Change in fracture risk and fracture pattern after bariatric surgery: nested case-control study.
OBJECTIVE
To investigate whether bariatric surgery increases the risk of fracture.


METHODS
Retrospective nested case-control study.


METHODS
Patients who underwent bariatric surgery in the province of Quebec, Canada, between 2001 and 2014, selected using healthcare administrative databases.


METHODS
12 676 patients who underwent bariatric surgery, age and sex matched with 38 028 obese and 126 760 non-obese controls.


METHODS
Incidence and sites of fracture in patients who had undergone bariatric surgery compared with obese and non-obese controls. Fracture risk was also compared before and after surgery (index date) within each group and by type of surgery from 2006 to 2014. Multivariate conditional Poisson regression models were adjusted for fracture history, number of comorbidities, sociomaterial deprivation, and area of residence.


RESULTS
Before surgery, patients undergoing bariatric surgery (9169 (72.3%) women; mean age 42 (SD 11) years) were more likely to fracture (1326; 10.5%) than were obese (3065; 8.1%) or non-obese (8329; 6.6%) controls. A mean of 4.4 years after surgery, bariatric patients were more susceptible to fracture (514; 4.1%) than were obese (1013; 2.7%) and non-obese (3008; 2.4%) controls. Postoperative adjusted fracture risk was higher in the bariatric group than in the obese (relative risk 1.38, 95% confidence interval 1.23 to 1.55) and non-obese (1.44, 1.29 to 1.59) groups. Before surgery, the risk of distal lower limb fracture was higher, upper limb fracture risk was lower, and risk of clinical spine, hip, femur, or pelvic fractures was similar in the bariatric and obese groups compared with the non-obese group. After surgery, risk of distal lower limb fracture decreased (relative risk 0.66, 0.56 to 0.78), whereas risk of upper limb (1.64, 1.40 to 1.93), clinical spine (1.78, 1.08 to 2.93), pelvic, hip, or femur (2.52, 1.78 to 3.59) fractures increased. The increase in risk of fracture reached significance only for biliopancreatic diversion.


CONCLUSIONS
Patients undergoing bariatric surgery were more likely to have fractures than were obese or non-obese controls, and this risk remained higher after surgery. Fracture risk was site specific, changing from a pattern associated with obesity to a pattern typical of osteoporosis after surgery. Only biliopancreatic diversion was clearly associated with fracture risk; however, results for Roux-en-Y gastric bypass and sleeve gastrectomy remain inconclusive. Fracture risk assessment and management should be part of bariatric care.
Endocrinology and Nephrology Unit, CHU de Québec Research Centre, Quebec City, Canada, G1V 4G2.|Department of Medicine, Laval University, Quebec City, Canada, G1V 0A6.
Catherine
C
Rousseau
Department of Medicine, Laval University, Quebec City, Canada, G1V 0A6.|Institut national de santé publique du Québec, Quebec City, Canada, G1V 5B3.
Sonia
S
Jean
Institut national de santé publique du Québec, Quebec City, Canada, G1V 5B3.
Philippe
P
Gamache
Quebec Heart and Lung Institute - Laval University, Quebec City, Canada, G1V 4G5.
Stéfane
S
Lebel
Endocrinology and Nephrology Unit, CHU de Québec Research Centre, Quebec City, Canada, G1V 4G2.|Department of Medicine, Laval University, Quebec City, Canada, G1V 0A6.
Fabrice
F
Mac-Way
Quebec Heart and Lung Institute - Laval University, Quebec City, Canada, G1V 4G5.
Laurent
L
Biertho
Endocrinology and Nephrology Unit, CHU de Québec Research Centre, Quebec City, Canada, G1V 4G2.|Department of Medicine, Laval University, Quebec City, Canada, G1V 0A6.
Laëtitia
L
Michou
Endocrinology and Nephrology Unit, CHU de Québec Research Centre, Quebec City, Canada, G1V 4G2 claudia.gagnon@crchudequebec.ulaval.ca.|Department of Medicine, Laval University, Quebec City, Canada, G1V 0A6.|Institute of Nutrition and Functional Foods, Quebec City, Canada, G1V 0A6.
Claudia
C
Gagnon
D000328:Adult; D050110:Bariatric Surgery / Q000009:adverse effects* / Q000379:methods; D016022:Case-Control Studies; D005260:Female; D050723:Fractures, Bone / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000150:complications* / Q000601:surgery; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology; D011184:Postoperative Period; D057234:Preoperative Period; D011792:Quebec / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors