Seasonal variations in onset of symptoms in Crohn's disease

Association between periodic variation of air temperature, humidity, atmospheric pressure and hospital admissions for acute occlusive mesenteric ischaemia

Referring to the intestinal ischemic injury caused by sudden interruption of the blood supply, acute mesenteric ischemia (AMI) is a highly fatal emergency with mortality rates varying from 58 to 80%. The aim of this study was to explore the effect of temperature on AMI admission. This was a retrospective, multicentric study. The medical records of 1477 patients with verified AMI who were consecutively admitted to 3 hospitals anytime between January 2010 and December 2020 were included in the study. Distributed lag non-linear model was applied, the model was adjusted for temperature, atmospheric pressure, relative humidity, year, holiday, day of the week, time and seasonality. AMI exhibited obvious sex preference, AMI patients tended to be male (M/F ratio = 2.3:1) and in their late 50 s. Hospital admissions of acute mesenteric arterial thromboembolism (AMAT) increased significantly with high temperatures on day of exposure and lag 0-14 day. The effect curve of daily average temperature on acute mesenteric venous thromboembolism (AMVT) admission was J-shaped, and the duration of cold effect was longer, while the duration of heat effect was shorter. An increase in hospital admissions of AMVT was found above 20 °C at lag 0-30. For the first time, our study indicated that temperature is significantly associated with the risk of AMI. Although it is not possible to always avoid exposure to extreme temperatures, one should be aware of dramatic temperature fluctuations and take appropriate precautions.

Assessing seasonal variations of biomarkers in inflammatory bowel disease

OBJECTIVE

Inflammatory bowel diseases are chronic pathologies characterized by a complex interplay of genetic and environmental factors, as well as aberrant immune responses. This study aimed to investigate inflammation markers' seasonality and association with disease exacerbation episodes in patients with Crohn's disease and ulcerative colitis.

METHODS

284 patients were classified based on clinical, endoscopic, and histopathological criteria. Systemic inflammation was evaluated using C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and chitotriosidase, while fecal calprotectin was measured to assess intestinal inflammation. Serum vitamin D levels and the seasonality of an activity score that combines several clinical and biological parameters were also evaluated.

RESULTS

The peak number of patients reporting endoscopic activity occurred in autumn for Crohn's disease (82%) and spring for ulcerative colitis (95%). Regarding histological activity, spring saw the highest number of patients for both diseases (72% for Crohn's disease; 87% for ulcerative colitis). Most of the inflammatory markers exhibited lower values during winter. Systemic inflammatory markers follow a slightly different trend than fecal calprotectin and differ in the two pathologies. The maximum values of intestinal inflammation were observed in autumn for Crohn's disease (784 µg/g) and in spring for ulcerative colitis (1269 µg/g). Serum vitamin D concentrations were consistently low throughout the year. Statistical analysis revealed differences between the seasons for CRP and ESR (P < 0.05).

CONCLUSION

The evolution of flares and inflammatory markers in Crohn's disease and ulcerative colitis displayed distinct seasonal patterns. Systemic inflammation did not consistently parallel intestinal inflammation.

Short-term effects of ambient temperature on acute exacerbation of inflammatory bowel disease: A nationwide case-crossover study with external validation

Inflammatory bowel disease (IBD) is an idiopathic inflammatory disorder characterized by chronic and relapsing manifestations. Several environmental factors are known as triggers for exacerbation of IBD. However, an association between exacerbation of IBD and ambient temperature is uncertain. This study aimed to estimate the risk of acute exacerbation of IBD due to ambient temperature. We performed a bidirectional case-crossover study using a nationwide claim data from South Korea. The external validation was conducted with a large prospective cohort in the United Kingdom. We confirmed significant associations between acute exacerbation of IBD and the short-term ambient temperature changes toward severe temperatures, in the cold weather (-19.4°C-4.3°C) (odd ratio [OR] = 1.13, 95% confidence interval [CI]: 1.13-1.14) and in the hot weather (21.3°C-33.5°C) (OR = 1.16, 95% CI: 1.15-1.17). However, the association was not significant in the moderate weather (4.3°C-21.3°C). The external validation suggested consistent results with additional elevation of acute exacerbation risk in the colder weather (-13.4°C to 2.6°C) (OR = 1.90, 95% CI: 1.62-2.22) and in the hotter weather (15.7°C-28.4°C) (OR = 1.41, 95% CI: 1.32-1.51). We observed and validated that the short-term ambient temperature changes were associated with acute exacerbation of IBD in the cold and hot weathers. Our findings provide evidence that temperature changes are associated with the acute exacerbation of IBD.

Changes in the clinical phenotype and behavior of pediatric luminal Crohn's disease at diagnosis in the last decade

BACKGROUND AND AIMS

The aims of this study were to describe the trends in the behavior of pediatric CD during the last decade and to describe the seasonal variation of disease presentation.

METHODS

Patients under 18 years old and diagnosed between 2009 and 2019 were included. The clinical, endoscopic, histological, and laboratory data were collected from the medical records. We analyzed the trends of these parameters according to the year and season of diagnosis.

RESULTS

654 patients were included in the study. The number of incident CD cases increased yearly. Patients diagnosed between 2015 and 2019 were younger at diagnosis (OR 2.53, p = 0.02), had more perianal diseases (OR: 2.30, p < 0.0001) and more granulomas (OR: 1.61, p = 0.003), but fewer eosinophils (OR: 0.35, p < 0.0001) and less chronic lymphoplasmacytic infiltrate (OR: 0.56, p = 0.008) as compared to the 2009-2014 cohort. There was fewer CD diagnosis during winter. Patients diagnosed in the fall had lower PCDAIs, less failure to thrive and less extensive digestive involvement. Colonic disease was significantly more frequent during summer and fall.

CONCLUSION

The clinical and histological phenotype of CD has changed over time and there are important seasonal trends in the frequency and severity on disease behavior suggesting possible disease triggers.

