Fine-scale geographic variations of inflammatory bowel disease in France: correlation with socioeconomic and house equipment variables

Leveraging Administrative Health Databases to Address Health Challenges in Farming Populations: Scoping Review and Bibliometric Analysis (1975-2024)

BACKGROUND

Although agricultural health has gained importance, to date, much of the existing research relies on traditional epidemiological approaches that often face limitations related to sample size, geographic scope, temporal coverage, and the range of health events examined. To address these challenges, a complementary approach involves leveraging and reusing data beyond its original purpose. Administrative health databases (AHDs) are increasingly reused in population-based research and digital public health, especially for populations such as farmers, who face distinct environmental risks.

OBJECTIVE

We aimed to explore the reuse of AHDs in addressing health issues within farming populations by summarizing the current landscape of AHD-based research and identifying key areas of interest, research gaps, and unmet needs.

METHODS

We conducted a scoping review and bibliometric analysis using PubMed and Web of Science. Building upon previous reviews of AHD-based public health research, we conducted a comprehensive literature search using 72 terms related to the farming population and AHDs. To identify research hot spots, directions, and gaps, we used keyword frequency, co-occurrence, and thematic mapping. We also explored the bibliometric profile of the farming exposome by mapping keyword co-occurrences between environmental factors and health outcomes.

RESULTS

Between 1975 and April 2024, 296 publications across 118 journals, predominantly from high-income countries, were identified. Nearly one-third of these publications were associated with well-established cohorts, such as Agriculture and Cancer and Agricultural Health Study. The most frequently used AHDs included disease registers (158/296, 53.4%), electronic health records (124/296, 41.9%), insurance claims (106/296, 35.8%), population registers (95/296, 32.1%), and hospital discharge databases (41/296, 13.9%). Fifty (16.9%) of 296 studies involved >1 million participants. Although a broad range of exposure proxies were used, most studies (254/296, 85.8%) relied on broad proxies, which failed to capture the specifics of farming tasks. Research on the farming exposome remains underexplored, with a predominant focus on the specific external exposome, particularly pesticide exposure. A limited range of health events have been examined, primarily cancer, mortality, and injuries.

CONCLUSIONS

The increasing use of AHDs holds major potential to advance public health research within farming populations. However, substantial research gaps persist, particularly in low-income regions and among underrepresented farming subgroups, such as women, children, and contingent workers. Emerging issues, including exposure to per- and polyfluoroalkyl substances, biological agents, microbiome, microplastics, and climate change, warrant further research. Major gaps also persist in understanding various health conditions, including cardiovascular, reproductive, ocular, sleep-related, age-related, and autoimmune diseases. Addressing these overlooked areas is essential for comprehending the health risks faced by farming communities and guiding public health policies. Within this context, promoting AHD-based research, in conjunction with other digital data sources (eg, mobile health, social health data, and wearables) and artificial intelligence approaches, represents a promising avenue for future exploration.

Farming Activities and Risk of Inflammatory Bowel Disease: A French Nationwide Population-based Cohort Study

BACKGROUND AND AIMS

Epidemiological data regarding inflammatory bowel disease [IBD] are lacking, in particular for occupationally exposed populations. We investigated whether, among the entire French farm manager [FM] workforce, certain agricultural activities are more strongly associated with IBD than others.

METHODS

Nationwide, population-based, insurance claims and electronic health records from all FMs who worked at least once over the period 2002-2016 were used [n = 1 088 561, 69% males]. The outcome measure was the association between 26 farming activities and the risk of IBD, Crohn's disease [CD], and ulcerative colitis [UC], measured as hazard ratios [HRs], after adjusting for age, sex, pre-existing medical comorbidities, and farm location. The time to first chronic disease declaration was used as the underlying time scale. A model was generated for every activity and disease, using a reference group comprising all FMs who abstained from the specified activity from 2002 to 2016.

RESULTS

There were 1752 IBD cases, with 704 CD [40.2%] and 1048 UC [59.8%] cases, respectively. Elevated HRs were observed for fruit arboriculture [HR from 1.17 to 1.52] and dairy farming [HR from 1.22 to 1.46] for all IBD, in crop farming for CD only (HR = 1.26, 95% confidence interval [CI]: 1.06-1.49), and in shellfish farming [HR from 2.12 to 2.51] for both CD and IBD.

CONCLUSIONS

Further research regarding specific farming activities and exposures likely to modify the microbiota [eg, pesticides, pathogens] is required to identify potential occupational risk factors [agricultural exposome] for IBD. Exposure to Mycobacterium avium subspecies paratuberculosis, Cryptosporidium, environmental toxins, micro/nanoplastics, and pesticides represents promising research avenues.

Inflammatory bowel disease later diagnosed as strongyloides colitis in migrants to Canada: a case series

Strongyloides colitis is a gastrointestinal manifestation of the parasitic infection, Strongyloides stercoralis, which may be misdiagnosed and treated as ulcerative colitis (UC) in patients presenting in non-endemic regions. Treatment of Strongyloides colitis as UC can lead to a lethal hyperinfection syndrome. Therefore, prior to commencing immunosuppressive treatment of UC, it is essential to use diagnostic markers to differentiate the two etiologies. In this case series, we discuss two migrant patients who were previously diagnosed with UC and treated accordingly who presented to our clinic for further investigation of suspected parasitic infection.

Environmental variables and genome-environment interactions predicting IBD diagnosis in large UK cohort

A combination of genetic susceptibility and environmental exposure is thought to cause inflammatory bowel disease (IBD), but the non-genetic component remains poorly characterized. We therefore undertook a search for environmental variables and gene-environment interactions associated with future IBD diagnosis in a large UK cohort. Using self-report and electronic health records, we identified 1946 Crohn's disease (CD) and 3715 ulcerative colitis (UC) patients after quality control in the UK Biobank. Based on prior literature and biological plausibility , we tested 38 candidate environmental variables for association with CD, UC, and overall IBD using Cox proportional hazard regressions. We also tested whether these variables interacted with polygenic risk in predicting disease, following up significant (FDR < 0.05) results with tests for SNP-environment associations. We performed robustness analyses on all significant results. As in previous reports, appendectomy protected against UC, smoking (both current and previous) elevated risk for CD, current smoking protected against UC, and previous smoking imparted a risk for UC. Childhood antibiotic use associated with IBD, as did sun exposure during the winter. Socioeconomic deprivation was conferred a risk for IBD, CD, and UC. We uncovered negative interactions between polygenic risk and previous oral contraceptive use for IBD and UC. Polygenic risk also interacted negatively with previous smoking in predicting UC. There were no individually significant SNP-environment interactions. Thus, for a limited set of environmental variables, there was strong evidence of association with IBD diagnosis in the UK Biobank, and interaction with polygenic risk was minimal.

