- Click here for explanation of classification scheme.

The purpose of this review study was to analyze the effect of bariatric surgery on chronic diseases (diabetes, hyperlipidemia, hypertension and obstructive sleep apnea), disease risk, cost of healthcare, weight loss and mortality.

Researchers selected articles that dealt with at least one of the following categories: Surgical outcomes (e.g., efficacy and/or safety), guidelines, cost of healthcare and disease risk.

Abstracts were excluded if they met any of the following criteria:

• Publication of only abstracts, case reports, letter, comments and reviews
• Animal or in vitro studies
• Fewer than 10 patients in the study
• Follow-up occurred less than 30 days
• Languages other than English
• No surgical treatment of obesity
• Use of intragastric balloon therapy.

Design

Included articles had to pass two levels of screening. For articles to be included in data extraction analysis, screened studies had to report outcomes for one or more of the following comorbidities: Diabetes, hyperlipidemia, hypertension and obstructive sleep apnea. Extracted designs could be of any design, but must have been published between 1990 and 2003.

This meta-analysis investigated weight loss differences among patients who underwent gastric banding, gastric bypass, gastroplasty and biliopancreatic diversion (or duodenal switch).

Statistical Analysis

Analysis was performed only on studies from which data were extracted. Study, patient and treatment-level data were summarized using basic descriptive statistics. The number of patients enrolled or randomized was used in the calculation of study and patient demographics.

Meta-analysis within-study surgery effects on weight loss and diabetes-related outcomes were stratified by studies with extractable outcomes for a general population compared with subgroups of patients with diabetes or impaired glucose intolerance. Meta-analysis of all efficacy outcomes were conducted using a random-effects model, estimated by using the restricted maximum likelihood method. The random-effects model meta-analyses consider both study sample size and the estimate of between-study variation when weighing study effects. Meta-analysis means and mean changes are expressed with 95% confidence intervals.

All calculations were performed using SAS and SPSS statistical software.

Variables Measured

• Weight loss: Outcomes were preferentially extracted at time points for which comorbidity changes were reported
• Operative mortality: Mortality at 30 days or less
• Comorbidity outcomes: Diabetes, hyperlipidemia, hypertension and obstructive sleep apnea.

Interventions

Patients in reviewed studies underwent one of the following weight loss surgeries:

• Gastric banding
• Gastric bypass
• Gastroplasty
• Biliopancreatic diversion or duodenal switch.

 

Initial N

134 studies were extracted [of studies reporting gender (150 treatment groups), 19.4% (N=3,769) were men, 72.6% (N=14,082) were women]. Gender was not reported for 8% (1,537) of patients.

Age

Overall mean age was 38.97 years (range 16.20 years to 63.60 years).

Ethnicity

Of studies extracted, 56 were based in North America, 58 in Europe and 20 in other locations (Australia, New Zealand, South America, Japan, Israel, Saudi Arabia and Taiwan). Ethnicity of patients was not described.

Anthropometrics

Mean body mass index (BMI) for 16,944 patients at baseline was 46.85kg/m² (range 32.30kg/m² to 68.60kg/m²).

Other Relevant Demographics

Mean age and BMI were relatively similar across surgical procedure types.

Location

University of Minnesota, Minneapolis, MN (location of lead author).

 

 

Outcome	N=Patients (Treatment Group)	Mean Change in Body Weight in kg (Range)	Weighted Mean Change (Range)
Absolute weight loss (kg)	7,588 (83)	-39.71 (-42.23 to -37.19)	-40.53 (-70 to -9.0)
Body mass index (BMI) decrease (kg/m2)	8,232 (96)	-14.20 (-15.13 to -13.27)	-14.01 (-27.0 to -4.10)
Initial weight loss (%)	1,386 (9)	-32.64 (-36.39 to -28.89)	-35.58 (-39.0 to -20.90)
Percent excess weight loss (%)	10,172 (67)	-61.23 (-64.4 to -58.06)	-64.67 (-93.0 to -32.0)

Other Findings

• Patients who underwent biliopancreatic diversion or duodenal switch experienced a greater percentage excess weight loss (-70.12%) as compared to patients who underwent gastroplasty (-68.17%), gastric bypass (-61.56%) or gastric banding (-47.45%)
• Diabetes was completely resolved in 76.8% of patients and resolved or improved 86.0%
• Hyperlipidemia improved in 70% or more of patients
• Hypertension was resolved in 61.7% of patients and resolved or improved in 78.5%
• Obstructive sleep apnea was resolved in 85.7% of patients and was resolved or improved in 83.6% of patients.

 

The author concludes that patients undergoing bariatric surgical procedures lose weight and tend to completely resolve or improve diabetes, hyperlipidemia, hypertension and obstructive sleep apnea.