Bone metabolism and fracture risk after Biliopancreatic Diversion

Bariatric surgery (BS) is an effective treatment. However, there have been concerns regarding the negative effect on the bone. The aim of this study was to assess changes in bone metabolism and the risk of fracture after biliopancreatic diversion (BPD).

A retrospective analysis of obese patients undergoing BPD between 1998 and 2017 was conducted, and patients with at least 1 year of follow-up were included. The incidence of fracture and of changes in bone metabolism was studied.

In total, 216 patients were included (78.2% female), with a mean age of 42.5(10.6) years. The median follow-up was 6.8(IQR 10.2-3.2) years. The mean body mass index (BMI) was 49.7(6.3) kg/m². 13.2% (n=29) suffered a bone fracture after surgery; the time until the first fracture was 7.9(3.8) years (55.2% secondary to a casual fall). The rate of fracture incidence was 19.6 per 1000 person-years (95%CI: 1.3-2.7), prevalence was 13.4% (95%CI: 8.9-18.0). The risk of bone fractures seems to increase with longer postoperative evolution time. PTH (pg/ml) levels were significantly higher in patients with fractures (1 year, 98.1 vs. 77.8; 5 years, 162.5 vs. 110.3 p<0.05, adjusted HR 1.10; 95%CI 1.01-1.11). Subjects with a higher %EWL had less risk of fractures after surgery (adjusted HR 0.97; 95%CI 0.94-0.99). Moreover, 25(OH)D levels were lower, and osteocalcin and β-Crosslaps levels were slightly higher (not significant) in patients with fractures.

BPD is related to important changes in bone metabolism, which can lead to an increased risk of bone fractures. Assessing the risk of fractures should be part of BS patient care.