When traditional approaches for weight loss, such as diet, exercise, and medications, fail as effective treatments for obesity, bariatric surgical procedures that restrict stomach size or lead to altered absorption of nutrients may be performed. While these procedures often result in significant, sustained weight loss, the benefits must be balanced against the short- and long-term risks of bariatric surgery. The Longitudinal Assessment of Bariatric Surgery (LABS) observational study was established to assess the risks and health benefits associated with bariatric surgery and to identify aspects of the procedures and patient characteristics associated with optimal outcomes. The study was organized into three phases: LABS-1, which evaluated the short-term safety of bariatric surgery; LABS-2, which evaluated the longer-term safety and efficacy of bariatric surgery, and examined patient characteristics associated with short- and intermediate-term outcomes; and LABS-3, which examined psychosocial, quality of life, and health economics aspects of obesity and the mechanisms of obesity-related diseases.

The LABS-1 study enrolled participants at least 18 years of age who underwent bariatric surgical procedures between March 2005 and December 2007 at LABS surgical centers. Participants underwent a pre-operative evaluation, during which data was collected on height, weight, blood pressure, comorbid conditions, and physical examination. Participant outcomes were recorded post-operatively.

An ancillary study from LABS-1 regarding psychosocial issues associated with weight loss was conducted at two of the LABS study centers, and a set of control participants were recruited from primary care practices outside of the LABS consortium. The overall duration of the ancillary study was 48 months with the goal of assessing changes in sexual function and sex hormones in the two groups at predetermined follow-up visits.

An ancillary study from LABS-1 regarding cognitive effects of bariatric surgery was conducted at two of the LABS study centers, and a set of control participants were recruited who did not plan to have bariatric surgery for at least two years. The overall duration of the ancillary study was 24 months with a subset of participants providing additional follow-up for 48 months.

Both the ancillary studies and full data for LABS-1 are available in the data package.

The primary objectives of the LABS-1 study was to assess the safety of bariatric surgery by estimating the prevalence of short term adverse outcomes in a multicenter cohort of participants undergoing bariatric surgical procedures, and to determine the associations between short term adverse outcomes after bariatric surgery and both clinical/demographic participant characteristics and features of operative/perioperative care.

The primary outcome measure was a composite endpoint of any of the following occurring within 30 days of surgery: death; deep vein thrombosis (DVT) or venous thromboembolism (VTE); reintervention using percutaneous, endoscopic, or operative techniques; or failure to discharge from the hospital.

Participants at least 18 years of age who undergo bariatric surgery by a LABS certified surgeon.

Informed consent not obtained.

Of the 4,776 participants enrolled in the LABS-1 study who had a first-time procedure, over half had at least two co-morbid conditions. The 30-day mortality rate for Roux-en-Y gastric bypass or laparoscopic adjustable gastric banding was 0.3%, and 4.3% of participants had at least one major adverse outcome. The LABS-1 study showed that the short-term risk of death and adverse outcome after bariatric surgery was low, particularly when contrasted with participant characteristics.

The ancillary study found that for men enrolled that had bariatric surgery and lost one-third of their weight had experienced a significant increase in total testosterone, but no improvements in sexual function or relationship satisfaction. For women enrolled that had bariatric surgery, there were significant improvements in sexual functioning, sex hormones, and overall psychosocial status.