Effects of ethnicity and socioeconomic status on surgical outcomes from inflammatory bowel disease

PURPOSE

Evidence suggests that ethnicity and socioeconomic status of patients with chronic diseases influence their healthcare outcomes. The aim of this study was to assess the impact of these factors on the surgical outcome of patients with inflammatory bowel disease (IBD) over a 15-year period.

METHODS

A retrospective observational study investigated IBD patients operated on at an NHS Trust between 2000-2015, with follow-up data until 2020. Logistic regression models were used to determine the relationship between ethnic minority background and Index of Multiple Deprivation (IMD) on outcomes including requirement for intra-abdominal surgery, permanent stoma, re-do surgery and surgical complications, accounting for age, gender, smoking history and biologic treatment.

RESULTS

There were 1,620 patients (56.7% ulcerative colitis (UC) and 43.3% Crohn's disease (CD)). Median age was 32 years, and 49.6% were female. Patients with an ethnic minority background accounted for 20.6%. Within 5 years of first presentation, 369 patients required intra-abdominal surgery, 95 permanent stomas and 107 re-do surgery. For CD patients, younger age at diagnosis, female patients, those with an ethnic minority background, higher IMD quintile, smoking history and biologic treatment were more likely to have intra-abdominal surgery. Ethnic minority background and higher IMD score were further associated with surgical complications for CD but not UC patients.

CONCLUSION

Ethnic minority status and socioeconomic deprivation were associated with worse surgical outcomes within our cohort of IBD patients. These findings may stimulate discourse regarding the strategic planning of equitable healthcare services.

The role of vitamin D in inflammatory bowel disease: a guide for clinical practice

INTRODUCTION

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract that carries significant morbidity and mortality. Given the need to identify modifiable risk factors to prevent IBD development and to mitigate disease severity, vitamin D has become a major candidate of interest.

AREAS COVERED

In this review, we discuss the regulatory role played by vitamin D in intestinal immune homeostasis, updates in the recent literature exploring its role in de novo IBD pathogenesis and established IBD activity. We also discuss societal recommendations on its therapeutic role in maintaining bone health and future directions for studying its role in regulating disease activity.

EXPERT OPINION

In contrast to findings from earlier studies suggesting a causal role in IBD, recent findings indicate that vitamin D deficiency may be a sequela rather than a cause of IBD. Additionally, clinical trials exploring vitamin D therapy in reducing disease activity remain inconclusive thus far, with the current evidence best supporting a therapeutic role of vitamin D in bone health. Future studies are needed to clarify the role of vitamin D in IBD development and disease activity and to determine its therapeutic potential for IBD disease activity.

Environmental, Nutritional, and Socioeconomic Determinants of IBD Incidence: A Global Ecological Study

BACKGROUND AND AIMS

The wide variation in inflammatory bowel disease [IBD] incidence across countries entails an opportunity to recognise global disease determinants and hypothesise preventive policies.

METHODS

We fitted multivariable models to identify putative environmental, nutritional, and socioeconomic determinants associated with the incidence of IBD (i.e. ulcerative colitis [UC] and Crohn's disease [CD]). We used the latest available country-specific incidence rates, and aggregate data for 20 determinants, from over 50 countries accounting for more than half of the global population. We presented the associations with exponentiated beta coefficients (exp[β]) indicating the relative increase of disease incidence per unit increase in the predictor variables.

RESULTS

Country-specific incidence estimates demonstrate wide variability across the world, with a median of 4.8 new UC cases (interquartile range [IQR] 2.4-9.3), and 3.5 new CD cases [IQR 0.8-5.7] per 100 000 population per year. Latitude (exp[β] 1.05, 95% confidence interval [CI] 1.04‒1.06, per degree increase), prevalence of obesity [1.05, 1.02‒1.07, per 1% increase], and of tobacco smoking [0.97, 0.95‒0.99, per 1% increase] explained 71.5% of UC incidence variation across countries in the adjusted analysis. The model for CD included latitude [1.04, 1.02‒1.06], expenditure for health (1.03, 1.01‒1.05, per 100 purchasing power parity [PPP]/year per capita increase), and physical inactivity prevalence [1.03, 1.00‒1.06, per 1% increase], explaining 58.3% of incidence variation across countries. Besides expenditure for health, these associations were consistent in low/middle- and high-income countries.

CONCLUSIONS

Our analysis highlights factors able to explain a substantial portion of incidence variation across countries. Further high-quality research is warranted to develop global strategies for IBD prevention.

Fine-scale geographical distribution and ecological risk factors for Crohn's disease in France (2007-2014)

BACKGROUND

Geographical variations in Crohn's disease (CD) suggest that the environment has a role in the pathogenesis of this condition.

AIMS

To describe the spatial distribution and the clustering of CD cases in France, and to assess the relationship between the prevalence of CD and environmental risk factors.

METHODS

We identified all patients with CD included in the French hospital discharge database from 2007 to 2014. Age- and gender-smoothed standardised prevalence ratios over this period were computed for 5610 spatial units. An ecological regression analysis was used to assess the relationship between the risk of CD and ecological variables (health care, latitude, socio-economic deprivation, urbanisation, proportion of agricultural surfaces and density of industries). Local spatial clusters of high-CD prevalence were searched for using elliptic spatial scan statistics and characterised in a hierarchical ascendant classification based on the same ecological variables.

RESULTS

About 129 089 patients with CD were identified, yielding a crude prevalence of 203 per 100 000 inhabitants. The overall spatial heterogeneity was statistically significant (P < .001). An elevated risk of CD was found to be significantly associated with high-social deprivation (relative risk [95% confidence interval] = 1.05 [1.02-1.08]) and high urbanisation (1.09 [1.04-1.14]). Sixteen significant spatial clusters of high-CD prevalence were identified; there were no common ecological variables.

