Surgery for Obesity Pays Off

Summarized by Robert W. Griffith, MD
September 28, 2007

Summary

Two large studies show that bariatric surgery in obese people leads to prolonged weight loss and reduced overall mortality, compared with conventional treatment of obesity.

Introduction

The prevalence of obesity in the USA doubled between 1980 and 2004, so that now 30% of the population is classified as obese, i.e. their body mass index (BMI) is 30 or higher. Obesity is linked to increased mortality, with the life of severely obese people reduced by 5 to 20 years. While weight loss has been shown to decrease the cardiovascular risk factors seen in obesity, it has not lowered mortality in well-conducted studies done to date.

Retrospective studies have suggested that obese subjects treated with bariatric surgery can result in reduced mortality; however, there are no well-controlled prospective studies, until now. The results of the Swedish Obese Subjects study, which followed over 4,000 obese people with and without surgery for 10 years, have just been published in the New England Journal of Medicine.

What was done

A total of 4047 obese subjects were enrolled at 25 surgical and 480 primary-care centers in Sweden. Of these, 2010 had bariatric surgery and 2037 received conventional treatment, acting as controls. Enrollment lasted 13 years, from1987 to 2001; at the time of analysis in 2005, the follow-up period ranged from 4 to 18 years, with an average of 10.9 years.

All subjects had to be between 37 and 60 at enrollment, with a BMI of 34 or more (men) or 38 or more (women). There were no exclusions for previous cardiovascular disease, high blood pressure, diabetes, or lipid disturbances. The alive-or-dead status of 99.9% of the subjects was available for analysis; only 3 subjects were lost to follow-up. Cause of death was established for all deaths.

Of the 2010 subjects in the surgery group, 376 had gastric banding, 1369 had banded gastroplasty, and 265 underwent gastric bypass (see first link below for information on these). The 'conventional treatment' for the controls ranged from sophisticated lifestyle intervention and behavior modification to no treatment whatsoever.

What was found

At baseline, the average age of the subjects was 48 years; 70% of them were women. More of those in the surgery group smoked than in the control group (25% vs. 20%), and they were slightly heavier (BMI 42 vs. 40) with high blood pressures (145 vs. 138 mm Hg systolic, 90 vs. 85 mm Hg diastolic).

Weight change in the controls was minimal throughout the 10-year follow-up period. The greatest weight loss in the surgical group was seen after 1 to 2 years; with gastric bypass, it reached 32%, with gastroplasty 25%, and with banding 20%. After 10 years, the weight losses compared with baseline were 25% for bypass, 16% for gastroplasty, and 14% for banding. In the (fewer) subjects examined after 15 years, weight losses were 27%, 18%, and 13%, respectively.

There were 129 (6.3%) deaths in the control group and 101 (5.0%) in the surgery group. )Two control and 5 surgery subjects died within 90 days of baseline.) After adjusting for differences in sex, age, and numerous risk factors, the overall mortality rate was 29% lower in the surgery group. The most common causes of death were heart attack (25 controls, 13 surgery subjects) and cancer (47 controls, 29 surgery subjects).

After surgery, re-operations or 'conversion' surgeries were necessary in 31% of the banding subjects, 21% of the gastroplasties, and 17% of the bypasses.

What the findings mean

The results speak for themselves. Bariatric surgery in obese people led to prolonged weight loss and reduced overall mortality, compared with conventional treatment of obesity. Probably the only major criticism that can be directed at this study was the absence of randomization to one treatment group or the other; it's probable that this would be an impossible requirement for a study of bariatric surgery mortality.

There's another report of gastric bypass mortality in the same issue of the Journal.¹ In a retrospective study, over 7500 obese patients who had received this surgery were matched with an equal number of obese people applying for a driving license, using age, sex, and BMI for matching. The rates of death from any cause were compared over an average of 7 years. There were 38 deaths per 10,000 person-years in the surgery group, compared with 57 in the controls. In particular, deaths due to diabetes, heart disease, and cancer were reduced in the surgery group.

These two major publications indicate clearly that bariatric surgery is a valuable treatment option for the severely obese. Further studies will clarify the pros and cons for the various types of surgery. But perhaps there's less reason now for the hesitant patient to delay their decision.

Source

• Optical markers in duodenal mucosa predict the presence of pancreatic cancer. Y. Liu, RE. Brand, V. Turzhitsky,  et al., Clin Cancer Res, 2007, vol. 13, pp. 4392--4399

Footnotes
1. Long-term mortality after gastric bypass surgery. TD. Adams, RE. Gress, SC. Smith,  et al. , N Engl J Med, 2007, vol. 357, pp. 753--761

Related Links
Bariatric Surgery Options
Obesity Surgery and High Blood Pressure
Surgery for Obesity Helps Treat Diabetes
Keyhole Surgery or Intense Dieting for Obesity?

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