Seasonal changes of circulating 25-hydroxyvitamin D correlate with the lower gut microbiome composition in inflammatory bowel disease patients

Higher probability of the development of Crohn's disease (CD) and ulcerative colitis (UC) as a possible consequence of the north-south gradient has been recently suggested. Living far north or south of the equator is manifested in fluctuation of vitamin D (vitD) levels depending on the season in both healthy and affected individuals. In the present study we investigate the possible link between the seasonal serum vitD level to the microbial composition of the lower gut of Inflammatory Bowel disease (IBD) patients using 16S rRNA sequencing. Decrease of serum vitD level in winter/spring season in a cohort of 35 UC patients and 39 CD patients was confirmed. Low gut microbiota composition of patients with IBD correlated with the serum level of 25(OH)D that directly coupled to seasonal variability of the sunshine in the central European countries. It is supposed to be related to increased abundance of Actinobacteria and Proteobacteria in UC and Actinobacteria, Fusobacteria, Firmicutes and Bacteroidetes in CD. In summer/autumn period, we observed a reduction in abundance of bacterial genera typical for inflammation like Eggerthella lenta, Fusobacterium spp., Bacteroides spp., Collinsella aerofaciens, Helicobacter spp., Rhodococcus spp., Faecalibacterium prausnitzii; and increased abundance of Pediococcus spp. and Clostridium spp. and of Escherichia/Shigella spp.

Acute vascular insufficiency of intestine: incidence highest in summer, outcomes worst in winter

BACKGROUND

The incidence of acute vascular insufficiency of intestine (AVII) is on the rise in the USA and is associated with significant morbidity and mortality. Seasonal variations have been observed in the onset of several gastrointestinal diseases. It is thus far unknown whether the incidence, in-hospital mortality rates, and length of hospital stay (LOS) of AVII vary in different seasons.

AIMS

The aims of this study were to study the seasonal variations in the (1) incidence, (2) in-hospital mortality, and (3) LOS of AVII in the USA.

METHODS

We used the Nationwide Inpatient Sample to identify patients aged ≥ 18 years hospitalized from the years 2000-2014. We used the Edwards recognition with estimation of cyclic trend method to study the seasonal variation of AVII hospitalizations and z test to compare the seasonal incidences (peak-to-low ratio), mortalities, and LOS.

RESULTS

A total of 1,441,447 patients were hospitalized with AVII (0.3% of all hospitalizations). Patients with AVII were older (69.0 ± 0.1 vs 56.9 ± 0.1) and more commonly females (65.4% vs 35.5%) than patients without AVII (p < 0.001). The incidence of AVII increased through the summer to peak in September (peak/low ratio 1.028, 95% CI 1.024-1.033, p < 0.001). Patients with AVII hospitalized in winter had the highest mortality (17.3%, p < 0.001) and LOS (9.2 ± 0.7 days, p < 0.001).

CONCLUSIONS

The incidence of AVII in the USA peaks in late summer. The in-hospital mortality rates and LOS associated with AVII are the highest in winter. Physicians could be cognizant of the seasonal variations in the incidence, in-hospital mortality, and LOS of AVII.

Single high-dose oral vitamin D3 treatment in New Zealand children with inflammatory bowel disease

BACKGROUND

High-dose oral vitamin D (stoss) is a novel treatment in children with inflammatory bowel disease (IBD). Vitamin D supplementation may have benefits in IBD beyond bone health including reduced disease activity and improvements in inflammatory markers. The aim of this study was to retrospectively assess the efficacy, safety and impact on disease activity of single oral high-dose vitamin D3 therapy in New Zealand (NZ) children with IBD and vitamin D deficiency.

METHODS

In this retrospective chart review, children with IBD and vitamin D deficiency [serum 25-OH vitamin D level (25-OHD) <50 nmol/L] in Christchurch, NZ, who were managed with single high-dose vitamin D3 therapy were identified. Measurements of serum 25-OHD, calcium and standard serum inflammatory markers prior to and up to 6 months following stoss therapy were extracted from patient records. Disease activity was also defined using the Pediatric Crohn's Disease (CD) Activity Index (PCDAI) at time points before and 3 months following stoss.

RESULTS

Twenty-eight doses of stoss were given to 23 children, aged 3-16 years. Mean 25-OHD levels increased after stoss therapy from 39 nmol/L (95% CI: 37-42 nmol/L) at baseline to 189 nmol/L (148-231 nmol/L) at 1-2 months (P<0.001). All children with 1 month levels measured achieved 25-OHD >75 nmol/L. One child had a serum calcium of 2.7 (normal range, 2.2 to 2.6 mmol/L) 2 weeks after treatment, which normalized on repeat testing 10 days later. PCDAI scores, mean platelet count, erythrocyte sedimentation rate (ESR) and C reactive protein (CRP) all reduced significantly from baseline to 3 months following stoss therapy.

CONCLUSIONS

Single high-dose oral vitamin D therapy was used successfully and safely to manage vitamin D deficiency in these children with IBD. An improvement in inflammatory markers and disease activity scores also occurred following stoss therapy.

Low Sun Exposure and Vitamin D Deficiency as Risk Factors for Inflammatory Bowel Disease, With a Focus on Childhood Onset

The incidence and prevalence of inflammatory bowel disease (IBD) are increasing worldwide. Some ecological studies show increasing incidence with increasing latitude. Ambient ultraviolet radiation varies inversely with latitude, and sun exposure of the skin is a major source of vitamin D. Vitamin D deficiency is common in patients with IBD. Sun exposure and vitamin D have immune effects that could plausibly reduce, or be protective for, IBD. One quarter of new IBD cases are diagnosed in childhood or adolescence, but most research is for adult-onset IBD. Here, we review the evidence for low sun exposure and/or vitamin D deficiency as risk factors for IBD, focusing where possible on pediatric IBD, where effects of environmental exposures may be clearer. The literature provides some evidence of a latitude gradient of IBD incidence, and evidence for seasonal patterns of timing of birth or disease onset is inconsistent. High prevalence of vitamin D deficiency occurs in people with IBD, but cannot be interpreted as being a causal risk factor. Evidence of vitamin D supplementation affecting disease activity is limited. Further research on predisease sun exposure and well-designed supplementation studies are required to elucidate whether these potentially modifiable exposures are indeed risk factors for IBD.

