May 15, 2012 (Lyon, France) — Bariatric surgery is associated with an increased likelihood that patients will report and be diagnosed with problems related to alcohol consumption. Different levels of risk are associated with different gastric surgery procedures, Per-Arne Svensson, PhD, from the Sahlgrenska Center for Cardiovascular and Metabolic Research at the University of Gothenburg in Sweden, reported here at the 19th European Congress on Obesity.
The nonrandomized prospective Swedish Obese Subjects (SOS) trial matched 2010 patients undergoing bariatric surgery in 25 surgical departments from 1987 to 2001 with 2037 contemporary control subjects. People who had alcohol problems at baseline or who consumed more than 34 g/day of pure alcohol (equivalent to 3 bottles of wine per week) were excluded from the study.
The treating surgeon determined the kind of surgery; 19% of patients underwent gastric banding, 68% underwent vertical banded gastroplasty, and 13% underwent gastric bypass surgery. At baseline, the mean ages in the 3 surgery groups and in the control group were 47.0 to 48.7 years (range, 37 to 60 years), and mean body mass indices were 40.1 to 43.9 kg/m². There were no differences in alcohol-related parameters in the groups.
Previous results from the SOS study showed that gastric bypass produced the greatest long-term weight loss, and that gastric banding and vertical banded gastroplasty produced similar degrees of weight loss. It has also shown that alcohol consumption decreases in the first 6 months after gastric bypass, but subsequently increases.
Dr. Svensson and colleagues assessed the long-term changes in alcohol consumption and abuse after bariatric surgery. Median follow-up time was 10 years. Alcohol consumption was self-reported for the previous 3 months, and alcohol problems were self-reported at progressively longer time intervals after surgery. Data on diagnosed alcohol abuse came from a national register, according to International Classification of Diseases codes (ICD-9 and ICD-10).
The World Health Organization defines medium-risk alcohol consumption as 40 g/day for men and 20 g/day for women. Men and women in the control and bariatric surgery groups, as a whole, were well below these respective levels.
"During the first year, we actually see a reduction in alcohol consumption," which is similar to what has previously been reported, Dr. Svensson said. "But things change over time."
For men, median alcohol consumption in the gastric bypass group increased. However, because of individual variation in the groups, the researchers looked at the cumulative incidence of the alcohol-related parameters.
Medium-risk alcohol consumption was greatest with gastric bypass (about 14% at 10 years and 20 years for men and women combined, compared with about 5% in the control group). Self-reported alcohol problems and alcohol abuse diagnoses were also greatest with gastric bypass. For vertical banded gastroplasty, the incidence of medium-risk alcohol consumption fell between the gastric bypass and control groups. For gastric banding, the incidence did not differ significantly from that in the control group.
Adjusted Hazard Ratios, Compared With Control Group (95% Confidence Interval)*
| Type of Surgery | Medium-Risk Alcohol Consumption | Self-Reported Alcohol Problems | Diagnosed Alcohol Abuse |
| Gastric bypass | 5.91 (3.40–10.39) | 2.69 (1.58–4.57) | 4.97 (2.70–9.15) |
| Vertical banded gastroplasty | 1.52 (1.09–2.11) | 2.30 (1.45–3.66) | 2.23 (1.38–3.59) |
| Gastric banding | 1.22 | 1.44 | 1.57 |
Possible mechanisms contributing to the alcohol abuse are the faster transport of alcohol to the small intestine and the reduced first-pass metabolism of ethanol by alcohol dehydrogenase in the stomach, leading to higher peak blood alcohol levels after gastric bypass surgery, and alterations in gastrointestinal hormones. Dr. Svensson speculated that there might also be "addiction transfer," in which alcohol addiction substitutes for food addiction.
He concluded that gastric bypass and vertical banded gastroplasty increased the risk for alcohol-related problems, with gastric bypass presenting the most risk. He suggested that healthcare professionals and patients be informed of these risks.
Luca Busetto, MD, from the Department of Medical and Surgical Sciences at the University of Padova in Italy, who was not involved in the trial, told Medscape Medical News that the potential for alcohol abuse after bariatric surgery has been known for many years, but that now we probably "have a more precise estimation of the numbers of the problem."
Dr. Busetto explained that in gastric bypass surgery, the pylorus is bypassed, "so the alcohol goes directly into the jejunum and is absorbed very rapidly. You may have a higher peak in alcoholemia after the same amount of wine," which can be a problem if someone is prone to alcohol addiction and experiences the effect of the consumed alcohol more rapidly. He said that studies have shown this faster absorption rate.
He noted that alcohol problems occur in a relatively small minority of patients. "It's a minor problem in comparison to the benefits [of surgery], but it's a problem that a doctor caring for patients with gastric bypass should be aware of," Dr. Busetto said.
In his experience, "in the first year after bariatric surgery, everything goes perfectly." Patients lose weight, are happy, attend all appointments, and follow the prescriptions — they are perfect patients. "After that, things change," he said. "So in bariatric surgery...you need to wait at least 5 years to have reliable results."
Commercial entities funding the study were Hoffmann La Roche, Cederroth, AstraZeneca, sanofi-aventis, and Ethicon Endosurgery. Dr. Svensson and Dr. Busetto have disclosed no relevant financial relationships.
19th European Congress on Obesity (ECO): Abstract 155. Presented May 11, 2012.
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