P446 Influence of seasonal vitamin D deficit in clinical course of inflammatory bowel disease patients

Abstract

Abstract Background Vitamin D deficiency is common in healthy subjects and it is even more prevalent in inflammatory bowel disease (IBD). Vitamin D (VitD) may influence disease behavior. Whether a deficient vitamin D status facilitates flares or flares consume vitamin D is still a burning question. Data on seasonal variations of VitD levels in IBD are scarce. The aim of this study was to evaluate VitD deficit in IBD patients compared with general population and the influence of seasonal variation in their evolution. Methods A prospective two center study was performed. Patients with Crohn disease (CD) or ulcerative colitis (UC) and no comorbilities that may have influenced VitD were consecutively included from two IBD centers with geographical proximity (less than 100 kms) in order to have comparable solar radiation. Clinical and biochemical characteristics of patients were recorded. Patients were followed for two consecutive seasons, VitD was measured twice: during winter and during summer. VitD levels from general population were also available. Both hospitals share the same methodology for VitD testing. VitD levels were defined as normal (>30 ng/ml), insufficient (20-30 ng/ml), or deficient (<20 ng/ml). Data were analyzed and Mann-Whitney U test was applied using R to compare subsets of patients. Results 199 patients with IBD were consecutively included (38.7% CD, 61.3% UC). 165 (83%) patients have consecutive determinations of VitD (both in summer and winter). Mean age was 47.1, being 54.8% males and 45.2% females. Median value of VitD in winter was 14 ng/ml, and 21 ng/ml in summer. Lab tests in our center for general population in winter presented a median value was 21.2 ng/ml in winter and 24 ng/ml in summer (Figure 1). According values of our laboratory in winter, just 31% of the general population presented VitD values > 30 ng/ml in summer and 26.7% do so in winter. For our cohort of patients with IBD, the results are more pronounced: only 3.8% presented normal values in winter and 23.2% in summer (Table 1). The average variation in VitD values has been 9.26 ng/ml between the two seasons. No statistically significant relationship was found between the factors analyzed (BMI, location, calprotectin levels or disease duration) and VitD levels, neither in summer nor in winter. Most patients remained in remission despite having low VitD levels (82,8% in winter and 80,3% in summer). Conclusion VitD deficit was frequent in summer and in winter in IBD and more prevalent than in general population. Despite frequent deficit only a small percentage of patients presented disease activity. No relationship was observed between VitD deficit and patients characteristics or calprotectin levels.