Academic Stress May Contribute to the Onset of Pediatric Inflammatory Bowel Diseases

It is currently unclear whether seasonality affects the onset of inflammatory bowel diseases (IBDs: Crohn disease and ulcerative colitis) in children. Here, we examined the records of pediatric patients with IBD diagnosed between 2009 and 2015 in a discovery cohort of 169 cases and a validation cohort of 122 subjects, where the month of symptoms onset could be determined. No seasonal patterns could be identified in respect to conception, birth, and disease onset. An annual rhythm of symptomatic onset, however, correlating with academic semesters was identified. IBD symptoms in the discovery cohort presented significantly more (P = 0.0218) during 5 months including the initiation (August, September, January) and the termination of academic semesters (December, May) compared to any other 5 months of the year. This observation was validated in the independent cohort (P < 0.0001). Our findings imply that academic stress may contribute to disease onset in pediatric IBD, which may improve timely diagnosis.

The Impact of Cold Spells on the Incidence of Infectious Gastroenteritis and Relapse Rates of Inflammatory Bowel Disease: A Retrospective Controlled Observational Study

Goals

We aimed to assess the impact of very cold days on inflammatory bowel disease (IBD) flares and infectious gastroenteritis (IG). We defined a cold day using the World Meteorological definition of an ice day, which is a day with a maximum temperature below 0°C.

Background

Recently, we have shown that heat waves increase the risk for IG and IBD flares.

Study

We retrospectively collected data from 738 IBD and 786 IG patients admitted to the University Hospital of Zurich between 2001 and 2005 and from 506 patients with other noninfectious chronic intestinal inflammations as controls. Climate data were received by the Swiss Federal Office for Meteorology and Climatology.

Results

There was no evidence for an increased risk of IBD flares (relative risk, RR = 0.99, 95% confidence interval, CI: 0.72-1.33, p = 0.94) or IG flares (RR = 1.16, 95% CI: 087-1.52, p = 0.30) on very cold days. This negative finding was confirmed in alternative formulations with lagged or cumulative (possibly lagged) effects.

Conclusion

In this retrospective controlled observational study, no evidence for an increase in hospital admissions due to flares of IBD and IG during cold days was observed. This may be attributed to not relevantly altered bacterial growth conditions during cold days compared to heat waves.

Age at onset is associated with the seasonal pattern of onset and exacerbation in inflammatory bowel disease

BACKGROUND

Environmental factors are suggested to affect the pathogenesis of several diseases, including inflammatory bowel disease (IBD). The seasonality of disease onset and exacerbation in IBD, however, are not well established. We herein aimed to clarify the disease seasonality and to investigate the underlying characteristics in IBD patients exhibiting seasonality of the disease course.

METHODS

This was a multicenter observational study comprising 20 institutions (Osaka Gut Forum) in Japan. Data were collected from November 2013 to August 2014 using survey forms for physicians and questionnaires for patients. Multivariate analysis was performed to clarify the independent factors affecting disease seasonality.

RESULTS

A total of 1055 patients, including 298 patients with Crohn's disease (CD) and 757 patients with ulcerative colitis (UC), were enrolled. The proportion of CD patients with disease onset in the summer was significantly larger than that in the other seasons, while UC patients exhibited no seasonality of disease onset. More than half of the IBD patients (51.1%) experienced seasonal exacerbation of IBD, and winter was the most common season for disease exacerbation in both CD and UC patients. Seasonality of disease onset and exacerbation was observed in young-onset patients (≤40 years old), but not in elderly-onset patients. Age at onset was independently associated with the seasonality of both disease onset and exacerbation.

CONCLUSIONS

Seasonality of disease onset and exacerbation was observed especially in young-onset IBD patients. Underlying pathophysiologic triggers for disease initiation and exacerbation may be influenced by age at disease onset.

Seasonality and autoimmune diseases: The contribution of the four seasons to the mosaic of autoimmunity

Autoimmune diseases (ADs) are a heterogeneous groups of diseases that occur as a results of loss of tolerance to self antigens. While the etiopathogeneis remain obscure, different environmental factors were suggested to have a role in the development of autoimmunity, including infections, low vitamin D levels, UV radiation, and melatonin. Interestingly, such factors possess seasonal variation patterns that could influence disease development, severity and progression. Vitamin D levels which reach a nadir during late winter and early spring is correlated with increased disease activity, clinical severity as well as relapse rates in several disease entities including multiple sclerosis (MS), non-cutaneous flares of systemic lupus erythematosus (SLE), psoriasis, and rheumatoid arthritis (RA). Additionally, immunomodulatory actions of melatonin secretion ameliorate the severity of several ADs including MS and SLE. Melatonin levels are lowest during spring, a finding that correlates with the highest exacerbation rates of MS. Further, melatonin is postulated to be involved in the etiopathogenesis of inflammatory bowel diseases (IBD) through it influence on adhesion molecule and therefore transcription factor expression. Moreover, infections can mount to ADs through pro-inflammatory cytokine release and human antigen mimicry. Seasonal patterns of infectious diseases are correlated with the onset and exacerbation of ADs. During the winter, increased incidence of Epstein-Barr virus (EBV) infectious are associated with MS and SLE flares/onset respectively. In addition, higher Rotavirus infections during the winter precedes type 1 diabetes mellitus onset (T1DM). Moreover, Escherichia coli (E. coli) infection prior to primary biliary cirrhosis (PBC) and T1DM disease onset subsequent to Coxachievirus infections are seen to occur during late summer, a finding that correlate with infectious agents' pattern of seasonality. In this review, the effects of seasonality on the onset, relapses and activity of various ADs were discussed. Consideration of seasonal variation patterns of ADs can possibly provide clues to diseases pathogenesis and lead to development of new approaches in treatment and preventative care.

Associations of seasonal patterns and vitamin D levels with onset and flares of pediatric inflammatory bowel disease

BACKGROUND

As inflammatory bowel disease (IBD) might be associated with environmental factors such as seasonal patterns and low vitamin D levels we aimed to assess their association with IBD onset and flares in a large cohort of children.

METHODS

The records of 623 pediatric onset IBD patients were reviewed retrospectively including age at onset, gender, severity indices, month of first symptom, and vitamin D levels at diagnosis. For a subgroup of patients, data included date of first flare and vitamin D levels during flare and remission.

