Overweight and obesity are major risk factors for many chronic diseases, with the prevalence of overweight/obesity among Chinese adults reaching 50.7% in 2018. Bariatric surgery is one currently available treatment for obesity, but whether it increases the risk of fracture is still controversial.

To analyze whether weight-loss surgery will increase the risk of fracture.

PubMed, Embase, and Cochrane Library databases were searched for studies (cohort studies, case-control studies, and randomized controlled trial) about the risk of fracture and bariatric surgery published between January 2010 and November 2021. The Newcastle-Ottawa scale (NOS) and Jadad scale were used to evaluate the methodological quality of the studies. RevMan 5.3 and Stata 12.0 were used for data analysis. The Begg's test and Egger's test were conducted to assessing the potential publication bias. Compare the association of bariatric surgery with risk of fracture by comparing risk of fracture between patients with and without bariatric surgery.

A total of 15 studies were included, including 12 cohort studies, two case-control studies, and one randomized controlled trial, all of which were of high quality. Twelve studies compared the risk of fracture between patients with bariatric surgery and those without, 10 of which enrolled patients with bariatric surgery (surgery group, n=137 239) and obese patients without bariatric surgery (obesity group, n=159 066) with no differences in baseline BMI, showing large heterogeneity (P<0.01, I²=94%). Meta-analysis using a random-effects model showed that there was no significant intergroup difference in fracture risk between the two groups〔RR (95%CI) =1.21 (1.00, 1.46), P=0.05〕. Four studies enrolled patients with bariatric surgery (n=14 796) and non-obese patients without bariatric surgery (n=132 124) with significant differences in baseline BMI, showing slight heterogeneity (P=0.26, I²=25%), and a higher risk of fracture was found in those with bariatric surgery revealed by meta-analysis using a fixed effects model〔RR (95%CI) =1.73 (1.59, 1.89), P<0.01〕. The level of heterogeneity decreased significantly after removing 4 of the 10 studies with high heterogeneity with no intergroup difference in baseline BMI (P=0.24, I²=25%), and a higher risk of fracture was found in patients with bariatric surgery indicated by meta-analysis using a fixed effects model〔RR (95%CI) =1.38 (1.31, 1.46), P<0.01〕. Subgroup analysis showed that the risk of fracture was similar in the surgery group and the obesity group within two years〔RR (95%CI) =1.05 (0.89, 1.24), P=0.56〕 and during two to five years〔RR (95%CI) =1.16 (1.00, 1.35), P=0.05〕, but it was higher in the former group five years after surgery〔RR (95%CI) =1.50 (1.23, 1.84), P<0.001〕. The risk of fracture was higher in patients with Roux-en-Y gastric bypass than that of those with adjustable gastric banding〔RR (95%CI) =1.31 (1.15, 1.50), P<0.01〕 or with sleeve gastrectomy〔RR (95%CI) =1.77 (1.55, 2.02), P<0.01〕. The risk of fracture was lower in patients with gastric banding than that of those with gastric bypass〔RR (95%CI) =0.54 (0.41, 0.71), P<0.01〕. Both Begg's test and Egger's test showed that publication bias was less likely in the studies (P=0.631, 0.720) .

Fracture risk is increased by bariatric surgery, which is not influenced by obesity. High risk of fracture did not appear until five years after the operation, with Roux-en-Y gastric bypass and gastric bypass were associated with higher fracture risk.