CONCLUSIONS

The geographical distribution of CD prevalence in France is not uniform, and is associated with high levels of social deprivation and urbanisation. Larger ecological databases integrating more detailed environmental and clinical information are needed.

Urban-rural environmental exposure during childhood and subsequent risk of inflammatory bowel disease: a meta-analysis

BACKGROUND

The relationship between living conditions in urban and rural areas during childhood and subsequent inflammatory bowel disease (IBD) remains controversial.

AIM

To explore the association between environmental exposures early in life and the subsequent risk of IBD.

METHODS

Literature searches were conducted in the following databases: PubMed, EMBASE, and Conference Proceedings Citation Index. Studies were analyzed separately using rate ratios (RRs) or odds ratios (ORs) with 95% confidence intervals.

RESULTS

The search strategy identified 15 studies. Of these, 9 studies explored the association between urban exposure during childhood and ulcerative colitis (UC), and 12 and 4 studies explored this relationship with Crohn's disease (CD) and IBD, respectively. A meta-analysis showed that the pooled ORs estimated for the case-control studies of UC, CD, and IBD were 1.16 (0.83, 1.61), 1.45 (1.45, 1.85), and 1.34 (1.11, 1.62), respectively. The pooled RR estimated for the cohort studies of CD and IBD was 1.48 (1.17, 1.87). The stratified analysis and meta-regression showed significant relationships between CD and living conditions in case-control studies published during 2010-2017 and in non-European countries (P < 0.05).

CONCLUSIONS

Living conditions during childhood are positively associated with the subsequent development of IBD. Urban living environment is more common among those with CD than UC.

Population Density and Risk of Inflammatory Bowel Disease: A Prospective Population-Based Study in 13 Countries or Regions in Asia-Pacific

INTRODUCTION

Living in an urban environment may increase the risk of developing inflammatory bowel disease (IBD). It is unclear if this observation is seen globally. We conducted a population-based study to assess the relationship between urbanization and incidence of IBD in the Asia-Pacific region.

METHODS

Newly diagnosed IBD cases between 2011 and 2013 from 13 countries or regions in Asia-Pacific were included. Incidence was calculated with 95% confidence interval (CI) and pooled using random-effects model. Meta-regression analysis was used to assess incidence rates and their association with population density, latitude, and longitude.

RESULTS

We identified 1175 ulcerative colitis (UC), 656 Crohn's disease (CD), and 37 IBD undetermined (IBD-U). Mean annual IBD incidence per 100 000 was 1.50 (95% CI: 1.43-1.57). India (9.31; 95% CI: 8.38-10.31) and China (3.64; 95% CI, 2.97-4.42) had the highest IBD incidence in Asia. Incidence of overall IBD (incidence rate ratio [IRR]: 2.19; 95% CI: 1.01-4.76]) and CD (IRR: 3.28; 95% CI: 1.83-9.12) was higher across 19 areas of Asia with a higher population density. In China, incidence of IBD (IRR: 2.37; 95% CI: 1.10-5.16) and UC (IRR: 2.63; 95% CI: 1.2-5.8) was positively associated with gross domestic product. A south-to-north disease gradient (IRR: 0.94; 95% CI: 0.91-0.98) was observed for IBD incidence and a west-to-east gradient (IRR: 1.14; 95% CI: 1.05-1.24) was observed for CD incidence in China. This study received IRB approval.

CONCLUSIONS

Regions in Asia with a high population density had a higher CD and UC incidence. Coastal areas within China had higher IBD incidence. With increasing urbanization and a shift from rural areas to cities, disease incidence may continue to climb in Asia.

Vitamin D Status and Its Relation to Inflammatory Markers in Patients with Mild to Moderate Ulcerative Colitis

BACKGROUND

Inflammatory bowel disease (IBD), Crohn’s disease (CD), and Ulcerative colitis (UC) are autoimmune inflammatory diseases of the alimentary tract, which seems to be caused by the interaction of environmental and genetic factors as well as diet and nutritional factors such as vitamin D. The aim of this study was to assess the vitamin D status and its associations with erythrocyte sedimentation rate (ESR), and high-sensitivity C-reactive protein (hs-CRP) as inflammatory markers in patients with UC.

METHODS

In this analytical cross-sectional study 90 patients with mild to moderate UC who were resident of Tehran were assessed. 25(OH)D, parathyroid hormone (PTH), ESR and hs-CRP were measured. Dietary intake was assessed by 3-day 24h diet recall. Statistical analyses were performed using STATA (Version 12).

RESULTS

The average serum 25-OH-vitamin D3 was 33.1 ± 8.3 ng/mL and 38.9% of the patients were vitamin D deficient or insufficient (37.3% of men and 41% of women). No significant correlation between serum 25(OH)D and hs-CRP, ESR, body mass index (BMI), and disease duration was found. There were no significant differences in serum 25(OH)D between men and women. Mean daily dietary vitamin D and calcium intakes were 189.5 Iu (95% CI: 176.0 - 203.1) and 569.5 mg (95% CI: 538.8 - 600.2) respectively.

CONCLUSION

In this cross-sectional study 38.9% of the patients with mild to moderate UC were vitamin D deficient or insufficient and vitamin D level was not correlated to ESR and/or hs-CRP. More studies are needed to investigate the effect of vitamin D in the pathogenesis of UC or as a part of its treatment.

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

BACKGROUND

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

METHODS

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

FINDINGS

We identified 147 studies that were eligible for final inclusion in the systematic review, including 119 studies of incidence and 69 studies of prevalence. The highest reported prevalence values were in Europe (ulcerative colitis 505 per 100 000 in Norway; Crohn's disease 322 per 100 000 in Germany) and North America (ulcerative colitis 286 per 100 000 in the USA; Crohn's disease 319 per 100 000 in Canada). The prevalence of inflammatory bowel disease exceeded 0·3% in North America, Oceania, and many countries in Europe. Overall, 16 (72·7%) of 22 studies on Crohn's disease and 15 (83·3%) of 18 studies on ulcerative colitis reported stable or decreasing incidence of inflammatory bowel disease in North America and Europe. Since 1990, incidence has been rising in newly industrialised countries in Africa, Asia, and South America, including Brazil (APC for Crohn's disease +11·1% [95% CI 4·8-17·8] and APC for ulcerative colitis +14·9% [10·4-19·6]) and Taiwan (APC for Crohn's disease +4·0% [1·0-7·1] and APC for ulcerative colitis +4·8% [1·8-8·0]).