RESULTS

Median age at diagnosis was 14 years (IQR 11.66-15.58). Disease onset did not vary significantly between either month (P=0.367) or seasons (P=0.460). Vitamin D deficiency at the time of diagnosis was prevalent in 21% of patients with no significant association with month, season or disease's type. Vitamin D deficiency was significantly more prevalent in patients with malnutrition (P<0.001) and was associated with hypoalbuminemia (P=0.02) but did not correlate with low bone mineral density. Analysis of 169 first flares showed that flares were more common in June and less common in April (P=0.016). Mean vitamin D level was significantly lower during flares compared with remission (55.25±19.28 vs. 64.16±26.6, respectively, P=0.012).

CONCLUSIONS

IBD onset in school aged children is not associated with seasonal patterns whereas flares may follow a specific monthly pattern. Disease flares are associated with low vitamin D blood levels. Vitamin D deficiency is associated with malnutrition and hypoalbuminemia.

Impact of Seasons and Festivals on the Onset of Acute Pancreatitis in Shanghai, China

OBJECTIVES

Seasonal variation on acute pancreatitis (AP) has not been investigated in Eastern Asia. The aims of the study were to assess the association of the onset of AP with the occurrence of seasons and Chinese festivals and to investigate trends in AP incidence in Shanghai, China.

METHODS

From January 2009 to December 2014, a total of 1780 patients with AP were considered. The incidence was assessed by different etiology and severity. Monthly disease prevalence was investigated to explore the seasonal variation. The prevalence on weekdays, weekends, and festivals was evaluated to establish any weekly or festival influences in AP.

RESULTS

Acute pancreatitis increased from 30.5 per 100,000 in 2009 to 39.2 in 2014 (5.1% annual increase), with greatest increases in alcoholic (19.8% annually) and severe AP (13.7% annually). Time series analysis indicated that prevalence was significantly higher form February to May (spring) and from September to October (autumn). Acute pancreatitis increased during Chinese festivals, 17% and 28% greater than that observed on weekdays and weekends, respectively. Prevalence was greatest in Chinese Spring Festival week.

CONCLUSIONS

Acute pancreatitis increased in Shanghai and had a seasonal variation, with a higher frequency of events in the spring and autumn. Chinese festivals are associated with a high prevalence of AP.

Seasonal variation in occurrence of ischemic colitis: a retrospective study

Objectives We aimed to identify the clinical characteristics of ischemic colitis (IC) and to investigate the occurrence of seasonal variation. Methods From January 2008 to December 2014, 368 had IC as the reason for their admission. A total of 364 patients were enrolled in this study. We investigated patient characteristics and seasonal variations in incidence. Results The mean age (±standard deviation) of patients with IC at diagnosis was 66.8 (±16.9) years. Most patients had abdominal pain (341 cases), hematochezia (337 cases), and diarrhea (199 cases) as their chief complaints. The clinical courses of the disease were classified as transient (294 cases), stricture (17 cases), gangrenous (2 cases), and indeterminate types (51 cases). Although IC tended to occur less frequently in winter, the seasonal difference was not significant. Conclusion There is currently no evidence for seasonal variation in hospital admissions for IC.

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.

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.

Diagnostic Delay in Romanian Patients with Inflammatory Bowel Disease: Risk Factors and Impact on the Disease Course and Need for Surgery

BACKGROUND

The epidemiology of inflammatory bowel disease [IBD] in Eastern Europe is poorly understood, particularly with regard to diagnostic delay. Here we investigated the factors leading to delayed diagnosis and the effect of the delay on several disease progression and outcome measures.

METHODS

A total of 1196 IBD cases [682 ulcerative colitis [UC], 478 Crohn's disease [CD], 36 indeterminate colitis] from the Romanian national registry IBDPROSPECT were reviewed. Standard clinical and demographic factors were evaluated as predictors of a long diagnostic delay in both CD and UC. Diagnostic delay was subsequently evaluated as a potential risk factor for bowel stenoses, bowel fistulas, perianal fistulas, perianal surgery, and intestinal surgery in CD patients.

RESULTS

The median diagnostic delay was significantly longer in CD [5 months] than in UC [1 month] patients [p < 0.001]. Compared with 5 months for UC patients, 75% of CD patients were diagnosed within 18 months of symptom onset. In CD patients, extra-ileal location was a protective factor (odds ratio [OR], 0.5; p = 0.03), whereas being an active smoker [OR, 2.09; p = 0.01] and symptom onset during summer [OR, 3.35; p < 0.001] were independent risk factors for a long diagnostic delay [> 18 months]. In UC patients, an age > 40 years was a protective factor [OR, 0.68; p = 0.04] for a long delay. Regarding outcomes, a long diagnostic delay in CD patients positively correlated with bowel stenoses [OR, 3.38; p < 0.01] and any IBD-related surgery [OR, 1.95; p = 0.03] and had a positive trend for intestinal fistulas [OR, 2.64; p = 0.08] and perianal fistulas [OR, 2.9; p = 0.07]. Disease duration since diagnosis positively correlated with bowel stenoses [OR, 1.04; p = 0.04], any IBD-related surgery [OR, 1.04; p = 0.02], and intestinal surgery [OR, 1.07; p < 0.01].

CONCLUSIONS

A long diagnostic delay in IBD correlates with an increased frequency of bowel stenoses and need for IBD-related surgery.

Seasonal variations in onset and exacerbation of inflammatory bowel diseases in children

BACKGROUND

Studies have suggested that inflammatory bowel diseases (IBD) follow a seasonal pattern with regard to their onset and exacerbations. The aim of this study is to determine if there is any seasonal pattern to the onset and exacerbation of IBD in the pediatric population and if the birth of children diagnosed with IBD follows a seasonal pattern.

METHODS

Patients between the ages of 1 and 21 years and with a diagnosis of IBD established between July 1992 and July 2012 were included. Their onset and exacerbations of IBD (year and season) were recorded. The birth dates of the patients were aggregated to determine whether a seasonal birth pattern existed amongst them.

RESULTS

A total of 170 children were included in this study; 34% of patients had their onset in the fall and 19% of them had their onset in the summer. The total number of documented exacerbations was 358 and the median number of exacerbations was two, with a range of 1-11. IBD exacerbations were generally uniformly distributed throughout the year. We did not observe any specific season where children with IBD tended to be born.

CONCLUSIONS

Our data suggests that the onset of symptoms of IBD tends to have a seasonal trend with the highest incidence in the fall. However, we did not observe any association between seasonality and exacerbations in the pediatric population. Moreover, there was no specific season in which children with IBD tended to be born in greater numbers.

