SAT-117 Prevalence of Vitamin D Depletion and Associated Factors among Patients Undergoing Bariatric Surgery in Southern Brazil

Low levels of 25(OH) vitamin D [25(OH)D] are frequent in obese patients undergoing bariatric surgery. Hypovitaminosis D is a concern in these patients, since it could contribute to the bone loss seen after surgery, and potentially increase fracture risk . Despite post-operative supplementation, 25(OH)D often remains below recommended levels following surgery. Guidelines recommend that vitamin D levels are determined preoperatively. Nevertheless, the systematic determination of 25(OH)D in thousands of patients every year is costly. The prevalence of low levels of 25(OH)D seems to be high among Southern Brazilians. In this scenario, it may be unnecessary to check blood levels prior to introduction of supplementation in bariatric patients. The aim of this study was to evaluate the prevalence of vitamin D deficiency and associated factors in patients undergoing bariatric surgery in Southern Brazil. This was a Cross-sectional, observational study of all patients presenting for bariatric surgery at Hospital de Clínicas de Porto Alegre (a teaching hospital), from 2013 to 2018. Clinical and laboratory data were extracted from electronic records. Patients who were taking supplements containing vitamin D, had renal insufficiency or had missing data for 25(OH)D levels were excluded. Vitamin D status was determined using established cut-offs (deficient ≤19.9 ng/ml; insufficient 20-29.9 ng/mL; sufficient ≥30 ng/mL). Factors associated with vitamin D deficiency were analysed by univariate and multivariable robust Poisson Regression. 297 patients met the inclusion criteria. Mean patient age was 44.7(SD 10.8), and BMI 49,9(SD 8.1) kg/m²; 77.1% were women, and 87.5% were white. More than half the patients (54.5%) were vitamin D deficient, whereas 37% were insufficient, and only 8.4 % had sufficient levels. Mean vitamin D level was 19.7 ng/mL(SD 7.7). Vitamin D deficiency was significantly more prevalent in patients with higher BMI [PR 1.02; CI 95% (1.00-1.03)] and in nonwhite patients [PR 1.71; CI 95% (1.43-2.04)]. Vitamin D insufficiency and deficiency is highly prevalent among patients presenting for bariatric surgery in Southern Brazil. These results are in accordance with studies in Europe and North America. Although sunnier and located in a smaller latitude, Brazil has no food fortification policy and the average vitamin D dietary intake is below the recommendation in almost 100% of its population. Thus, treatment for hypovitaminosis D might routinely be considered in bariatric surgery candidates, especially in those with characteristics identified as independent risk factors for vitamin D deficiency, such as higher BMI and being non-white. Long-term studies are required to assess the eventual advantages and side effects of systematic vitamin D supplementation in this population.