Reduction in Cardiometabolic Disease Risk Following Gastric Bypass Surgery Among Hispanic Adults

Abstract

Background:

The increasing prevalence of US morbid obesity is associated with serious health consequences and high medical costs, particularly among ethnic minority groups. Little information is available on the long-term weight and chronic disease risk reduction effectiveness of bariatric surgery among Hispanics.

Methods:

A retrospective medical chart analysis of 633 Hispanic adults (76% female, mean age at surgery 41.3 years) from Central and South America and the Caribbean who underwent gastric bypass surgery from 2002 to 2010 was conducted. A presurgery and 1-year postsurgery comparative means analysis of weight, body mass index (BMI), and cardiometabolic disease risk factors [systolic (SBP) and diastolic blood pressure (DBP), fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol (TC), and triglycerides (TGs) was performed.

Results:

Mean weight (127–109 kg) and BMI (46.4—39.9 kg/m²) significantly decreased and all cardiometabolic disease risk factors improved from before to 1 year after surgery. Males were significantly more likely than females to show postsurgery improvement in weight (−21.7 kg versus −16.9 kg, P<0.0001), HbA1c (−1.1% versus −0.7%, P=0.02), HDL (3.2 mg/dL versus −0.6 mg/dL, P=0.04), and TGs (−97.2 mg/dL versus −54.5 mg/dL, P=0.006) versus females. Conversely, women were significantly more likely than men to have postsurgery improvements in LDL (−24.5 mg/dL versus −12.7 mg/dL, P=0.04).

Conclusions:

Gastric bypass surgery results in significant weight loss and cardiometabolic disease risk reduction among Hispanic adults 1 year after surgery. These improvements vary by gender. Gastric bypass surgery is an effective treatment option for weight loss and chronic disease risk improvements in Hispanic adults who are not Mexican American.

Introduction

T he prevalence of obese and overweight adults has increased in all US population groups, but certain ethnic minority groups are disproportionately affected. If current trends continue, by 2030 86.3% adults will be overweight and 51.1%, will be obese.¹ This is particularly troubling because many of the chronic health conditions that are directly attributed to obesity disproportionately affect ethnic minority groups. For example, the incidence of cardiovascular disease² and type 2 diabetes³ and their precursor, the metabolic syndrome,⁴ disproportionately affects Hispanics.

Moreover, it has been estimated that from 1990 to 2000 the prevalence of the metabolic syndrome increased 28%, or from approximately 50 million to 64 million adults residing in the United States.³ Recent estimates using the 1999–2006 National Health and Nutrition Examination Survey (NHANES) data show a further increase of 6%, or 68 million cases, that was highest among Mexican Americans.³ The increased prevalence of metabolic syndrome was primarily due to increases in abdominal obesity and high blood pressure. That study concluded that as we continue to see an increase in metabolic syndrome, especially in certain ethnic groups and younger women, there will be a concomitant increase in diabetes with its associated co-morbidities and incremental medical costs. These metabolic syndrome prevalence estimates could also be attributed to a lack of successfully implemented evidence-based effective prevention and treatment options for those who are obese, have metabolic syndrome, or are at high-risk for future cardiometabolic disease.

In recent years, weight loss surgery has become increasingly accepted as an appropriate treatment option for obesity and its related health issues when conventional methods of weight loss fail.^4,5 However, the bariatric surgical literature consists of predominantly non-Hispanic, Caucasian patient samples with very little outcome data available among ethnic minority groups, and non-Mexican-American Hispanics in particular, even though these are the groups most affected by obesity and related co-morbidities.^2
–4 Additionally, in the United States, the Hispanic population is the fastest growing ethnic minority group and expected to be the minority majority within the next two decades.³ Therefore, this study assessed the efficacy of bariatric surgery as a treatment option in a large sample of Hispanic adults who originated predominantly from Central and South America, as well as the Caribbean Basin countries, by examining weight loss and change in cardiometabolic disease risk factors after surgery.

