A study published in the January 4 issue of JAMA reveals that bariatric surgery is linked to a reduction in cardiovascular deaths and events, such as heart attack and stroke amongst obese individuals.
According to the majority of epidemiological studies, obesity is linked to increased cardiovascular events and mortality. Background information in the article states that:
“Weight loss might protect against cardiovascular events, but
solid evidence is lacking.”
Between September 1987 and January 2001, Dr. Lars Sjostrom of the University of Gothenburg in Sweden and his team assessed the hypothesis of bariatric surgery being linked to a reduced incidence of cardiovascular events. They examined the relationship between weight change and cardiovascular events in an ongoing (Swedish Obese Subjects [SOS]) nonrandomized, prospective, controlled study and recruited 2,010 obese participants who underwent bariatric surgery from 25 public surgical departments and 480 primary health care centers in Sweden and matched them to 2,037 obese individuals (control group) who received standard care.
The study endpoint was December 31, 2009, with a midpoint follow up of 14.7 years. All eligible participants were aged between 37 to 60 years with a body mass index of at least 34 in men and at least 38 in women. In the bariatric surgery group, 13.2% underwent a gastric bypass, 18.7% of patients underwent banding, or 68.1% vertical banded gastroplasty, whilst the control group received the common administered care under the Swedish primary health care system.
The researchers performed physical and biochemical examinations and database crosschecks at preplanned intervals. In the bariatric group they observed an average change in body weight of -23% after 2 years, -17% after 10 years, -16% after 15 years and -18% after 20 years, compared with weight changes in the control group of 0% after 2 years, 1% after 10 years and -1% after 15 and 20 years.
During follow-up, the researchers noted 49 cardiovascular deaths amongst patients in the control group compared with 28 cardiovascular deaths amongst those in the surgery group. Overall, patients in the control group suffered 234 fatal and non-fatal cardiovascular events compared with 199 fatal and non-fatal cardiovascular events amongst those in the surgery group. After the researchers adjusted for a number of variables, they discovered that bariatric surgery was linked to a lower number of fatal cardiovascular deaths and a lower incidence of total cardiovascular events.
Bariatric surgery was linked to a reduced number (22) of fatal heart attack deaths compared with 37 deaths in the control group. The evaluation suggests that bariatric surgery was associated to both, reduced fatal heart attack incidence and total heart attack incidence in addition to being linked to a reduced number of fatal stroke events and total stroke events.
The findings demonstrated no important relationship between weight change and cardiovascular events in the surgery or control group. The researchers indicate that the lack of relationship between weight loss and reduction of cardiovascular events could be linked to inadequate statistical power in detecting this relationship.
The researchers state:
“Alternatively, following relatively modest weight loss induced by bariatric surgery, there is no further risk reduction attributable to greater, subsequent weight loss. Our negative findings also emphasize the need to explore weight loss independent of effects of bariatric surgery.”
“In conclusion, 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. These results – together with our previously reported associations between bariatric surgery and favorable outcomes regarding long-term changes of body weight, cardiovascular risk factors, quality of life, diabetes, cancer, and mortality – demonstrate that there are many benefits to bariatric surgery and that some of these benefits are independent of the degree of the surgically induced weight loss.”
Editorial: Inadequacy of BMI as an Indicator for Bariatric Surgery
In a linked editorial, Edward H. Livingston, M.D., of the University of Texas Southwestern Medical Center, Dallas, and Contributing Editor of JAMA, writes that:
“Although weight loss in general is desirable for obese patients, the overweight condition by itself is not informative. Physicians need to know an individual patient’s risk factor profile before initiating therapy. Weight gain can result from overeating protein that may be associated with lean body mass that is not related to adverse health. If body fat is primarily truncal, being obese may be associated with little excess health risk or little subsequent risk of reduced lifespan.
Bariatric surgery does result in weight loss, but the overall benefit of improved longevity resulting from these operations remains to be definitively proven. 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.”
He concludes stating:
“In addition, given the advances in the understanding of the pathophysiological mechanisms underlying obesity, increasing evidence on the relationship between obesity and outcomes, and progress and refinements in surgical interventions for obesity, perhaps it is time for the National Institutes of Health to convene another expert panel to rigorously assess the available evidence and provide updated recommendations for bariatric procedures for the treatment of obesity.”