Seasonal Variation in Flares of Intestinal Behçet's Disease

BACKGROUND

There have been numerous investigations into the seasonality of several autoimmune diseases and inflammatory bowel disease in an effort to better understand the epidemiology and pathogenesis of these conditions. However, the relationship between the season and disease activity of intestinal Behçet's disease has not been investigated.

AIMS

This study aimed to evaluate the seasonal pattern of exacerbations of intestinal Behçet's disease.

METHODS

We evaluated 268 consecutive patients with intestinal Behçet's disease who were diagnosed and treated between November 1990 and March 2010 at Severance Hospital, Yonsei University, Seoul, Korea. Patient demographics, onset of symptoms, total number of relapses, and the month of each relapse were recorded. The relationship between the season and flares of intestinal Behçet's disease was analyzed.

RESULTS

A total of 339 relapses occurred in 142 patients (53 %). The median age at diagnosis was 39 (10-73) years; the median follow-up duration was 74 (7-372) months. The peak seasons for relapse were spring and autumn, especially the months of May and September (p value <0.001). Compared with winter, spring and autumn had higher rates of flares (HR 1.92 and 1.91, respectively, p value <0.001).

CONCLUSIONS

In this study, intestinal Behçet's disease demonstrated a biphasic pattern (peaks in spring and autumn) in exacerbations of disease, suggesting that seasonal or exogenous factors may be involved in the flares of intestinal Behçet's disease.

Seasonal variation in onset and relapse of IBD and a model to predict the frequency of onset, relapse, and severity of IBD based on artificial neural network

BACKGROUND

Previous research has yielded conflicting data as to whether the natural history of inflammatory bowel disease follows a seasonal pattern. The purpose of this study was (1) to determine whether the frequency of onset and relapse of inflammatory bowel disease follows a seasonal pattern and (2) to establish a model to predict the frequency of onset, relapse, and severity of inflammatory bowel disease (IBD) with meteorological data based on artificial neural network (ANN).

METHOD

Patients with diagnosis of ulcerative colitis (UC) or Crohn's disease (CD) between 2003 and 2011 were investigated according to the occurrence of onset and flares of symptoms. The expected onset or relapse was calculated on a monthly basis over the study period. For artificial neural network (ANN), patients from 2003 to 2010 were assigned as training cohort and patients in 2011 were assigned as validation cohort. Mean square error (MSE) and mean absolute percentage error (MAPE) were used to evaluate the predictive accuracy.

RESULTS

We found no seasonal pattern of onset (P = 0.248) and relapse (P = 0.394) among UC patients. But, the onset (P = 0.015) and relapse (P = 0.004) of CD were associated with seasonal pattern, with a peak in July and August. ANN had average accuracy to predict the frequency of onset (MSE = 0.076, MAPE = 37.58%) and severity of IBD (MSE = 0.065, MAPE = 42.15%) but high accuracy in predicting the frequency of relapse of IBD (MSE = 0.009, MAPE = 17.1%).

CONCLUSION

The frequency of onset and relapse in IBD showed seasonality only in CD, with a peak in July and August, but not in UC. ANN may have its value in predicting the frequency of relapse among patients with IBD.

Association between 25(OH)D Level, Ultraviolet Exposure, Geographical Location, and Inflammatory Bowel Disease Activity: A Systematic Review and Meta-Analysis

Background

There is no consensus on the vitamin D levels and inflammatory bowel disease (IBD).

Aim

To conduct a systematic review and meta-analysis to analyze the relationship between IBD and 25(OH)D, sun exposure, and latitude, and to determine whether vitamin D deficiency affects the severity of IBD.

Methods

We searched the PubMed, EBSCO, and ClinicalTrials.gov databases to identify all studies that assessed the association between 25(OH)D, sun exposure, latitude, and IBD through November 1, 2014, without language restrictions. Studies that compared 25(OH)D levels between IBD patients and controls were selected for inclusion in the meta-analysis. We calculated pooled standardized mean differences (SMDs) and odds ratios (ORs).

Results

Thirteen case-control studies investigating CD and 25(OH)D levels were included, and eight studies part of above studies also investigated the relationship between UC and 25(OH)D. Both CD patients (SMD: 0.26 nmol/L, 95% confidence interval [CI]: 0.09–0.42 nmol/L) and UC patients (SMD: 0.5 nmol/L, 95% CI: 0.15–0.85 nmol/L) had lower levels of 25(OH)D than controls. In addition, CD patients and UC patients were 1.95 times (OR, 1.95; 95% CI, 1.48–2.57) and 2.02 times (OR, 2.02; 95% CI, 1.13–3.60) more likely to be 25(OH)D deficient than controls. We also included 10 studies investigating the relationship between CD activity and vitamin D. Results showed that patients with active CD (CD Activity Index≥150) were more likely to have low vitamin D levels. In addition, whether low sun exposure and high latitude were related to a high morbidity of CD need to be provided more evidence.

Conclusion

Our study shows that IBD patients have lower vitamin D levels. For active CD patients, vitamin D levels were low. These findings suggest that vitamin D may play an important role in the development of IBD, although a direct association could not be determined in our study.

Seasonal clustering in inflammatory bowel disease: a single centre experience

BACKGROUNDS AND AIMS

External stimuli are considered as possible triggers for the onset of inflammatory bowel disease (IBD), and particularly chronic ulcerative colitis (CUC) in genetically susceptible individuals. Our aims were to investigate monthly clustering-patterns in the onset of symptoms and diagnosis of IBD, as well as health seeking behavior in those individuals.

MATERIALS AND METHODS

Two hundred and eighty-two consecutive patients with IBD were included. Onset of symptoms (month) and delay to diagnosis were analyzed. Kruskal-Wallis and Roger's test were used to analyze for statistical patterns in seasonal clustering.

RESULTS

There were 181 males and 101 females with IBD; mean age: 40 ± 14.7 years (median: 38, range: 14-79 years). The peak number of IBD cases was seen in winter/early spring, with the lowest numbers in autumn, which reached statistical significance in the CUC group (p: 0.029). Seasonal changes were not significantly affected by gender. The time delay to diagnosis from symptom onset was 3.0 ± 2.3 months in males (median: 2, range: 0-12 months) vs 3.2 ± 3.2 months (median: 2, range: 0-18 months) in females (not statistically significant).