Methods

A retrospective medical chart analysis was conducted of 633 Hispanic adults who originated predominantly from Central and South America and the Caribbean and who underwent gastric bypass surgery in South Florida between 2001 and 2010. Patients were excluded if they were: (1) Not Hispanic; (2) under 20 years old; or (3) had undergone adjustable gastric band or gastric sleeve procedures. The University of Miami Institutional Review Board approved this study.

Demographics (gender, race and ethnicity), weight, body mass index (BMI), co-morbidities [systolic (SBP) and diastolic blood pressure (DBP), plasma glucose, glycated hemoglobin (HbA1c), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and triglycerides (TGs)], and preoperative complications information were collected prior to surgery. Follow-up weight and cardiometabolic disease risk factor data was then collected 12 months postsurgery. All patients who had either adjustable gastric band surgery (n=133) or missing lab or anthropometric data at 1 year (n=715) were eliminated from the analysis.

Anthropometrics

Height and weight measurements were conducted during routine clinical visits by practice nursing staff. Weight was measured to the nearest 0.1 pound using a digital scale with the participants wearing light clothing and no shoes. Height was measured to the nearest 0.5 cm using an Accustat Genentech stadiometer. BMI was calculated as body weight in kilograms divided by height in meters squared (kg/m²).

Cardiometabolic disease risk factors

We used the American Diabetes Association criteria, in which a fasting (≥8 hr but <24 hr) glucose level of 100 mg/dL or higher was considered to be abnormal.⁶

Laboratory assays

All blood samples were collected, processed, stored at −20°C, and shipped to the laboratory for analysis. HbA1c was analyzed by turbidimetric immunoinhibition with commercially available reagents. TC, LDL, HDL, and TGs were analyzed enzymatically with commercially available reagents. Glucose was measured in plasma collected in sodium fluoride tubes by the hexokinase technique, which converts glucose to glucose-6-phosphate (G-6-P). G-6-P is then oxidized by G-6-P dehydrogenase to yield nicotinamide adenine dinucleotide (NAD), which was then measured spectrophotometrically at 340 nm.

Surgery criteria

All patients met National Institutes of Health criteria for bariatric surgery.⁷ Thus, all patients had a BMI >35 kg/m² and at least one existing co-morbidity (e.g., elevated blood pressure, hypercholesterolemia, etc.) or a BMI >40 kg/m². Patients underwent group and individual education with a practice interdisciplinary group about the potential surgical and nonsurgical options, outcomes, complications, and necessary lifestyle changes. All patients underwent presurgery psychological and nutritional evaluation and testing.

Surgical procedure

The laparoscopic approach was used in all but 5 patients. All patients went to the bariatric floor postoperatively and were started on liquids on postoperative day 1. All patients were discharged home on a standard bariatric liquid diet for 1 week.

Statistical analysis

A t-test for independent samples and chi-squared test were used to analyze baseline differences in continuous and categorical demographic variables. To assess longitudinal change in weight and BMI and all cardiometabolic disease risk factors, separate repeated measures linear mixed models were fit using the MIXED procedure in SAS version 9.2 (SAS Institute, Inc., Cary, NC). Age, sex, and surgery type were the co-variates considered for potential inclusion into each model. The interaction between time and sex was also assessed. Statistical tests resulting in a probability of 0.05 or less were considered statistically significant.

Results

The majority of the sample was female (76%) and underwent gastric bypass surgery (91%) versus adjustable gastric band (9%). Mean age at surgery was 41.1 years [standard deviation (SD) 12.5, range 20–73.7 years] for women and 41.8 years for men (SD 11.0, range 20–69.8 years).

For the overall sample, mean BMI significantly decreased from 46.4 kg/m² presurgery to 39.9 kg/m² postsurgery (P<0.001). Similarly, weight significantly decreased from pre- to postsurgery (127–109 kg, P<0.0001). A total of 30 patients (4.7%) had diabetes (glucose >125 mg/dL) presurgery and 7 (1.1%) had diabetes postsurgery (Table 1). A total of 114 (60%) of patients had the metabolic syndrome (≥3 cardiometabolic risk factors present) presurgery and 2 (0.3%) had metabolic syndrome post surgery (data not shown on tables).

