IMPORTANCE Perception of weight loss requirements before bariatric surgery varies among patients, physicians, and health insurance payers. Current clinical guidelines do not require preoperative weight loss because of a lack of scientific support regarding its benefits. OBJECTIVE To examine the association of preoperative body mass index (BMI) and weight loss with 30-day mortality after bariatric surgery. DESIGN, SETTING, AND PARTICIPANTS This cohort study used data from 480 075 patients who underwent bariatric surgery from 2015 to 2017 in the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program, which covers more than 90% of all bariatric surgery programs in the United States and Canada. Clinical and demographic data were collected at all participating institutions using a standardized protocol. Data analysis was performed from December 2018 to November 2019. EXPOSURES Preoperative BMI and weight loss. MAIN OUTCOMES AND MEASURES 30-day mortality after bariatric surgery. RESULTS Of the 480 075 patients (mean [SD] age 45.1 [12.0] years; 383 265 [79.8%] women), 511 deaths (0.1%) occurred within 30 days of bariatric surgery. Compared with patients with apreoperative BMI of 35.0 to 39.9, the multivariable-adjusted odds ratios for 30-day mortality for patients with preoperative BMI of 40.0 to 44.9, 45.0 to 49.9, 50.0 to 54.9, and 55.0 and greater were 1.37 (95% CI, 1.02-1.83), 2.19 (95% CI, 1.64-2.92), 2.61 (95% CI, 1.90-3.58), and 5.03 (95% CI, 3.78-6.68), respectively (P for trend < .001). Moreover, compared with no preoperative weight loss, the multivariable-adjusted odds ratios for 30-day mortality for patients with weight loss of more than 0% to less than 5.0%, 5.0% to 9.9%, and 10.0% and greater were 0.76 (95% CI, 0.60-0.96), 0.69 (95% CI, 0.53-0.90), and 0.58 (95% CI, 0.41-0.82), respectively (P for trend = .003). CONCLUSIONS AND RELEVANCEIn this study, even moderate weight loss (ie, >0% to <5%) before bariatric surgery was associated with a lower risk of 30-day mortality. These findings may help inform future updates of clinical guidelines regarding bariatric surgery.

Fetuin-A is a multifunctional protein which inhibits ectopic calcification and insulin receptor phosphorylation. It may also promote insulin resistance by activation of toll-like receptor 4 pro-inflammatory cascade. Increased levels of Fetuin-A have been associated with obesity and related comorbidities such as type 2 diabetes and cardiovascular disease, therefore, it has been suggested as a potential therapeutic target for intervention. However, in addition to its role in disease pathophysiology, Fetuin-A is also important for growth and development. Thus, before evaluating Fetuin-A as a biomarker or pharmacological target, an understanding of Fetuin-A variability throughout the life cycle is essential. This manuscript reviews the current body of knowledge surrounding Fetuin-A throughout the life cycle and discuss challenges to studying Fetuin-A.

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