CONCLUSION

Our results show a seasonal relation in IBD cases, particularly in CUC, which may suggest external stimuli acting as a precipitant to IBD in susceptible individuals. There was a delay between symptom onset and CUC diagnosis, which was not felt to be clinically significant.

Vitamin D therapy in inflammatory bowel diseases: who, in what form, and how much?

BACKGROUND

The north–south geographical gradient of inflammatory bowel disease (IBD) prevalence, its epidemiology, the genetic association of vitamin D receptor polymorphisms, and results in animal models suggest that vitamin D plays an important role in the pathogenesis of IBD.

AIMS

The purpose of this review was to critically appraise the effectiveness and safety of vitamin D therapy in patients with IBD.

METHODS

MEDLINE, Scopus and Google Scholar were searched from inception to May 20, 2014 using the terms ‘Crohn’s disease’, ‘ulcerative colitis’ and ‘vitamin D’. Results: Vitamin D deficiency is common in patients with IBD. Limited clinical data suggest an association between low vitamin D concentration and increased disease activity in both ulcerative colitis (UC) and Crohn’s disease (CD). To date, only two small open label trials and one randomized controlled trial have shown a positive effect of vitamin D supplementation on disease activity in patients with CD; no effect has been shown for UC. An optimal vitamin D supplementation protocol for patients with IBD remains undetermined, but targeting serum 25-hydroxy vitamin D [25(OH)D] levels between 30 and 50 ng/mL appears safe and may have benefits for IBD disease activity. Depending on baseline vitamin D serum concentration, ileal involvement in CD, body mass index, and perhaps smoking status, daily vitamin D doses between 1800–10,000 international units/day are probably necessary.

CONCLUSION

Increasing preclinical and clinical evidence suggests a role for vitamin D deficiency in the development and severity of IBD. The possible therapeutic role of vitamin D in patients with IBD merits continued investigation.

Severe eosinophilic infiltration in colonic biopsies predicts patients with ulcerative colitis not responding to medical therapy

AIM

Eosinophils are potent proinflammatory cells that are involved in the pathogenesis of ulcerative colitis (UC). We evaluated the infiltration of eosinophils into the lamina propria in patients with active and inactive ulcerative colitis (UC) and investigated its clinical significance, among other variables, in predicting the outcome of medical treatment in active disease.

METHOD

We studied colorectal biopsy specimens from 18 UC patients with disease in long-standing remission, from 22 patients with active disease who responded to therapy (12 with complete response and 10 with partial response) and from 10 patients who were nonresponders. Demographic information was obtained at baseline, and clinical, endoscopic and laboratory data were obtained at baseline and 12 weeks post-treatment. We evaluated five histological features: mucosal ulceration; mucosal erosions; crypt abscesses; cryptitis; and eosinophilic infiltration of the lamina propria. The severity of these lesions was graded as: none or minimal; mild; moderate; or severe. Statistical analyses were performed between responders and nonresponders for differences in demographic, clinical, laboratory, endoscopic and histological parameters.

RESULTS

Laboratory, endoscopic and histological parameters were significantly improved after treatment only in the complete responders group. Analyses of baseline data revealed no significant differences in parameters between complete or partial responders and nonresponders, except for a less severe eosinophilic infiltration of lamina propria in complete responders (P < 0.05). Multiple logistic regression analysis showed that severe eosinophilic infiltration in colonic biopsies was the most significant predictor of poor response to medical therapy.

CONCLUSION

Assessing the severity of eosinophilic infiltration in the lamina propria of colonic biopsies in patients with ulcerative colitis could be a valuable predictive tool of response to medical therapy.

Incidence and prevalence of inflammatory bowel diseases in gastroenterology primary care setting

BACKGROUND

The incidence of inflammatory bowel diseases (IBDs) has markedly increased over the last years, but no epidemiological study has been performed in gastroenterology primary care setting. We describe the epidemiology of IBD in a gastroenterology primary care unit using its records as the primary data source.

METHODS

Case finding used predefined read codes to systematically search computer diagnostic and prescribing records from January 2009 to December 2012. A specialist diagnosis of Ulcerative colitis (UC), Crohn's disease (CD), inflammatory bowel disease unclassified (IBDU) or segmental colitis associated with diverticulosis (SCAD), based on clinical, histological or radiological findings, was a prerequisite for the inclusion in the study. Secondary, infective and apparent acute self-limiting colitis were excluded.

RESULTS

We identified 176 patients with IBD in a population of 94,000 with a prevalence 187.2/100,000 (95% CI: 160.6-217.0). Between 2009 and 2012 there were 61 new cases. In particular, there were 23 new cases of UC, 19 new cases of CD, 15 new cases of SCAD, and 4 new cases of IBDU. The incidence of IBD was 16.2/100,000 (95% CI 12.5-20.7) per year. The incidence per year was 6/100,000 (95% CI 3.8 to 8.9) for UC, 5/100,000 (95% CI 3.0-7.7) for CD, 4/100,000 (95% CI 2.3-6.5) for SCAD, and 1/100,000 (95% CI 0.3-2.6) for IBDU.

CONCLUSIONS

We assessed for the first time which is the prevalence and incidence of IBD in a gastroenterology primary care unit. This confirms that specialist primary care unit is a key factor in providing early diagnosis of chronic diseases.

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.

Heat waves, incidence of infectious gastroenteritis, and relapse rates of inflammatory bowel disease: a retrospective controlled observational study

OBJECTIVES

The objective of this study was to evaluate the effect of heat waves on flares of inflammatory bowel disease (IBD) and infectious gastroenteritis (IG).

METHODS

In this retrospective controlled observational study, data from 738 IBD and 786 IG patients admitted to the University Hospital of Zurich in the years 2001-2005, as well as from 506 other noninfectious chronic intestinal inflammations, which were used as control, were collected. Climate data were obtained from the Swiss Federal Office for Meteorology and Climatology.

RESULTS

The presence of a heat wave increased the risk of IBD flares by 4.6% (95% confidence interval (CI): 1.6-7.4%, P=0.0035) and of IG flares by 4.7% (95% CI: 1.8-7.4%, P=0.0020) for every additional day within a heat wave period. In the control group there was no significant effect (95% CI: -6.2-2.9%, P=0.53). Screening of alternative forms for the effect of heat waves suggested that for IG the effect is strongest when lagged by 7 days (risk increase per day: 7.2%, 95% CI: 4.6-9.7%, P<0.0001), whereas for IBD no such transformation was required. Other formulations with additive effects, interactions between heat waves and time of the year, and additional adjustments for daily average temperature did not show any improvement in model fit.