Table 1.

Anthropometric Measures and Laboratory Values of 633 Hispanic Patients Pre and Post Gastric Bypass Surgery

Variable ^a	Presurgery Mean (SE) ^b	Postsurgery Mean (SE) ^b
BMI (kg/m²)	46.4 (0.3)	39.9 (0.3)
Weight (kg)	127.0 (0.9)	109.0 (0.8)
Systolic blood pressure (mm Hg)	134.4 (0.6)	119.8 (1.1)
Diastolic blood pressure (mm Hg)	86.3 (1.3)	74.7 (1.3)
Glucose (mg/dL)^c	99.7 (1.8)	89.9 (1.3)
HbA1c (%)	6.4 (0.9)	5.5 (0.4)
Total cholesterol (mg/dL)	195.0 (2.6)	159.2 (1.7)
HDL-C (mg/dL)	48.3 (0.9)	48.8 (0.6)
LDL-C (mg/dL)	111.8 (2.4)	89.8 (1.8)
Triglyceride (mg/dL)	168.4 (6.1)	102.4 (2.3)

All pre–post surgical differences were statistically significant (P<0.001), except HDL-C.

Means were adjusted by age and gender.

A total of 30 patients (4.7%) had diabetes (glucose >125 mg/dL) presurgery and 7 (1.1%) had diabetes postsurgery.

SE, standard error; BMI, body mass index; HbA1c, glycated hemoglobin; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol.

For the entire sample, all cardiometabolic disease risk factors, with the exception of HDL-C, significantly improved during the same time period as well (P<0.001 for all pre–post comparisons). HDL increased slightly from 48.3 to 48.6 mg/dL, but did not reach statistical significance (Table 1).

Similar weight and cardiometabolic improvements were seen when the sample was stratified by gender, but males were significantly more likely to show postsurgery improvement in weight, HbA1c, HDL-C, and TGs. Men were also more likely to show improvement in fasting plasma glucose and DBP versus women, but these differences were not statistically significant. Conversely, women were significantly more likely than men to have postsurgery improvements in LDL-C. Women were also more likely to have improvements in SBP and TC versus men but these differences were not statistically significant (Table 2).

Table 2.

Changes in Anthropometric Measures and Laboratory Values from Before to 1 Year After Bariatric Surgery Among 633 Hispanic Patients by Gender

	Male			Female
	n=152 (24%)			n=481 (76%)
Variable^a	Presurgery mean (SE)	Postsurgery mean (SE)	% Change	Presurgery mean (SE)	Postsurgery mean (SE)	% Change	Gender group difference P value
BMI (kg/m²)	48.9 (0.8)	41.9 (0.7)	14.3	45.7 (0.3)	41.9 (0.7)	8.3	0.07
Weight (kg)	151.7 (2.4)	130.0 (2.3)	14.3	119.2 (0.8)	102.3 (0.8)	14.2	<0.0001
Systolic Blood Pressure (mmHg)	138.4 (1.3)	126.0 (1.8)	9.0	133.0 (0.7)	119.5 (2.2)	10.0	0.70
Diastolic Blood Pressure (mmHg)	87.0 (1.0)	76.9 (3.9)	11.6	86.1 (1.9)	78.1 (3.3)	9.3	0.68
Glucose (mg/dL)	106.1 (4.5)	91.5 (2.9)	13.8	97.7 (1.9)	89.3 (1.5)	8.6	0.19
HbA1c (%)	6.7 (0.2)	5.5 (0.1)	16.5	6.2 (0.1)	5.5 (0.1)	11.3	0.02
Total cholesterol (mg/dL)	183.2 (6.0)	154.6 (3.3)	15.6	198.3 (2.9)	160.5 (1.9)	19.1	0.19
HDL-C (mg/dL)	41.7 (1.3)	44.9 (1.3)	7.7	50.4 (1.1)	49.8 (0.7)	1.1	0.04
LDL-C (mg/dL)	98.3 (4.5)	85.5 (3.0)	12.9	115.6 (2.8)	91.1 (2.2)	21.2	0.04
Triglyceride (mg/dL)	200.06 (13.7)	102.9 (4.1)	48.6	156.7 (6.7)	102.6 (2.9)	34.8	0.006

All pre- to postsurgery mean differences are statistically significant (P<0.05) except for diastolic blood pressure and HDL-C.