INTERPRETATION

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

FUNDING

None.

Solar radiation is inversely associated with inflammatory bowel disease admissions

OBJECTIVE

To explore the associations between latitude and solar radiation with inflammatory bowel disease admission rates in Chile, the country with the largest variation in solar radiation in the world.

PATIENTS AND METHODS

This is an ecological study, which included data on all hospital-admitted population for inflammatory bowel disease between 2001 and 2012, according to different latitudes and solar radiation exposures in Chile. The data were acquired from the national hospital discharge database from the Department of Health Statistics and Information of the Chilean Ministry of Health.

RESULTS

Between 2001 and 2012 there were 12,869 admissions due to inflammatory bowel disease (69% ulcerative colitis, 31% Crohn's disease). Median age was 36 years (IQR: 25-51); 57% were female. The national inflammatory bowel disease admission rate was 6.52 (95% CI: 6.40-6.63) per 100,000 inhabitants with increasing rates over the 12-year period. In terms of latitude, the highest admission rates for pediatric ulcerative colitis and Crohn's disease, as well as adult ulcerative colitis, were observed in the southernmost region with lowest annual solar radiation. Linear regression analysis showed that regional solar radiation was inversely associated with inflammatory bowel disease admissions in Chile (β: -.44, p = .03).

CONCLUSIONS

Regional solar radiation was inversely associated with inflammatory bowel disease admission rates in Chile; inflammatory bowel disease admissions were highest in the southernmost region with lowest solar radiation. Our results support the potential role of vitamin D deficiency on inflammatory bowel disease flares.

Literature review: impacts of socioeconomic status on the risk of inflammatory bowel disease and its outcomes

The relationship between socioeconomic status (SES) and inflammatory bowel disease (IBD) is controversial. To date, research has focused on effects on incidence and prevalence, disease management and clinical outcomes; however, conclusions remain uncertain. This review examines current evidence, identifies what remains to be understood and explores the practical implications this has for today. A structured literature search in Ovid, Medline, the Cochrane library, Google Scholar and clinicaltrials.gov was performed using defined key words, including all articles up until 5 October 2016 assessing SES as a primary or secondary outcome measure. Twenty-one studies were identified, investigating incidence and prevalence (n=13), disease outcomes (n=5) and mortality (n=3). Data linking SES with IBD incidence are conflicting, with studies citing both positive and negative trends. Patients with low SES, particularly those with Crohn's disease, show higher rates of hospitalization, service usage and IBD-associated mortality. On the basis of the available study data, it is difficult to relate SES with the risk of IBD. For Crohn's disease, in particular, the link between deprivation and increased hospitalization and mortality observed from world-wide studies is alarming. It seems most likely that the cause links to well-documented behavioural, materialistic, psychosocial and life-course models used to explain social class inequalities in other diseases.

Assessment of corticosteroid-related quality of care measures for ulcerative colitis and Crohn's disease in the United States: a claims data analysis

OBJECTIVE

To evaluate corticosteroid (CS)-related quality of care indicators in patients with ulcerative colitis (UC) and Crohn's disease (CD) in the US.

METHODS

Adults diagnosed with UC or CD and prescription fills for an oral CS were identified from a large commercial US claims database (2005-2013). Quality indicators included prolonged CS use (≥60 days), use of CS-sparing therapy, and bone loss assessment. State-level variations in quality of care indicators were estimated using logistic regression models adjusting for age, gender, insurance plan type, and CD severity.

RESULTS

Of the 25,063 UC and 22,155 CD patients receiving CS, 16.1% and 12.6%, respectively, were prolonged CS users. Among prolonged CS users, 52.5% of UC and 68.2% of CD patients used CS-sparing therapy. Bone loss assessment was observed in 11.0% of UC patients with prolonged CS use and 7.7% of newly diagnosed CD patients. Prolonged CS use was the lowest in Kentucky (odds ratio [OR] = 0.59) and the highest in Wisconsin (OR = 1.41) for UC patients; the lowest in North Carolina and New York (both OR = 0.71) and the highest in Utah (OR = 2.42) for CD patients. CS-sparing therapy use was the lowest in Delaware (OR = 0.42) and the highest in Michigan (OR = 0.83) for UC patients; it was significantly different only in South Carolina (OR = 0.57) for CD patients. Bone loss assessment rates were the highest in Arizona (OR = 1.83) for UC patients and were the lowest in Mississippi (OR = 0.52) and the highest in Texas (OR = 1.51) for CD patients.

LIMITATIONS

Information on disease severity was not available in the database.

CONCLUSIONS

Significant regional variations in all three quality indicators were observed across the US.

Role of Vitamin D in Inflammatory Bowel Disease

Vitamin D is a secosteroid hormone that possesses immunomodulatory properties and has been demonstrated to potentially influence inflammatory bowel disease (IBD) pathogenesis and activity. Epidemiologic data have associated vitamin D deficiency with an increased risk of IBD, hospitalizations, surgery, and loss of response to biologic therapy. Conversely, IBD itself can lead to vitamin D deficiency. This bidirectional relationship between vitamin D and IBD suggests the need for monitoring and repletion of vitamin D, as needed, in the IBD patient. This review discusses the role of vitamin D in IBD and provides practical guidance on vitamin D repletion.

Vitamin D and the Pathogenesis of Inflammatory Bowel Disease

Vitamin D has traditionally been known for its role in bone metabolism, but emerging evidence has suggested a broader role for vitamin D in immune regulation. Vitamin D deficiency has been associated with the pathogenesis of diverse autoimmune disorders and has similarly been implicated as a contributor to inflammatory bowel disease. In this review, we discuss animal, in vitro, genetic, and epidemiologic studies that have linked vitamin D deficiency with inflammatory bowel disease pathogenesis or severity. Nonetheless, we present the caveat in interpreting these studies in the context of reverse causation: Does vitamin D deficiency lead to gastrointestinal disease, or does gastrointestinal disease (with related changes in dietary choices, intestinal absorption, nutritional status, lifestyle) lead to vitamin D deficiency?