CONCLUSIONS

In this retrospective controlled observational study, we found a substantial increase in hospital admissions because of flares of IBD and IG during heat wave periods. Whereas the effect on IG is strongest with a delay of 7 days, the effect on IBD flares is immediate, suggesting different mechanisms.

Seasonal variation in months of birth and symptom flares in Korean patients with inflammatory bowel disease

Background/Aims

Seasonal variation may influence the development and exacerbation of inflammatory bowel disease (IBD). However, most epidemiologic studies on this topic have been conducted in Western countries. The purpose of this study was to determine whether birth dates and symptom flares follow a seasonal pattern in Korean patients with IBD.

Methods

Patients with a diagnosis of IBD established between January 2003 and December 2010 were investigated at six university hospitals in Korea. The expected births and flares, with a uniform distribution during the year and considering differences in the number of days in the months of 1 year, were calculated.

Results

A total of 411 patients with ulcerative colitis (UC) and 316 patients with Crohn disease (CD) were included in the study. Birth during the winter period, and especially in January and February, was associated with an increased risk of IBD, especially in UC patients. The symptom flares of CD patients occurred most frequently in the spring, with a nadir in the autumn. However, no disease flare seasonality was noted for UC patients.

Conclusions

Our data suggest that seasonally varying environmental factors during pregnancy and the postpartum period are associated with a susceptibility to IBD later in life and that exacerbations of CD are influenced by seasonal factors.

Vitamin D metabolism and signaling in the immune system

Vitamin D has emerged as a pleiotropic regulator of human physiology, and recent work has revealed that it has several roles in control of human immune system function. Vitamin D was originally characterized for its role in calcium homeostasis, and the active form, 1,25-dihydroxyvitamin D (1,25D), can be produced in the kidney by 1α-hydroxylation of circulating 25-hydroxyvitamin D catalyzed by the enzyme CYP27B1. Renal CYP27B1 expression is regulated by calcium regulatory inputs, and 1,25D produced in the kidney was thought to function largely as an endocrine hormone. However, it is now clear that CYP27B1 is expressed in numerous tissues, and that 1,25D acts at several sites in the body in an intracrine or paracrine manner. In particular, both CYP27B1 and the vitamin D receptor (VDR) are expressed in several cell types in the immune system, where CYP27B1 production is controlled by a number of immune-specific inputs. Recent research has opened several windows on the molecular mechanisms by which 1,25D signaling regulates both innate and adaptive immune responses in humans. Moreover, intervention trials are beginning to provide evidence that vitamin D supplementation can bolster clinical responses to infection. This review will discuss recent developments in our understanding of how immune signaling controls local vitamin D metabolism and how, in turn, the 1,25D-bound VDR modulates immune system function. A particular emphasis will be placed on the interplay between vitamin D signaling and signaling through different classes of pattern recognition receptors in the production of antimicrobial peptides during innate immune responses to microbial infection.

Intestinal cancer risk in Crohn's disease: a meta-analysis

AIM OF THE STUDY

To clarify the intestinal cancer risk in Crohn's disease (CD).

METHODS

20 clinical studies (1965-2008) with a total of 40,547 patients with Crohn's disease-associated cancer (CDAC) were included in the meta-analysis ("inverse variance weighted" method).

RESULTS

The incidence of CDAC in any CD patient was 0.8/1,000 person years duration (pyd) (CI, 0.6-1.0). The incidences of different carcinomas were: colorectal cancer 0.5/1,000 pyd (CI, 0.3-0.6), small bowel carcinoma 0.3/1,000 pyd (CI, 0.1-0.5), and cancers arising from CD-associated fistulae 0.2/1,000 pyd (CI, 0.0-0.4). Compared to the incidence in an age-matched standard population, the risk of colorectal cancer was increased by factor 2-3 and of small bowel cancer by factor 18.75, respectively. Mean patient age at diagnosis of CD-associated colorectal cancer was 51.5 years, thus 20 years earlier than in a standard population. The mean duration of CD until diagnosis of CDAC was 18.3 years. Duration of CD, age at diagnosis of CD, and anatomical area of CD involvement had no significant influence on cancer incidence.

CONCLUSIONS

CD is a risk factor for colorectal cancer, small bowel cancer, and fistula cancer; however, compared to ulcerative colitis, cancer risk is moderate.

Direct and indirect induction by 1,25-dihydroxyvitamin D3 of the NOD2/CARD15-defensin beta2 innate immune pathway defective in Crohn disease

Vitamin D signaling through its nuclear vitamin D receptor has emerged as a key regulator of innate immunity in humans. Here we show that hormonal vitamin D, 1,25-dihydroxyvitamin D(3), robustly stimulates expression of pattern recognition receptor NOD2/CARD15/IBD1 gene and protein in primary human monocytic and epithelial cells. The vitamin D receptor signals through distal enhancers in the NOD2 gene, whose function was validated by chromatin immunoprecipitation and chromatin conformation capture assays. A key downstream signaling consequence of NOD2 activation by agonist muramyl dipeptide is stimulation of NF-kappaB transcription factor function, which induces expression of the gene encoding antimicrobial peptide defensin beta2 (DEFB2/HBD2). Pretreatment with 1,25-dihydroxyvitamin D(3) synergistically induced NF-kappaB function and expression of genes encoding DEFB2/HBD2 and antimicrobial peptide cathelicidin in the presence of muramyl dipeptide. Importantly, this synergistic response was also seen in macrophages from a donor wild type for NOD2 but was absent in macrophages from patients with Crohn disease homozygous for non-functional NOD2 variants. These studies provide strong molecular links between vitamin D deficiency and the genetics of Crohn disease, a chronic incurable inflammatory bowel condition, as Crohn's pathogenesis is associated with attenuated NOD2 or DEFB2/HBD2 function.