SE, standard error; BMI, body mass index; HbA1c, glycated hemoglobin; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol. Bold figures statistically significant.

When different BMI categories (≤40, 40 <BMI ≤50, >50) were compared by gender for all cardiometabolic outcomes, all groups showed improvement over the first year after surgery, but no BMI group differences in weight or cardiometabolic risk factors were found with the exception of weight lost. In the two higher BMI categories, men lost significantly more weight than women (Table 3).

Table 3.

Change in Cardiovascular Risk Factors from Before to 1 Year After Bariatric Surgery Among 633 Hispanics by Body Mass Index Category, 2004–2010

	Before surgery BMI ≤40		Before surgery 40<BMI ≤50		Before surgery BMI >50
	Male mean (SE) n=25	Female mean (SE) n=83	Male mean (SE) n=94	Female mean (SE) n=339	Male mean (SE) n=58	Female mean (SE) n=111	Overall group difference P value
BMI (kg/m²)	−4.7 (0.6)	−5.4 (0.3)	−6.4 (0.3)	−6.3 (0.1)	−8.5 (0.3)	−7.6 (0.3)	0.21
Weight (kg)	−14.1 (1.6)	−14.2 (0.9)	−20.4 (0.8)	−16.4 (0.4)^a	−26.2 (1.0)	−20.3 (0.7)^b	0.03
Glucose (mg/dL)	−25.7 (12.6)	−3.7 (7.5)	0.4 (7.4)	−10.1 (3.1)	−22.2 (8.2)	−13.8 (5.3)	0.1
Total cholesterol (mg/dL)	−30.9 (17.1)	−38.5 (12.1)	−26.6 (13.5)	−42.0 (4.8)	−27.3 (11.1)	−26.7 (7.8)	0.72
HDL-C (mg/dL)	5.2 (4.8)	−4.1 (3.4)	3.9 (4.0)	1.4 (1.3)	1.3 (3.1)	−1.1 (2.2)	0.57
LDL-C (mg/dL)	−12.1 (16.9)	−23.4 (12.6)	−16.9 (15.4)	−24.3 (5.2)	−8.5 (10.9)	−19.6 (8.0)	0.98
Triglyceride (mg/dL)	−119.4 (34.6)	−62.9 (24.5)	−61.2 (27.3)	−59.5 (9.9)	−88.7 (22.3)	−44.1 (16.1)	0.44

P<0.01, statistical comparison for gender difference.

P<0.0001, statistical comparison for gender difference.

BMI, body mass index; SE, standard error; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol.

Bold figures statistically significant.

Discussion

This analysis showed that Hispanic patients experienced significant improvements in numerous measures of cardiometabolic health and these improvements varied by gender. The overall sample lost 17.6 kg and showed significant improvements in SBP/DBP, fasting plasma glucose, LDL-C, TC, TGs, and HbA1c 1 year after gastric bypass surgery. Men tended to show greater improvements in weight reduction, fasting plasma glucose, and DBP versus women, but conversely, women were more likely than men to show greater improvements in SBP, LDL-C, and TC.

Our findings have important implications for morbidly obese Hispanic adults and those not of Mexican origin in particular. While Hispanics continue to rise in population in the United States, they disproportionately share the burden of obesity, type 2 diabetes, and cardiovascular disease.^2
–4 Findings from the Framingham Heart Study show that weight is the third most important predictor of heart disease after age and dyslipidemia and that each incremental rise in BMI of 1 kg/m² results in a 5% (in men) and 7% (in women) increase in the risk of heart failure. The literature is increasingly showing the long-term health benefits of bariatric surgery.⁸ Studies have showed that significant improvement in TGs, diabetes, and DBP are present as much as a decade after surgery. Similarly, others have reported a 72% decrease in the risk of cardiovascular and circulatory diseases 5 years after their patients underwent bariatric surgery.^9,10