Northern Latitude but Not Season Is Associated with Increased Rates of Hospitalizations Related to Inflammatory Bowel Disease: Results of a Multi-Year Analysis of a National Cohort

Background and Aims

There is growing evidence that the incidence and severity of inflammatory bowel disease (IBD) may be geographically and seasonally related. Why these associations are observed remains unclear. We assessed the impact of geographic location, season, and exposure to ultraviolet light on disease severity by measuring national hospital IBD-related discharge rates.

Methods

Utilizing the Nationwide Inpatient Sample (NIS), we identified all patients with IBD-related discharges from 2001–2007. Patients were included if they were discharged from states above the 40^th parallel (north) or at or below the 35^th parallel (south); and their discharge fell within the winter (January, February, and March) or summer (July, August, and September). Groups of patients were assessed comparing north to south within each season, and summer to winter within each region. UV index was recorded from the National Weather Service data and compared to monthly discharge rates.

Results

There was a consistent pattern of increased IBD-related hospitalization rates in northern states compared to southern states for both ulcerative colitis and Crohn’s disease. Differences in IBD-related hospitalization rates by season, however, were not uniform across the years studied. UV index was significantly inversely associated although not proportional to discharge rates for both Crohn’s disease and ulcerative colitis.

Conclusions

In the US, there is a significant increased rate of IBD-related hospitalizations in the northern compared to southern states, which not fully explained by differences in UV exposure.

Environmental risk factors for inflammatory bowel diseases: Evidence based literature review

AIM: Advances in genetics and immunology have contributed to the current understanding of the pathogenesis of inflammatory bowel diseases (IBD).

METHODS: The current opinion on the pathogenesis of IBD suggests that genetically susceptible individuals develop intolerance to dysregulated gut microflora (dysbiosis) and chronic inflammation develops as a result of environmental insults. Environmental exposures are innumerable with varying effects during the life course of individuals with IBD. Studying the relationship between environmental factors and IBD may provide the missing link to increasing our understanding of the etiology and increased incidence of IBD in recent years with implications for prevention, diagnosis, and treatment. Environmental factors are heterogeneous and genetic predisposition, immune dysregulation, or dysbiosis do not lead to the development of IBD in isolation.

RESULTS: Current challenges in the study of environmental factors and IBD are how to effectively translate promising results from experimental studies to humans in order to develop models that incorporate the complex interactions between the environment, genetics, immunology, and gut microbiota, and limited high quality interventional studies assessing the effect of modifying environmental factors on the natural history and patient outcomes in IBD.

CONCLUSION: This article critically reviews the current evidence on environmental risk factors for IBD and proposes directions for future research.

Vitamin D deficiency in patients with intestinal malabsorption syndromes--think in and outside the gut

There is a very high prevalence of vitamin D deficiency, which is defined by a serum level of 25-hydroxyvitamin D [25(OH)D] of lower than 20 ng/mL, in all populations of the world. Unfortunately, the prevalence of vitamin D deficiency in patients with intestinal malabsorption syndromes, including cystic fibrosis (CF), celiac disease (CD), short bowel syndrome and inflammatory bowel disease (IBD), is higher than that in the general population, indicating the presence of disease-specific causative factors. In this review, we aimed to present clinical findings to highlight the roles of insufficient exposure to sunlight and inflammation in the development of vitamin D deficiency in patients with intestinal malabsorption syndromes. Furthermore, we aimed to present experimental evidence that supported a role of vitamin D deficiency in the pathogenesis of IBD. Finally, we reviewed clinical intervention strategies aiming to normalize vitamin D status in and even to improve the conditions of patients and to discuss certain issues that needed to be addressed in future research.

Variation in incidence of pediatric Crohn's disease in relation to latitude and ambient ultraviolet radiation: a systematic review and analysis

BACKGROUND

Pediatric Crohn's disease (CD) is a lifelong, debilitating, and costly disease. In previous studies, CD incidence increased with higher geographic latitude in the Northern Hemisphere. This may indicate a role for lower vitamin D status as a risk factor for CD. Analysis of worldwide incidence of pediatric CD has not been previously reported.

METHODS

We undertook a systematic review of population-based studies reporting incidence of pediatric CD and published between 2003 and 2013. Included studies had well-defined diagnostic criteria for CD, evidence of high case ascertainment, reported incidence according to age group, and provided a specific location. Average daily ambient ultraviolet radiation (UVR) for each location was derived from satellite data. Negative binomial regression was used to assess the association between pediatric CD incidence and latitude and ambient UVR, adjusting for the study year.

RESULTS

Twenty-eight articles provided 39 incidence data points. Incidence of pediatric CD increased with higher latitude, and in association with a greater number of months where the average daily UVR was lower than a previously published threshold of 1.488 kJ/m. Incidence of pediatric CD increased over calendar time.

CONCLUSIONS

After applying rigorous quality assessment criteria, and including only population-based studies, there was a modest increase in incidence of pediatric CD with higher latitude and greater number of months with low ambient UVR. Reporting using nonconsistent diagnostic criteria and age groups, with poorly defined geographic locations, makes it difficult to compare data across different studies.

Environment and the inflammatory bowel diseases

Inflammatory bowel diseases (IBD), which consists of Crohn disease and ulcerative colitis, are chronic inflammatory conditions of the gastrointestinal tract. In genetically susceptible individuals, the interaction between environmental factors and normal intestinal commensal flora is believed to lead to an inappropriate immune response that results in chronic inflammation. The incidence of IBD have increased in the past century in developed and developing countries. The purpose of the present review is to summarize the current knowledge of the association between environmental risk factors and IBD. A number of environmental risk factors were investigated including smoking, hygiene, microorganisms, oral contraceptives, antibiotics, diet, breastfeeding, geographical factors, pollution and stress. Inconsistent findings among the studies highlight the complex pathogenesis of IBD. Additional studies are necessary to identify and elucidate the role of environmental factors in IBD etiology.

