FRI0377 BARIATRIC SURGERY: EFFECTS ON BONE METABOLISM

Background: There are few data about variations in bone metabolism associated with weight loss in obese patients undergoing bariatric surgery. Objectives: To assess the influence on the bone metabolism of bariatric surgery in morbidly obese patients. Methods: Longitudinal pre-post study with analytical components. All morbidly obese patients undergoing bariatric surgery were, prior to this, referred to Rheumatology Department. In all cases, the baseline characteristics of the patients were collected and a complete bone metabolic analytical study and bone densitometry (BMD) were requested. This same study was repeated one year later, with a window period of ± 3 months. Statistical analysis was performed with the SPSS 20.0 software. Results: Of the 91 patients included in the study and who underwent baseline BMD and analytical tests prior to surgery, only follow-up data of 27 patients could be collected at the time of the present data analysis. Within this sample, the median age was 54 years (AIQ 11), with 6 men and 21 women (11 premenopausal, 10 postmenopausal). Prior to surgery, median body mass index (BMI) was 39.2 (AIQ4.43) and median vitamin D (25OHD) level was 22 (AIQ 16). High values of PTH were detected in two patients. Regarding baseline BMD, 78% had normal values and 22% had values in the range of osteopenia. After surgery, all patients presented a significant weight loss, being the median loss in BMI per year 9.8 Kg/m2 (AIQ 3.8) as absolute value, and 25% (AIQ 8.12) as a percentage value. This weight loss was accompanied by a significant BMD worsening that was evident in all locations: lumbar spine (median -6.97%, AIQ 6.3), total hip (median -6.4%, AIQ 7.7) and femoral neck (median -3.57 %, AIQ 8); so that an additional 22% of patients changed to osteopenia values. All this despite a significant increase in 25OHD levels in all cases (35.7%; AIQ 52.3). No clinical or morphometric fractures were collected. Despite the parallel evolutionary course, the loss of BMI only showed a tendency to correlate with the decrease in bone mass in the femoral neck (p-value 0.089), but not in the other locations. Conclusion: In our sample of morbidly obese patients undergoing bariatric surgery, there is a significant and widespread loss of bone mineral density one year after the procedure, all this despite the supplementation and the increase in 25OHD levels. This loss only seems to be directly related to the decrease in weight at the femoral neck, just probably by a mechanism to reduce mechanical load. Disclosure of Interests: I Vazquez-Gomez: None declared, Ramon Trullenque Juan: None declared, Carlos Morillas Arino: None declared, L Montolio-Chiva: None declared, Ana V Orenes Vera: None declared, Eduardo Flores: None declared, Elia Valls-Pascual Grant/research support from: Roche, Novartis, and AbbVie, Speakers bureau: AbbVie, Lilly, Pfizer, MSD, Novartis, Janssen, Bristol Myers Squibb, UCB Pharma, Desamparados Ybanez: None declared, A Martinez-Ferrer: None declared, Inmaculada Torner Hernandez: None declared, V Nunez-Monje: None declared, A Sendra-Garcia: None declared, Juanjo J Alegre-Sancho Consultant of: UCB, Roche, Sanofi, Boehringer, Celltrion, Paid instructor for: GSK, Speakers bureau: MSD, GSK, Lilly, Sanofi, Roche, UCB, Actelion, Pfizer, Abbvie, Novartis