Comparing the Benefits and Harms of Three Types of Weight Loss Surgery -- The PCORnet® Bariatric Study

National Patient-Centered Clinical Research Network (PCORnet) Bariatric Study

The main goal of this research project is to conduct a comparative effectiveness research study involving existing data in the PCORnet Common Data Model to provide accurate estimates of the 1-, 3-, and 5-year benefits and risks of the three most common bariatric procedures - Roux-en-y gastric bypass, adjustable gastric banding, and sleeve gastrectomy - with a focus on outcomes that are important to adults and adolescents with severe obesity: 1) changes in weight, 2) rates of remission and relapse of diabetes, and 3) major adverse events.

The main aims of this study will compare the effectiveness and safety of the three most common bariatric surgical procedures: Roux-en-y gastric bypass (RYGB), adjustable gastric banding (AGB), and sleeve gastrectomy (SG).

Question (Aim) 1: To what extent does weight loss and weight regain differ across the three bariatric surgical procedures at 1, 3, and 5 years? This aim addresses the primary outcome of interest among most patients seeking bariatric surgery - the differential impact of these procedures on maximum weight loss as well as the extent of longer-term weight regain. We will also explore the heterogeneity in weight loss and regain across several key subgroups that may have differential response to surgical treatment, specifically groups defined by age, race/ethnicity, baseline BMI, smoking status, and pre-operative comorbidities.

Question (Aim) 2: To what extent do these bariatric procedures differ on improvements in diabetes risk at 1, 3, and 5 years? Among patients with diabetes, remission or "cure" of their disease (defined as HbA1c <6.5% off diabetes medications) has been cited as the most important outcome of bariatric surgery. Thus, we will examine the comparative effect of these procedures on rates of diabetes remission as well as relapse (recurrence). Secondary analyses will examine the comparative impact of the procedures on glycemic control independent of diabetes remission.

Question (Aim) 3: What is the frequency of major adverse events following these three different bariatric surgical procedures at 1, 3, and 5 years? We will examine four important adverse event outcome categories across the three procedures: 1) short- and long-term (1, 3, and 5 year) mortality rates, 2) a composite end point of 30-day major adverse outcomes: based on the definition used in the Longitudinal Assessment of Bariatric Surgery (LABS) study that included death; venous thromboembolism; percutaneous, endoscopic, or operative subsequent intervention; and failure to be discharged from the hospital; 3) subsequent hospitalization (any hospitalization following initial surgery); and 4) subsequent reoperation/reintervention: defined as any additional bariatric procedure and other procedures related to device removals, gastric revisions, abdominal or incisional hernia repair, laparoscopy or laparotomy, and percutaneous endoscopic gastrostomy tube placements.

Question (Aim) 4: To what extent do bariatric surgery outcomes explored in Aims 1-3 differ with respect to baseline depression diagnosis at 1, 3, and 5 years after surgery?

Question (Aim) 5: To what extent do bariatric surgery outcomes explored in Aims 1-3 differ with respect to race and ethnicity at 1, 3, and 5 years after surgery?

ALL STUDY AIMS

• Inclusion Criteria:

  • Adults and children ages 12 ≤79 years at time of surgery

  • Had a primary (not revision) bariatric procedure from years 2005-2015 of one of three types:

    1. Roux-en-y gastric bypass (RYGB)
    2. Adjustable gastric banding (AGB)
    3. Sleeve gastrectomy (SG)

  • Have a Body Mass Index (BMI) measurement in the year prior to surgery that is ≥35 kg/m2

• Exclusion Criteria:

  • First bariatric procedure during the study period is a revision procedure, a vertical banded gastroplasty procedure or Biliopancreatic Diversion Procedure
  • Have multiple bariatric procedures coded on the same day
  • Have a diagnosis related to GI cancer occurring on day of surgery or during index hospitalization (Diagnosis determined using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)
  • Emergency department visit on the same day as hospitalization for bariatric procedure

ADDITIONAL INCLUSION CRITERIA FOR AIM 2 (Diabetes)

• Eligible patients must have uncontrolled or medication-controlled diabetes at the time of surgery.

• Hemoglobin A1c (HbA1c) ≥6.5 % at the most recent measurement prior to surgery, or
• Current prescription for diabetes medication at the time of surgery with the most recent HbA1c <6.5% Patients taking only metformin will be excluded unless they also have an ICD-9-CM code for Diabetes (250.x) or have HbA1c >=6.5% in the year prior to surgery. This includes patients with polycystic ovarian syndrome (PCOS).

ADDITIONAL INCLUSION CRITERIA FOR AIM 3 (Adverse Events)

• Eligible patients must be linked to relevant data sources:

  • State or national death index (mortality outcomes);
  • Payer data/insurance claims (for Adverse Events outcomes)

• Patients must be aged 20 through 79 years of age at time of surgery.

ADDITIONAL EXCLUSION CRITIERA FOR AIM 3 (Adverse Events)

• Exclude any patient with >=365 inpatient hospitalization days in the year prior to surgery.
• Exclude any patient without male or female sex indicated in the study data

AIM 4 (Surgery Outcomes and Baseline Depression) and AIM 5 (Surgery Outcomes and Race/Ethnicity): Inclusion criteria for Aims 1, 2, and 3 will be used for the outcomes from these aims.

ADDITIONAL INCLUSION CRITERIA FOR AIM 5 (Surgery Outcomes and Race/Ethnicity)

• Race and ethnicity available in study data