND METHODS

Retrospective study of a single-center series. Polypharmacy was defined as the simultaneous use of 5 or more drugs. Disease outcomes, IBD treatment nonadherence and undertreatment were evaluated at 1 year.

RESULTS

A total of 407 patients were included [56% males, median age: 48 y (interquartile range, 18 to 92 y)], of whom 60.2% had Crohn's disease; Chronic comorbidity and multiple comorbidities were present in 54% and 27% of patients, respectively. Median number of prescriptions per patient was 3 (range: 0 to 15). Polypharmacy was identified in 18.4% of cases, inappropriate medication in 10.5% and use of high-risk drugs in 6.1% (mainly opioids). In multivariate analysis, polypharmacy was associated with chronic comorbidity [odds ratio (OR)=10.1, 95% confidence interval (CI): 2.14-47.56; P˂0.003], multiple comorbidities (OR=3.53, 95% CI: 1.46-8.51; P=0.005) and age above 62 years (OR=3.54, 95% CI: 1.67-7.51; P=0.001). No association with poor disease outcomes was found at 12 months. However, polypharmacy was the only factor associated with IBD treatment nonadherence (OR=2.24, 95% CI: 1.13-4.54, P=0.02).

CONCLUSIONS

Polypharmacy occurs in around 1 in 5 patients with IBD, mainly in older adults and those with comorbidity. This situation could interfere with adherence to IBD treatment and therapeutic success.

Multiple sclerosis and inflammatory bowel disease: A systematic review and meta‐analysis

Background

Multiple sclerosis (MS) and inflammatory bowel disease (IBD) are two autoimmune diseases that seriously affect patients' quality of life. Previous studies have established an association between MS and IBD, including Crohn's disease (CD) and ulcerative colitis (UC), but the results were inconsistent. The aim of this study was to quantify the prevalences of and the association between MS and IBD.

Methods

The PubMed, Web of Science, and Embase databases were searched through November 2020 for studies reporting data on MS among patients with IBD and vice versa. The main outcomes were the proportion of MS in patients with IBD and vice versa, as well as the association (risk ratio [RR]) of IBD in MS and that of MS in IBD.

Results

Based on the analysis of 17 studies, the prevalence of MS in patients with IBD was 0.2% (95% CI 0.1–0.4%), while the prevalence of IBD in patients with MS was 0.6% (95% CI 0.4–0.9%). Patients with MS had a higher prevalence of IBD than controls (RR = 1.53, 95% CI 1.38–1.70, p < 0.00001). There was a similarly high risk of developing CD (RR 1.41, 95% CI 1.14–1.74, p = 0.001) or UC (RR 1.42, 95% CI 1.17–1.71, p = 0.0003) in patients with MS (p for subgroup differences: 0.97). Patients with IBD had a higher prevalence of MS than controls (RR = 1.91, 95% CI 1.06–3.45, p = 0.03).

Conclusions

Clinicians should be aware of the increased risk of IBD or MS comorbidity during the diagnostic process. Systematic diagnosis and management at an earlier stage are suggested.

Curcumin Alleviated Dextran Sulfate Sodium-Induced Colitis by Regulating M1/M2 Macrophage Polarization and TLRs Signaling Pathway

Curcumin has shown good efficacy in mice with experimental colitis and in patients with ulcerative colitis, but the mechanism of action through the regulation of M1/M2 macrophage polarization has not been elaborated. The ulcerative colitis was modeled by dextran sulfate sodium; colitis mice were orally administrated with curcumin (10 mg/kg/day) or 5-ASA (300 mg/kg/day) for 14 consecutive days. After curcumin treatment, the body weight, colon weight and length, colonic weight index, and histopathological damage in colitis mice were effectively improved. The concentrations of proinflammatory cytokines IL-1β, IL-6, and CCL-2 in the colonic tissues of colitis mice decreased significantly, while anti-inflammatory cytokines IL-33 and IL-10 increased significantly. Importantly, macrophage activation was suppressed and M1/M2 macrophage polarization was regulated in colitis mice, and the percentage of CD11b⁺F4/80⁺ and CD11b⁺F4/80⁺TIM-1⁺ and CD11b⁺F4/80⁺iNOS⁺ decreased significantly and CD11b⁺F4/80⁺CD206⁺ and CD11b⁺F4/80⁺CD163⁺ increased significantly. Additionally, curcumin significantly downregulated CD11b⁺F4/80⁺TLR4⁺ macrophages and the protein levels of TLR2, TLR4, MyD88, NF-κBp65, p38MAPK, and AP-1 in colitis mice. Our study suggested that curcumin exerted therapeutic effects in colitis mice by regulating the balance of M1/M2 macrophage polarization and TLRs signaling pathway.