Very little information has been available on the long-term efficacy of bariatric surgery on cardiometabolic disease risk among Hispanics of non-Mexican background. Our analysis here reveals some important implications for this group and by gender in particular. Males were significantly more likely to show postsurgery improvement in weight, HDL-C, and TGs, but women were significantly more likely than men to have postsurgery improvements in LDL-C. Our findings of a significant gender difference in improvement in HDL-C are not in agreement with some studies that report effects of gender on HDL-C, in which a more marked pattern of augmentation was present for women (the concentrations remained significantly elevated from baseline to 42 months after surgery) compared with the levels in the men.¹¹ Other studies reported similar findings in groups of patients who had undergone gastric bypass¹² or adjustable band surgery.¹³ However, there are studies that report finding no differences in the postoperative changes in HDL-C between men and women who had undergone bypass or banding.^14
–16

Several studies have suggested a role for several factors, such as gender, race age, and co-morbidities, in the outcomes after laparoscopic gastric bypass.^17

–23 In general, results show that men had significantly greater mortality, overall morbidity, intensive care unit admissions, length of stay, and suboptimal weight loss after gastric bypass surgery.²¹ The authors concluded that results of the risk-stratification analysis showed that greater illness severity and co-morbidities among men appeared to be the reason for gender differences in postoperative outcomes. Others have suggested that the reluctance among men to seek gastric bypass surgery^24,25 and the subsequently greater risk severity might have been the cause of the gender differences in the outcomes with gastric bypass surgery.

When ethnicity was compared as a predictor of weight loss, it was found that being Caucasian (versus Hispanic) predicted success in weight loss after gastric bypass. In contrast, another study showed no difference in success between Caucasians or Hispanics.²⁶ Similarly, our group has reported elsewhere significant weight loss and improvement in fasting plasma glucose and HbA1c levels as far as 3 years postsurgery among a predominantly Hispanic patient population with diagnosed and undiagnosed type 2 diabetes and prediabetes with no differences by ethnicity.²⁷

When patients were stratified by their BMI category, those who were superobese (BMI ≥50) had the most substantial weight loss 1 year postsurgery, and among men in particular. Several studies have noted that bariatric patients with a BMI ≥50 are more difficult to treat than less obese individuals, and they do not experience the percent change in postsurgery weight loss versus less obese patients, with many patients remaining in the severely or morbidly obese categories despite substantial weight loss.²⁸ Ten years after Roux-en-Y gastric bypass, Christou et al.²⁹ reported a >35 BMI 10 ten years after surgery in over half (58%) versus 20% in patients who were moderately obese presurgery. However, other studies have shown that the percentage of body weight loss is remarkably similar in moderately and severely obese patients after gastric bypass surgery.³⁰

Limitations and strengths

The main limitation to the current analysis was not having additional information available on lifestyle changes that may influence postsurgery improvements in cardiometabolic disease risk, such as increased physical activity. Strengths of this study include the large sample size and ethnic composition of the patient population, which has been largely underreported in the literature.

Conclusions

Our results here show bariatric surgery results in significant weight loss and cardiometabolic disease risk reduction among Hispanic adults and these changes vary by gender. These findings indicate that gastric bypass surgery has the potential to be a safe and effective treatment option for significant weight loss and chronic disease risk improvements among adult non–Mexican-American Hispanics. Because the incidence of metabolic syndrome is not only rising, but also more prevalent, in this demographic, bariatric surgery could be an instrumental tool in the future to combat the factors associated with cardiometabolic disease risk. This is vital, because healthcare costs associated with metabolic syndrome and its accompanying co-morbidities, such as diabetes, will continue to increase over the coming years. The Hispanic population is the fastest growing minority group in the United States; thus, bariatric surgery could prove to be an additional useful tool in the treatment of their metabolic syndrome and cardiometabolic disease.

Footnotes

Author Disclosure Statement

Dr. de la Cruz-Munoz is a consultant for Ethicon EndoSurgery. There are no conflicts of interest to report for the other authors.

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