Benefits of some weight-loss surgeries diminish over time

File photo of medical instrument being passed to surgeon.

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Weight-loss surgeries for obesity have gained popularity in recent years, often producing dramatic weight loss and a decrease in obesity-related health problems in the short term.

But the results may not last over the long haul. A new study, published Wednesday in JAMA Surgery, analyzed patient records at one hospital between one and five years after laparoscopic sleeve gastrectomy (LSG), an increasingly common form of bariatric surgery. It found many patients who had that type of surgery experienced significant weight regain and a return of type 2 diabetes several years later.

"The longer follow-up data revealed weight regain and a decrease in remission rates for type 2 diabetes mellitus and other obesity-related co-morbidities," lead author Dr. Andrei Keidar of Beilinson Hospital in Petah Tikva Israel, said in a statement.

"These data should be taken into consideration in the decision-making process for the most appropriate operation for a given obese patient."

Few studies exist on long-term results for this specific, newer type of weight-loss surgery -- or comparisons to long-term results of other surgical options, like the often-used gastric bypass surgery.

This study collected and reviewed the checkup information for 443 patients at Rabin Medical Center at Beilinson Hospital in Peta Tikvah, Israel, who had LSG between 2006 and 2013. LSG surgery involves removing a large portion of the stomach, leaving behind a narrow "sleeve" to limit its size and reduce the natural stomach's hunger signals.

The patients maintained weight loss soon after the surgery, but gradually regained more of the weight. The weight loss success of bariatric surgeries is defined as losing at least half of the amount of weight that is above normal. The study showed that these LSG patients had excess weight loss of 77 percent after the first year, 70 percent after three years, and a much lower 56 percent at the five-year exam.

The battle against type 2 diabetes proved even more challenging over time for these LSG patients. Remission rates for the patients who completed follow-up exams were 51 percent after the first year, 38 percent after 3 years, and only 20 percent after five years.

High blood pressure, or hypertension, was reduced to normal levels for a little less than half the patients at each checkup.

The study is relatively small and includes information from only one hospital. The study was also limited by the fluctuation in patient follow-up. Patients in the hospital were scheduled for follow-up exams at 1, 3, 6 and 12 months and every year after, but many did not follow the schedule, especially as time went on. This limited the amount of data and could have added bias since patients with some conditions may be more likely to pursue follow-up care than others.

But these results do lead to more questions about comparing the long-term results of different forms of weight-loss surgery.

"The study is retrospective and it's certainly interesting because it sheds some light on long-term results for sleeve at five years," Dr. Namir Katkhouda, professor of surgery at the Keck School of Medicine of the University of Southern California and director of the bariatric surgery program, told CBS News.

"There are numerous studies that seems to hint that the sleeve is maybe less effective than the gastric bypass on long-term efficacy in the treatment of diabetes," said Katkhouda, who has worked with lead author Keidar previously. This results of this study, he added, "begs the ultimate question of comparing prospectively, in a randomized fashion, the sleeve to the bypass. And then we'll see who emerges as the winner."

Long-term benefits are an important measurement because the average age of people having bariatric surgeries is 40 to 50 years old, so they are expected to live for quite some time. Morbid obesity, defined as a body mass index of 40 or more, puts people at the highest risk for heart disease, stroke, type 2 diabetes and certain types of cancer, according to the CDC.

Bariatric surgery options still have the most positive outcomes for the treatment of morbid obesity, according to several recent studies. The condition has proven extremely hard to combat through non-surgical methods.

"Weight loss surgery, if you are morbidly obese and you have tried and failed other conservative methods," said Katkhouda, "[is] a very safe and effective operation for weight loss and for treatment of other co-morbidities, such as hypertension and especially type 2 diabetes. That remark includes the laparoscopic Roux-en-Y gastric bypass, and the sleeve. I find both very effective and safe."