Systematic Review with Meta-analysis: The Impact of Co-occurring Immune-mediated Inflammatory Diseases on the Disease Course of Inflammatory Bowel Diseases

BACKGROUND AND AIMS

Patients with inflammatory bowel diseases (IBDs) are at risk of developing a variety of other immune-mediated inflammatory diseases (IMIDs). The influence of co-occurring IMIDs on the disease course of IBD remains unknown. The aim of this study was therefore to conduct a systematic review and meta-analysis of the impact of IMIDs on phenotypic presentation and outcome in patients with IBD.

METHODS

PubMed and Embase were searched from their earliest records through December 2018 and updated in October 2019 for studies reporting proportions or ratios of IBD-related disease outcomes in patients with and without co-occurring IMIDs. Meta-analyses were performed to estimate summary proportions and risks of the main outcomes. PRISMA guidelines were used, and study quality was assessed according to the Newcastle-Ottawa Scale.

RESULTS

A total of 93 studies were identified, comprising 16,064 IBD patients with co-occurring IMIDs and 3,451,414 IBD patients without IMIDs. Patients with IBD and co-occurring IMIDs were at increased risk of having extensive colitis or pancolitis (risk ratio, 1.38; 95% Cl, 1.25-1.52; P < 0.01, I2 = 86%) and receiving IBD-related surgeries (risk ratio, 1.17; 95% Cl, 1.01-1.36; P = 0.03; I2 = 85%) compared with patients without IMIDs. Co-occurrence of IMIDs other than primary sclerosing cholangitis in patients with IBD was associated with an increased risk of receiving immunomodulators (risk ratio, 1.15; 95% Cl, 1.06-1.24; P < 0.01; I2 = 60%) and biologic therapies (risk ratio, 1.19; 95% Cl, 1.08-1.32; P < 0.01; I2 = 53%).

CONCLUSION

This meta-analysis found that the presence of co-occurring IMIDs influences the disease course of IBD, including an increased risk of surgery and its phenotypical expression.

Impact of immune-mediated diseases in inflammatory bowel disease and implications in therapeutic approach

Inflammatory bowel diseases (IBD) belong to the group of immune-mediated diseases (IMIDs). The effect of associated IMIDs in the prognosis in IBD is nowadays unknown. To describe IMIDs associated to IBD patients and evaluate differences linked to the presence or absence of IMIDs. A unicentric retrospective descriptive study was designed. A cohort of 1,448 patients were categorized according to the presence of IMIDs. Clinical characteristics were obtained from IBD database. Univariate and multivariate analysis were performed. 385 patients were diagnosed with associated IMIDs while 1,063 had no associated IMIDs. A prevalence of 26.6% IMIDs associated to IBD was observed. Asthma, skin psoriasis and rheumatoid diseases were most commonly found. Factors associated to the presence of IMIDs were women (OR 1.48; 95 CI 1.17–1.87) and Crohn’s disease (OR 1.35; 95 CI 1.07–1.70). Patients with associated IMIDs required more immunomodulator (OR 1.61; 95 CI 1.27–2.43) and biological treatment (OR 1.81; 95 CI 1.47–2.43). More surgical risk was observed in multivariate analysis in those patients diagnosed with IMIDs prior to the onset of IBD (OR 3.71; 95% CI 2.1–6.56). We considered the presence of IMIDs a poor prognostic factor and suggest a closer monitoring of these patients.

The risk of rheumatoid arthritis among patients with inflammatory bowel disease: a systematic review and meta-analysis

Background

Studies have suggested that patients with inflammatory bowel disease (IBD) have an increased risk of rheumatoid arthritis (RA). However, the available data on this association are inconsistent. This meta-analysis aimed to determine the association between IBD and the risk of RA.

