Gastric Bypass, Obesity, Morbid
Conditions
Keywords
Obesity, Morbid, Bariatric Surgery, Gastric Bypass, Calcium Metabolism Disorders, Vitamin D, Bone Density, Body Composition, Weight Loss
Brief summary
Obesity is a chronic illness of staggering proportions. Because weight loss through diet and exercise is difficult to attain and maintain, there has been escalating interest in bariatric surgery, including Roux-en-Y gastric bypass. Gastric bypass surgery results in long-term weight loss, dramatic improvement in comorbidities such as diabetes, and decreased mortality. Emerging evidence suggests, however, that gastric bypass may have negative effects on bone health. Because of the serious consequences of osteoporosis and fracture, this is of great concern. This study of the effects of gastric bypass on calcium metabolism and the skeleton may positively impact the clinical care of gastric bypass patients by their surgeons, primary care providers, and endocrinologists. Further, the knowledge gained may inform future investigation into the relationships between obesity, weight loss, and bone biology.
Interventions
None listed
Sponsors
VA Office of Research and Development
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
25 Years to 70 Years
Healthy volunteers
No
Inclusion criteria
Scheduled to undergo gastric bypass surgery. Please note that to be eligible, one must already be working with a bariatric surgeon and with plans in place to undergo gastric bypass. This study is unable to arrange or pay for gastric bypass surgery.
Exclusion criteria
* Perimenopausal women * Known intestinal malabsorption * Prior bariatric surgery * Use of medications known to impact bone and mineral metabolism * Disease known to affect bone * Illicit drug use or alcohol use \>3 drinks/day * Serum calcium \>10.2 mg/dL * Calculated creatinine clearance \<30 mL/min * Weight \>350 pounds * Wrist circumference \>12 inches or calf circumference \>17 inches
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Intestinal Calcium Absorption | 6 months (between baseline and 6 months) | Change in fractional calcium absorption, determined by dual stable isotope method. Fractional calcium absorption is the fraction of ingested calcium that is absorbed, which is expressed here as the percentage of ingested calcium that is absorbed. The 6-month change is the mean difference in percentage absorption between time points. For example, if fractional calcium absorption were to decrease from 30% preoperatively to 25% at the 6-month postoperative time point, the change in fractional calcium absorption would be -5%. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Areal Bone Mineral Density (BMD) at the Femoral Neck | 12 months post-operatively (between baseline and 12 months) | Areal BMD at the femoral neck by dual-energy X-ray absorptiometry (DXA). The 12-month change is the percentage change between the 12 month and baseline time points. |
| Trabecular Number at the Tibia | 12 months post-operatively (between baseline and 12 months) | Trabecular number at the tibia by high-resolution peripheral quantitative computed tomography (HR-pQCT). The 12-month change is the percentage change between the 12 month and baseline time points. HR-pQCT images were analyzed using the manufacturer's standard clinical evaluation protocol, with trabecular structure extracted using a threshold-based binarization process. |
Countries
United States
Participant flow
Recruitment details
Women and men 25-70 years of age were recruited from two academic bariatric surgery centers (the University of California, San Francisco and the San Francisco Veterans Affairs Medical Center), where surgeons used the same standardized surgical approach to Roux-en-Y gastric bypass.
Participants by arm
| Arm | Count |
|---|---|
| Gastric Bypass Surgery Patients Obese men and women undergoing gastric bypass surgery | 55 |
| Total | 55 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | No longer eligible (sleeve gastrectomy) | 3 |
| Overall Study | Withdrawal by Subject | 4 |
Baseline characteristics
| Characteristic | Gastric Bypass Surgery Patients |
|---|---|
| Age, Continuous | 45.8 years STANDARD_DEVIATION 11.2 |
| Body mass index | 44.2 kg/m2 STANDARD_DEVIATION 7 |
| Diabetes status Diabetic | 22 participants |
| Diabetes status Not diabetic | 33 participants |
| Ethnicity (NIH/OMB) Hispanic or Latino | 6 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 49 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Femoral neck areal bone mineral density (DXA) | 0.949 g/cm2 STANDARD_DEVIATION 0.133 |
| Menopausal status N/A (Men) | 11 participants |
| Menopausal status Postmenopausal | 14 participants |
| Menopausal status Premenopausal | 30 participants |
| Percentage body fat | 46.7 percentage of body fat STANDARD_DEVIATION 5.9 |
| Race (NIH/OMB) American Indian or Alaska Native | 1 Participants |
| Race (NIH/OMB) Asian | 3 Participants |
| Race (NIH/OMB) Black or African American | 12 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 2 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 37 Participants |
| Region of Enrollment United States | 55 participants |
| Sex: Female, Male Female | 44 Participants |
| Sex: Female, Male Male | 11 Participants |
| Spine volumetric bone mineral density (QCT) | 0.159 g/cm3 STANDARD_DEVIATION 0.036 |
| Weight | 122.7 kg STANDARD_DEVIATION 19.3 |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | — / — |
| other Total, other adverse events | 3 / 55 |
| serious Total, serious adverse events | 1 / 55 |
Outcome results
Primary
Change in Intestinal Calcium Absorption
Change in fractional calcium absorption, determined by dual stable isotope method. Fractional calcium absorption is the fraction of ingested calcium that is absorbed, which is expressed here as the percentage of ingested calcium that is absorbed. The 6-month change is the mean difference in percentage absorption between time points. For example, if fractional calcium absorption were to decrease from 30% preoperatively to 25% at the 6-month postoperative time point, the change in fractional calcium absorption would be -5%.
Time frame: 6 months (between baseline and 6 months)
Population: Participants from the cohort who underwent assessment of fractional calcium absorption preoperatively and 6 months postoperatively
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Gastric Bypass Surgery Patients | Change in Intestinal Calcium Absorption | -25.8 % of ingested calcium that is absorbed | Standard Deviation 15.3 |
Secondary
Areal Bone Mineral Density (BMD) at the Femoral Neck
Areal BMD at the femoral neck by dual-energy X-ray absorptiometry (DXA). The 12-month change is the percentage change between the 12 month and baseline time points.
Time frame: 12 months post-operatively (between baseline and 12 months)
Population: participants who underwent DXA at pre-op and 12-month post-op time points
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Gastric Bypass Surgery Patients | Areal Bone Mineral Density (BMD) at the Femoral Neck | -8.0 percent of baseline value | Standard Deviation 4.9 |
Secondary
Trabecular Number at the Tibia
Trabecular number at the tibia by high-resolution peripheral quantitative computed tomography (HR-pQCT). The 12-month change is the percentage change between the 12 month and baseline time points. HR-pQCT images were analyzed using the manufacturer's standard clinical evaluation protocol, with trabecular structure extracted using a threshold-based binarization process.
Time frame: 12 months post-operatively (between baseline and 12 months)
Population: participants who underwent HR-pQCT at pre-op and 12-month post-op time points
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Gastric Bypass Surgery Patients | Trabecular Number at the Tibia | -4.6 percent of baseline value | Standard Deviation 8.4 |