[The placebo effect in inflammatory bowel disease]

Since time immemorial, placebos have been used in the treatment of patients with very different diseases. Interest in these substances has recently been renewed, since the use of placebo-controlled clinical trials has become the most useful tool to demonstrate the efficacy of a particular drug in patients with specific diseases. In inflammatory bowel disease (IBD), both in Crohn's disease and in ulcerative colitis, highly significant results have been obtained in patients in the placebo arm of clinical trials, surpassing even those achieved with drugs in other studies. Patients with IBD show certain characteristics that make them especially susceptible to the placebo effect: IBD are chronic diseases occurring in flares and pain is one of the main symptoms. In future, the placebo effect should be adequately quantified in the distinct clinical scenarios of IBD in order to design clinical trials that could demonstrate the true efficacy of the treatments investigated.

Inflammatory Bowel Disease in South Limburg (the Netherlands) 1991-2002: Incidence, diagnostic delay, and seasonal variations in onset of symptoms

BACKGROUND AND AIMS

Increasing incidence in Inflammatory Bowel Disease (IBD) has been suggested. Recent data on population based incidence rates within Europe are however scarce. Primary aim was to investigate prospectively the incidence of IBD within a well-defined geographical and administrative area of the Netherlands, the South Limburg IBD registry. Secondary aims were to study the duration of symptoms before diagnosis (lag time) and seasonal influences on the incidence of IBD.

METHODS

The incidence was examined using standardized registration of all newly diagnosed IBD patients, between 1-1-1991 and 1-1-2003. Medical records were reviewed to verify the diagnosis. At inclusion, diagnostic lag time was registered in months.

RESULTS

Age standardized incidence rates per 100,000 person-years (p-y) were: Crohn's Disease, male 4.84, female 7.58; Ulcerative Colitis, male 8.51, female 6.92; and Indeterminate Colitis, male 1.05, female 0.93. Incidence rates did not significantly changes over time in either Crohn's Disease, Ulcerative Colitis or Indeterminate Colitis. Lag time was 5 (0-360) months in Crohn's Disease, 3.0 (0-480) months in Ulcerative Colitis and 3.0 (0-180) months in Indeterminate Colitis. Lag time was not significantly different between the periods 1991-1993 and 2000-2002, and no statistical differences in the onset of symptoms per calendar month or season were found.

CONCLUSIONS

Our results, from the South Limburg region (the Netherlands), show no significant change in incidence rates of IBD. The incidence found is relatively high compared to other European countries. Lag time did not change during the study period, and seasonal influence of incidence rates could not be confirmed.

Seasonality in flares and months of births of patients with ulcerative colitis in a Chinese population

BACKGROUND AND AIMS

Reports on seasonality in flares or months of births of inflammatory bowel disease patients have been inconsistent, but little data are available in a Chinese population. The aim of this study was to determine whether symptom flares and births of ulcerative colitis (UC) patients follow a seasonal pattern.

METHODS

Patients with a diagnosis of UC established between January 1990 and December 2007 were investigated according to the occurrence of flares of symptoms and months of births. The expected flares or births were calculated on a monthly basis over the study period, taking into consideration the difference in the number of days in the month in each year.

RESULTS

A total of 409 UC patients were included in the study, and 1030 flares of symptoms were determined. The peak number of flares occurred during the spring and summer, especially in June, while the nadir occurred in the winter, especially in January (chi(2) ((11 df))=32.74304, P<0.005). The symptom flares also occurred more frequently in the spring-summer period than in the autumn-winter period (chi(2) ((3 df))=22.1269, P<0.001). There was no statistical difference in birth distribution on a monthly or seasonal (spring, summer, autumn, winter) basis. However, the births of UC patients occurred more frequently in the autumn-winter period than in the spring-summer period when the data were merged into these two seasonal components (chi(2) ((1 df))=5.255607, P<0.025).

CONCLUSIONS

The data indicate that the symptom flares of UC occurred more frequently in the spring and summer, while the births of UC patients occurred more often in the autumn and winter. Environmental recurring factors may be associated with the symptom flares of UC, and these factors during pregnancy or postpartum may be associated with susceptibility to UC later in life.

Hypothesis--ultraviolet-B irradiance and vitamin D reduce the risk of viral infections and thus their sequelae, including autoimmune diseases and some cancers

Many viral infections reach clinical significance in winter, when it is cold, relative humidity is lowest and vitamin D production from solar ultraviolet-B irradiation is at its nadir. Several autoimmune diseases, such as multiple sclerosis, type 1 diabetes mellitus and asthma, are linked to viral infections. Vitamin D, through induction of cathelicidin, which effectively combats both bacterial and viral infections, may reduce the risk of several autoimmune diseases and cancers by reducing the development of viral infections. Some types of cancer are also linked to viral infections. The cancers with seemingly important risk from viral infections important in winter, based on correlations with increasing latitude in the United States, an index of wintertime solar ultraviolet-B dose and vitamin D, are bladder, prostate, testicular and thyroid cancer, Hodgkin's and non-Hodgkin's lymphoma, and, perhaps, gastric cancer. The evidence examined includes the role of viruses in the etiology of these diseases, the geographic and seasonal variation of these diseases, and the time of life when vitamin D is effective in reducing the risk of disease. In general, the evidence supports the hypothesis. However, further work is required to evaluate this hypothesis.

Gender-related and city- and countryside-related differences in patients with ulcerative colitis in a Chinese population

OBJECTIVE

The purpose of this study is to determine gender-related and city- and countryside-related differences of ulcerative colitis in a Chinese population, and to determine information on the role of lifestyle in the onset of ulcerative colitis.

METHODS

Patients with a diagnosis of ulcerative colitis established between Jan 2000 and Dec 2007 were investigated according to the age, gender and inductive factors of onset. Assessment of living condition of the patients was performed according to the place of living: city or countryside. Statistical analysis was performed using the chi-square test.

RESULTS

A total of 293 ulcerative colitis patients were involved in the study. The onset age of the rural patients was earlier than that of the urban patients (p=0.00295), while there was no difference in onset age between male and female patients (p=0.067995). Some inductive factors, such as psychological stress, fatigue, cold catching, and spicy or unwashed food, may contribute to the progress of ulcerative colitis.

CONCLUSION

Both gender-related and city- and countryside-related differences were found in the expression of ulcerative colitis in the Chinese population. Lifestyle factors such as psychological stress and fatigue may contribute to the expression of ulcerative colitis.