Methods

Observational studies investigating the RA risk among patients with IBD (Crohn disease (CD) and/or ulcerative colitis (UC)) were searched in PubMed, Embase, and Web of Science from the date of inception to December 2019. The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale. Relative risks (RRs) and corresponding 95% confidential intervals (CIs) were pooled with a random-effects model. Heterogeneity was evaluated using I² statistics while publication bias was determined using Begg’s and Egger’s tests. Subgroup and sensitivity analyses were performed.

Results

A total of three cohort studies, three cross-sectional studies, and two case-control studies were included in the meta-analyses. Compared to the non-IBD control or general population, there was a significantly higher risk of RA among patients with IBD (RR = 2.59; 95% CI: 1.93–3.48). Moreover, both CD (RR = 3.14; 95% CI: 2.46–4.01) and UC (RR = 2.29; 95% CI: 1.76–2.97) were associated with a significantly increased risk of RA. However, heterogeneity was substantial across studies and the subgroup analyses failed to identify the potential source of heterogeneity.

Conclusions

Patients with IBD have a greater risk of developing RA. Rheumatologists should be consulted when patients with IBD present with undifferentiated joint complaints. However, more prospective cohort studies are needed to validate these results.

Viewpoint: Inflammatory Bowel Diseases Among Immigrants From Low- to High-Incidence Countries: Opportunities and Considerations

The inflammatory bowel diseases [IBDs], inclusive of Crohn's disease [CD] and ulcerative colitis [UC], are chronic, progressive immune-mediated diseases associated with high morbidity and substantial economic impact. The pathogenesis implicates a complex interaction between environmental determinants and genetic susceptibility. Of concern, the incidence and prevalence of IBD are increasing globally, with the highest relative increase observed in developing and recently developed countries. One high-risk yet underappreciated population is immigrants from countries of low to high IBD incidence, as evidenced by epidemiologic studies demonstrating higher risk of IBD among second- versus first-generation and younger versus older immigrants from low- to high-incidence countries [LTHICs]. The reasons underlying these emerging patterns among immigrants are incompletely understood and provide enormous opportunities to better define the pathophysiology of IBD and move toward disease prevention or at least earlier diagnosis. The rapidity of this epidemiologic shift in the demographic profile of IBD, which was traditionally a disease of Caucasians in industrialized countries, strongly implicates non-genetic factors and gene-environment interactions in the pathophysiology of IBD among immigrants from LTHICs. The primary objectives of this Viewpoint are to [1] provide a focused overview of IBD epidemiology among immigrants from countries at differential IBD risk; [2] emphasize the potential to advance our understanding of IBD pathogenesis via targeted research efforts to delineate risk and protective determinants in this cohort; and [3] highlight disparities and barriers in IBD care, as well as the economic implications of the rising, yet underappreciated, disease burden among immigrants from LTHICs.

Changing epidemiology of immune-mediated inflammatory diseases in immigrants: A systematic review of population-based studies

BACKGROUND

Immune-mediated inflammatory diseases (IMIDs) are systemic diseases of multifactorial etiology that share aberrant immune responses as the common final pathway. With rising globalization, their incidence is increasing in developing countries and among immigrants. Our primary objective was to systematically review the epidemiology of IMIDs in immigrants and conduct a meta-analysis to estimate the risk of IMIDs in immigrant populations according to their origin and destination countries.

METHODS

We systematically searched five biomedical databases and reviewed population-based studies, from inception through August 2018, that reported incidence or prevalence data of inflammatory bowel disease (IBD), multiple sclerosis (MS), type 1 diabetes (T1D), systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), ankylosing spondylitis (AS) or psoriasis and psoriatic arthritis (PPA) among immigrants and the host population.

RESULTS

The incidence and prevalence of IMIDs among immigrants differ from host populations, and evolve over subsequent generations. The risk of IBD among immigrants approximates that in hosts, especially among South Asians, with ulcerative colitis incidence changing prior to Crohn's disease incidence. MS risk is highest in Iranian immigrants, T1D in African immigrants and SLE in African and Iraqi immigrants. Data on other IMIDs are sparse. Significant heterogeneity between the studies precluded meta-analysis.

CONCLUSION

Based on our systematic review, the epidemiology of IMIDs among immigrants varies according to native and host countries, immigrant generation, and IMID type. The rapid evolution suggests a role for non-genetic factors and gene-environment interactions. Future studies should focus on these pattern shifts, given implications of rising global burden of IMIDs and immigration.