HealthDay News — Bariatric surgery reduces the long term risk for heart attack and stroke and decreased cardiovascular death in obese individuals, data published in the Journal of the American Medical Association indicate.
During a median 14.5 year follow-up period, any bariatric procedure reduced the risk for a first fatal or nonfatal cardiovascular event by 33% compared with no bariatric surgery in obese individuals (P<0.001), even after adjusting for potential confounding factors, Lars Sjöström, MD, PhD, from Sahlgrenska University Hospital in Gothenburg in Sweden, and colleagues found.
Data also indicated that cardiovascular deaths were reduced by a relative 53% after surgery compared with no surgery (P=0.002).
“This is the first prospective, controlled intervention to our knowledge reporting that bariatric surgery is associated with reduced incidence of cardiovascular deaths and cardiovascular events,” the researchers wrote.
However, reduced cardiovascular events among the surgical patients were not related to either baseline weight or weight loss, the researchers noted.
They investigated the association between bariatric surgery, weight loss and cardiovascular events in obese individuals that participated in the Swedish Obese Subjects study. Participants were aged 37 to 60 years, with a BMI of at least 34 kg/m² in men and 38 kg/m² in women, and were recruited from 1987 to 2001.
Participants included 2,010 obese individuals who underwent bariatric surgery (gastric bypass, banding or vertical banded gastroplasty) and 2,037 matched obese controls who opted to receive usual care. The primary end point, published in 2007, was total mortality; myocardial infarction and stroke were secondary end points.
The investigators found that bariatric surgery was associated with a significant reduction in the number of cardiovascular deaths (28 vs. 49 deaths in the surgery and usual care groups, respectively; adjusted HR=0.47). The number of total first-time cardiovascular events, defined as myocardial infarction or stroke, was significantly lower in the surgery group compared with the usual care group (199 vs. 234 events; adjusted HR=0.67).
Edward H. Livingston, MD, of the University of Texas Southwestern Medical Center in Dallas, questioned the absolute benefits of bariatric surgery in an accompanying editorial, pointing out that although the study period was long, the observed reductions in CVD events and mortality involved relatively few events.
Findings from a previous study indicated a 30% reduction in all-cause mortality with bariatric surgery translated to only a 1.3% mortality difference between groups (5.0% versus 6.3% at a mean follow-up of 10.9 years), Livingston pointed out.
Furthermore, the researchers acknowledged study limitations including a lack of randomization due to high surgical mortality rates among patients that underwent bariatric procedures in the 1980s and a study population consisting only of white patients.
Several criterion for bariatric surgery eligibility, inculding post hoc analyses and baseline BMI, as well as waist-to-hip ratio and waist circumference did not predict the observed cardiovascular benefit with bariatric surgery.
“Because the expected health benefits do not necessarily exceed the risks of weight loss operations, obese patients without other weight-related complications generally should not undergo bariatric surgery,” Livingston concluded, adding that diabetes and other obesity complications may be more important predictors of lifespan than obesity along.
Several study researchers disclosed financial ties to the pharmaceutical, biotechnology and weight-loss industries. Study funding was obtained from Hoffmann LaRoche, AstraZeneca, Cederroths, Sanofi-Aventis and Johnson & Johnson.
Sjöström L et al. JAMA 2012; 307: 56-65.
Livingston EH. JAMA. 2012; 307: 88-89.