Latitude, sunshine, and human lactase phenotype distributions may contribute to geographic patterns of modern disease: the inflammatory bowel disease model

Countries with high lactase nonpersistence (LNP) or low lactase persistence (LP) populations have lower rates of some "western" diseases, mimicking the effects of sunshine and latitude. Inflammatory bowel disease (IBD), ie, Crohn's disease and ulcerative colitis, is putatively also influenced by sunshine. Recent availability of worldwide IBD rates and lactase distributions allows more extensive comparisons. The aim of this study was to evaluate the extent to which modern day lactase distributions interact with latitude, sunshine exposure, and IBD rates. National IBD rates, national distributions of LP/LNP, and population-weighted average national annual ultraviolet B exposure were obtained, estimated, or calculated from the literature. Negative binomial analysis was used to assess the relationship between the three parameters and IBD rates. Analyses for 55 countries were grouped in three geographic domains, ie, global, Europe, and non-Europe. In Europe, both latitude and ultraviolet B exposure correlate well with LP/LNP and IBD. In non-Europe, latitude and ultraviolet B exposure correlate weakly with LP/LNP, but the latter retains a more robust correlation with IBD. In univariate analysis, latitude, ultraviolet B exposure, and LP/LNP all had significant relationships with IBD. Multivariate analysis showed that lactase distributions provided the best model of fit for IBD. The model of IBD reveals the evolutionary effects of the human lactase divide, and suggests that latitude, ultraviolet B exposure, and LP/LNP mimic each other because LP/LNP follows latitudinal directions toward the equator. However, on a large scale, lactase patterns also follow lateral polarity. The effects of LP/LNP in disease are likely to involve complex interactions.

Isotretinoin and risk of inflammatory bowel disease: a French nationwide study

OBJECTIVES

Isotretinoin, a drug widely prescribed for severe acne, has been suspected to increase the risk of ulcerative colitis (UC), but data are conflicting. To further examine the association between isotretinoin use and risk for UC and Crohn's disease (CD), we conducted a large nationwide case-control study in France.

METHODS

We used information from the National Health Insurance system for all French people covered by the general scheme between 1 January 2008 and 31 December 2010, totaling over 50 million individuals (i.e., 76% of the whole French population). All incident claims for UC and CD and all medical drug reimbursements were automatically recorded in the database. For each case, four controls were matched on age, gender, year of enrollment, and follow-up duration. The association between isotretinoin use and UC or CD claim was estimated by conditional logistic regression.

RESULTS

We included 7,593 cases of inflammatory bowel disease (IBD; 3,187 UC, 4,397 CD, and 9 indeterminate colitis) and 30,372 controls; among them, 26 cases (0.3%) (15 UC (0.5%) and 11 CD (0.3%)) and 140 controls (0.4%) were exposed to isotretinoin. Isotretinoin exposure was not associated with an increased risk for UC (odds ratio (OR)=1.36 (95% confidence intervals (CI): 0.76, 2.45)) but was associated with a decreased risk for CD (OR=0.45 (95% CI: 0.24, 0.85)), P value for homogeneity between UC and CD=0.001. Results were similar in analyses restricted to individuals below the age of 40 years, to cases with colonoscopy or intestinal surgery, or when adjusting for other acne treatments.

CONCLUSIONS

In this population-based case-control study, isotretinoin use was not associated with increased UC risk but was associated with a decreased CD risk. This study provides reassuring data for people using isotretinoin.

Linking vitamin d deficiency to inflammatory bowel disease

Inflammatory bowel disease is associated with industrialization, and its incidence has increased markedly over time. The prospect of reversing these trends motivates the search for the agent(s) involved. Modernity entails several physical and behavioral modifications that compromise both the photosynthesis of cholecalciferol in the skin and of its bioavailability. Although deficiency in this "vitamin" has therefore emerged as a leading candidate, and despite the publication of a randomized control trial that showed a trend toward statistically significant benefit in Crohn's disease, its causal agency has yet to be demonstrated by an adequately powered study. We discuss the strengths and weaknesses of the case being made by epidemiologists, geneticists, clinicians, and basic researchers, and consolidate their findings into a model that provides mechanistic plausibility to the claim. Specifically, converging data sets suggest that local activation of vitamin D coordinates the activity of the innate and adaptive arms of immunity, and of the intestinal epithelium, in a manner that promotes barrier integrity, facilitates the clearance of translocated flora, and diverts CD4 T cell development away from inflammatory phenotypes. Because smoking is an important risk-altering exposure, we also discuss its newly established melanizing effect and other emerging evidence linking tobacco use to immune function through vitamin D pathways.

High and increasing prevalence of inflammatory bowel disease in Finland with a clear North-South difference

BACKGROUND AND AIM

Inflammatory bowel disease (IBD) prevalence has increased and a North-South gradient has been reported. We estimated the nationwide prevalence of IBD, ulcerative colitis (UC) and Crohn's disease (CD) in 1993, and prevalence of IBD in 2008, and assessed the geographical distribution of IBD in Finland. In addition, we investigated the vitamin D levels in a study population from a large, nationally representative health examination survey, the Health 2000 Survey.

METHODS

The register study for prevalences included all patients who had special reimbursement of medications for IBD in the years 1993 (n=10,958) and 2008 (31,703). The study for D-vitamin measurement consisted of 6134 persons who had participated in the Health 2000 Survey.

RESULTS

The nationwide point prevalence of IBD in 1993 was 216 per 100,000 inhabitants, and 595 in 2008. In 1993, the prevalence of UC (177) was fourfold higher than the prevalence of CD (38). The prevalence of IBD and UC in Finland increased from South to North. For CD, no geographical variation could be demonstrated. In the Health 2000 survey, vitamin D levels were lower in Northern than in Southern Finland.

CONCLUSIONS

Finland belongs to high prevalence area of IBD and this prevalence has increased nearly threefold during the past 15 years. A clear North-South gradient has been shown for IBD and UC, but not for CD. Slightly lower vitamin D levels in Northern Finland may be associated with the observed higher prevalence of IBD there.

Can temperature explain the latitudinal gradient of ulcerative colitis? Cohort of Norway

Background

Incidence and prevalence of ulcerative colitis follow a north–south (latitudinal) gradient and increases northwards at the northern hemisphere or southwards at the southern hemisphere. The disease has increased during the last decades. The temporal trend has been explained by the hygiene hypothesis, but few parallel explanations exist for the spatial variability. Many factors are linked to latitude such as climate. Our purpose was to investigate the association between variables governing the climate and prospectively identified patients.

