Study Overview
Objective. To identify the long-term outcomes of bariatric surgery in adults with severe obesity.
Design. Prospective longitudinal observational cohort study (the Longitudinal Assessment of Bariatric Surgery Consortium [LABS]). LABS was established to collect long-term data on safety and efficacy of bariatric surgeries.
Participants and setting. 2458 patients who underwent Roux-en-Y gastric bypass (RYGB) or laparoscopic adjustable gastric banding (LAGB) at 10 hospitals in 6 clinical centers in the United States. Participants were included if they had a body mass index (BMI) greater than 35 kg/m 2 , were over the age of 18 years, and had not undergone prior bariatric surgeries. Participants were recruited between 2006 and 2009, and follow-up continued until September 2012. Data collection occurred at baseline prior to surgery and then at 6 months, 12 months, and annually until 3 years following surgery.
Main outcomes measures. 3-year change in weight and resolution of diabetes, hypertension, and dyslipidemia.
Main results. Participants were between the ages of 18 and 78 years. The majority of participants were female (79%) and white (86%). Median BMI was 45.9 (interquartile range [IQR], 41.7–51.5). At baseline, 774 (33%) had diabetes, 1252 (63%) had dyslipidemia, and 1601 (68%) had hypertension. Three years after surgery, the LAGB group exhibited greater weight loss (median 41 kg vs. 20 kg). Participants experienced most of their total weight loss during the first year following surgery. As for the health parameters assessed, at 3 years 67.5% of RYGB patients and 28.6% of LAGB patients had at least partial diabetes remission, 61.9% of RYGB patients and 27.1% of LAGB patients had dyslipidemia remission, and 38.2% of RYGB patients and 17.4 % of LAGB patients had hypertension remission.
Conclusion. Three years following bariatric surgery, participants with severe obesity exhibited significant weight loss. There was variability in the amount of weight loss and in resolution of diabetes, hypertension and dyslipidemia observed.
Commentary
Obesity in the United States increased threefold between 1950 and 2000 [1]. Currently, more than one-third of adult Americans are obese [2]. The relationship between obesity and risk for morbidity from type 2 diabetes, hypertension, stroke, sleep apnea, osteoarthritis, and several cancers is well documented [3]. Finkelstein et al [4] estimated that health care costs related to obesity and consequent morbidity were approximately $148 billion in 2008. The use of bariatric surgery to address obesity has grown in recent years. However, there is a dearth of knowledge regarding the long-term outcomes of these procedures.
In this study of RYGB and LAGB patients, 5 weight change patterns were identified in each group for a total of 10 trajectories. Although most weight loss was observed during the first year following surgery, 76% of RYGB patients had continued weight loss for 2 years with a small weight increase the subsequent year. Only 4% of LAGB patients experienced consistent weight loss after 3 years. Overall, participants who underwent LAGB had greater variability in outcomes than RYGB patients. RYGB patients experienced greater remission of all chronic conditions examined and fewer new diagnoses of hypertension and dyslipidemia. The RYGB group experienced 3 deaths occurring within 30 days post-surgery while the LAGB group had none.
This study has several strengths, including its longitudinal design and the generalizability of study findings. Several factors contribute to the generalizability, including the large sample size (n = 2458), which includes participants from 10 hospitals in 6 clinical centers and was more diverse than prior longitudinal studies of patients following bariatric surgery. In addition, the study had clear inclusion criteria, and attrition rates were low; data were collected for 79% and 85% of the RYGB and LAGB patients, respectively. Additionally, study personnel were trained on data collection, which occurred at several time-points.
There are also a few limitations, including that researchers used several methods for collecting data on associated physical and physiologic indicators. Most weights were collected using a standardized scale; however, weights recorded on other scales and self-reported weights were collected if an in-person weight was not obtained. Similarly, different measures were used to identify chronic conditions. Diabetes was identified by 3 different measures: taking a diabetes medication, glycated hemoglobin of 6.5% or greater, and fasting plasma glucose of 126 mg/dL or greater. Hypertension was defined as either taking an antihypertensive medication, elevated systolic (≥ 140 mm Hg) or elevated diastolic blood pressure (≥ 90 mm Hg). Likewise, high low-density lipoprotein (≥ 160 mg/dL ) and taking a lipid-lowering medication were used as indicators of hyperlipidemia. Therefore, chronic conditions were not identified or measured in a uniform manner. Accordingly, the authors observed high variability in remission rates among participants in the LAGB group, which may be directly attributed to the inconsistencies in identification of disease status. Although the sample is identified as diverse compared with similar studies, it primarily consisted of white females.
A significant finding was that non-white and younger participants had more missing data, as they were less likely to return for follow-up visits. Additionally, large discrepancies in weight loss were noted. Authors assert that both these findings suggest more education and support are needed for lasting adherence in some subgroups of patients undergoing bariatric surgery. Further evaluation of which factors contribute to these differences in weight loss is also needed.
Applications for Clinical Practice
This study is relevant to practitioners caring for patients with multiple chronic conditions related to severe obesity. The results indicate that bariatric surgery is associated with significant improvements in weight and remission of several chronic conditions. Practitioners can inform patients about the safety and efficacy of bariatric surgery procedures and discuss the evidence supporting its long-term efficacy as an intervention. As obesity rates continue to increase, it is important to understand the long-term benefits and risks of bariatric surgery.
—Billy A. Caceres, MSN, RN, and Allison Squires, PhD, RN