Methods

In this study, we used a subset of the population-based Cohort of Norway (n = 80412) where 370 prevalent cases of ulcerative colitis were identified through self-reported medication. The meteorological and climatic variables temperature, precipitation, and altitude were recorded from weather stations of the Norwegian Meteorological Institute. Summer temperature was used to capture environmental temperature.

Results

Summer temperature was significantly related to the prevalence of ulcerative colitis. For each one-degree increase in temperature the odds for ulcerative colitis decreased with about 9% (95% CI: 3%-15%). None of the other climatic factors were significantly associated to the risk of ulcerative colitis. Contextual variables did not change the association to the prevalence of ulcerative colitis.

Conclusions

The present results show that the prevalence of ulcerative colitis is associated to summer temperature. Our speculation is that summer temperature works as an instrumental variable for the effect of microbial species richness on the development of ulcerative colitis. Environmental temperature is one of the main forces governing microbial species richness and the microbial composition of the commensal gut flora is known to be an important part in the process leading to ulcerative colitis.

Environmental triggers for inflammatory bowel disease

Inflammatory bowel diseases [IBD; Crohn's disease (CD), ulcerative colitis (UC)] are chronic immunologically mediated diseases that are due to a dysregulated immune response to intestinal flora in a genetically susceptible host. Despite advances in genetics, the likelihood of occurrence of disease remains incompletely explained and there appears to be a strong role for the environment in mediating risk of disease. Smoking remains the most widely studied and replicated risk factor, contributing to increased risk and severity of CD while conferring protection against UC. Recent data has suggested novel risk factors. Lower plasma vitamin D is associated with an increased risk of Crohn's disease, and vitamin D supplementation may prevent relapse of disease. Several medications including oral contraceptives, post-menopausal hormone replacement, aspirin, NSAIDs, and antibiotics may increase risk of CD or UC with the mechanisms of effect remaining inadequately defined. There is continuing evidence that depression and psychosocial stress may play a role in the pathogenesis of both CD and UC, while at the same time also increasing risk for disease flares. There is also a growing understanding of the role of diet on IBD, in particular through its effect on the microbiome. Animal protein intake and n-6 fatty acids may increase risk of UC while n-3 fatty acids and dietary fiber may confer protection. The effect of diet on established disease remains poorly studied. There is need for routine measurement of a spectrum of environmental exposures in prospective studies to further our understanding.

Prevalence of esophageal eosinophilia varies by climate zone in the United States

OBJECTIVES

The epidemiology of eosinophilic esophagitis (EoE) is rapidly evolving, and differences in climate could impact the prevalence of EoE. We aimed to examine the association between esophageal eosinophilia and climate zones in the United States.

METHODS

This was a cross-sectional study of esophageal biopsies from 2008 to 2010 in a large US pathology database. Cases were patients with esophageal eosinophilia; controls had normal esophageal biopsies. A Köppen-Geiger (K-G) climate class was assigned to each patient, and the association between case-control status and the main K-G climate type (tropical, arid, temperate, or cold) was assessed.

RESULTS

A total of 233,649 patients were included, 71,948 (30.8%) with normal esophageal biopsies and 9,995 (4.3%) with esophageal eosinophilia. Using the temperate zone as the referent and after multivariable analysis, the odds of esophageal eosinophilia were highest in the cold climate zone (odds ratio (OR)=1.39, 95% confidence interval (CI): 1.34-1.47), compared with the tropical zone (OR=0.87; 95% CI: 0.71-10.8) and the arid zone (OR=1.27; 95% CI: 1.19-1.36). Increased likelihood of EoE was also associated with increasing odds of being in the cold climate zone. Compared with patients with normal esophageal biopsies, patients with dysphagia, a clinical suspicion of EoE, no reflux or Barrett's esophagus, esophageal eosinophilia, and eosinophilic microabscesses had the highest adjusted odds of being in a cold climate zone (OR 2.02; 1.78-2.28).

CONCLUSIONS

Esophageal eosinophilia differs significantly between K-G climate zones, with the highest prevalence in the cold and arid zones. Geographical and climate patterns may help identify candidate antigens characteristic to high-prevalence areas to be targeted for future investigation.

Solar radiation and vitamin D: mitigating environmental factors in autoimmune disease

This paper looks at the environmental role of vitamin D and solar radiation as risk reduction factors in autoimmune disease. Five diseases are considered: multiple sclerosis, type 1 diabetes, rheumatoid arthritis, autoimmune disease of the thyroid, and inflammatory bowel disease. Clinical relevant studies and factors that may indicate evidence that autoimmune disease is a vitamin D-sensitive disease are presented. Studies that have resulted in prevention or amelioration of some autoimmune disease are discussed. An example of the utility of supplementing vitamin D in an unusual autoimmune disease, idiopathic thrombocytic purpura, is presented.

Environmental factors in inflammatory bowel disease: a case-control study based on a Danish inception cohort

BACKGROUND

The role of environmental factors in development of inflammatory bowel disease (IBD) remains uncertain. The aim of the present study was to assess a number of formerly suggested environmental factors in a case-control study of an unselected and recently diagnosed group of patients with IBD and a control group of orthopaedic patients.

METHODS

A total of 123 patients diagnosed with Crohn's disease (CD) and 144 with ulcerative colitis (UC) in Copenhagen (2003-2004) were matched 1:1 on age and gender to 267 orthopaedic controls. Participants received a questionnaire with 87 questions concerning environmental factors prior to IBD/orthopaedic admission. Odds ratios (OR) were calculated by logistic regression.

RESULTS

Being breastfed >6 months (OR, 0.50; 95% CI, 0.23-1.11) and undergoing tonsillectomy (OR, 0.49; 95% CI, 0.31-0.78) decreased the odds for IBD, whereas appendectomy decreased the odds for UC only (OR, 0.29; 95% CI, 0.12-0.71). Vaccination against pertussis (OR, 2.08; 95% CI, 1.07-4.03) and polio (OR, 2.38; 95% CI, 1.04-5.43) increased the odds for IBD, whereas measles infection increased the odds for UC (OR, 3.50; 95% CI, 1.15-10.6). Low consumption of fibres and high consumption of sugar were significantly associated with development of CD and UC. Smoking increased the risk for CD and protected against UC.

CONCLUSION

Among Danish patients with CD and UC belonging to an unselected cohort, disease occurrence was found to be associated both with well-known factors such as smoking and appendectomy, and with more debated factors including breastfeeding, tonsillectomy, childhood vaccinations, childhood infections, and dietary intake of fibres and sugar.

Modeling geographic risk of complex congenital heart defects in Eastern Wisconsin

BACKGROUND

Geographic variation may be an indicator of risk factors for birth defects. This study models the geographic distribution of three complex congenital heart defects (CHDs) in eastern Wisconsin, and evaluates effects of demographic census variables linked to geographic location.

METHODS

Cases of Hypoplastic Left Heart Syndrome (HLHS), Tetralogy of Fallot (TOF) and d-Transposition of the Great Arteries (d-TGAs) born between1995 and 2004 were identified from three medical centers serving eastern Wisconsin. Case diagnoses were assigned by a pediatric cardiologist using echocardiographic records. Births by ZIP code were obtained from the State of Wisconsin. ZIP Code demographic variables were derived from 2000 census data. Numbers of cardiac defects by ZIP code were modeled using cluster analysis and Poisson generalized additive models (GAMs) for spatial coordinates including all and white only cases (excluding trisomies). GAM analyses were repeated adjusting for census variables.

RESULTS

Four hundred forty-eight cases were ascertained. A significant south-to-north spatial gradient for HLHS, TOF, and combined CHDs, but not d-TGAs was identified. This gradient remained significant when census variables were included in the model for the full sample. In the analysis excluding non-white cases, findings were the same for TOF, combined CHDs, and d-TGAs. However, the geographic gradient for HLHS was not significant in the adjusted model.

CONCLUSIONS

A south-to-north gradient was apparent for two of three complex CHDs in eastern Wisconsin. For white cases, demographic variation seems to explain some of this spatial gradient in HLHS. Further studies are needed to confirm demographic and other risk factors underlying this geographic gradient.

Ambient air pollution correlates with hospitalizations for inflammatory bowel disease: an ecologic analysis

BACKGROUND

Known genetic loci account for less than 25% of the risk for inflammatory bowel disease (IBD), suggesting a potential role for environmental triggers. The association between ambient air pollution and IBD hospitalizations has not been previously studied.

METHODS

Data from the Wisconsin Hospital Association (WHA) for the year 2002 was used to identify the number of IBD-related hospitalizations for each of the 72 counties in Wisconsin. Average annual emissions density (2002) for each of the six criteria pollutants were obtained for each county from the Environmental Protection Agency. Pearson correlation and Poisson regression analysis were performed at the level of the county.

RESULTS

There was a mean of 81.3 IBD hospitalizations/100,000 population per county (range 0-174). The total criteria pollutant emissions density correlated significantly with adult IBD hospitalizations (Pearson's correlation coefficient (rho) 0.28, P = 0.02). On Poisson regression, a 1-log increase in the density of total criteria pollutant emission was associated with a 40% increase in the rate of IBD hospitalizations (incidence rate ratio [IRR] 1.40, 95% confidence interval [CI] 1.31-1.50) This was similar for both ulcerative colitis (UC) (IRR 1.48, 95% CI 1.27-1.73) and Crohn's disease (CD) hospitalizations (IRR 1.39, 95% CI 1.26-1.52). Analysis of each of the individual criteria pollutant emission densities revealed a significant association for all the component criteria pollutants.

CONCLUSIONS

In this ecologic analysis, total air emissions of criteria pollutants appear to be associated with hospitalizations for IBD in adults. The ecologic design precludes drawing firm conclusions about association or causality and further research is needed.

Low exposure to sunlight is a risk factor for Crohn's disease

BACKGROUND

Low sunshine exposure might contribute to the pathogenesis of inflammatory bowel disease (IBD).

AIM

To assess the geographic distribution of IBD incidence in relation to sunshine exposure in France to test the hypothesis that higher sun exposure is associated with lower IBD risk.

METHODS

Using the national health insurance database, incidence rates of Crohn's disease (CD) and ulcerative colitis (UC) were estimated for each of the 94 French administrative areas ('départements'), between 2000 and 2002. The surface UV radiation intensity was obtained by combining modelling and satellite data from Meteosat, the European meteorological satellite. Relationships between incidence rates and sun exposure were tested for significance by using a Poisson regression. We mapped smoothed relative risks (sRR) for CD and UC, using a Bayesian approach and adjusting for sun exposure, to search for geographical variations.

RESULTS

Areas with a smoothed RR of CD incidence significantly above 1 corresponded to areas with low sunshine exposure, whereas those with high or medium sunlight exposure had smoothed RRs either lower than 1 or not significantly different from 1. There was no association between sun exposure and UC incidence.

CONCLUSIONS

This geographic study suggests that low sunlight exposure is associated with an increased incidence of Crohn's disease. Further studies are needed to determine if this association is causal.

French national health insurance information system and the permanent beneficiaries sample

In France, in the early 2000s, legislators ordered that the National Health Insurance regime develop an inter-regime information system (SNIIR-AM) aimed at better understanding and evaluating beneficiaries' health care consumption and associated expenditures. In 2009, it contained data from the general health insurance regime that covers 86% of the French population; approximately 53 million people. Data are only available for a period of two years plus the current year. In addition, a permanent sample of health insurance beneficiaries (EGB) was created from the SNIIR-AM database. This is a permanent, representative cross-sectional sample of the population covered by National Health Insurance which, since 2004, monitors beneficiaries' health care consumption over a period of 20 years. It contains anonymous sociodemographic and medical characteristics and records of health care reimbursements. It was created using a systematic sampling method (1/97) on the two-digit control key of beneficiaries' national identification number and includes both current year reimbursement recipients and non-recipients. In 2009, it grouped together almost 500,000 beneficiaries covered by the National Health Insurance Fund for Salaried Workers; 77% of the population residing in France excluding public service employees and students. The EGB is used to conduct longitudinal studies as it permits tracing back patients' care paths and use of care in both hospital and office-based care environments and to calculate individual expenditures. It also permits the study of certain relatively frequent diseases characterised by a 100% reimbursement rate for certain chronic diseases and the reimbursement of tracer drugs. Eventually, the SNIIR-AM will include beneficiaries covered by all the different Health Insurance regimes in France.