On December 31, 2009, in Uncategorized, by Andrea

I’m all about the emotions today.

This is a study regarding adolescents undergoing RNY — specifically, it states that those with a lower BMI before surgery will have a lower BMI 1 year after surgery.  Those with a higher BMI prior to surgery (and they were looking at kids — and here’s where the sadness hits — with a BMI between 65 and 95) remain “extremely obese” one year post-op.

This is a limited study — only looking at a limited number of kids (61) and only follow them for one year.  We know that those that are super morbidly obese can continue to lose long past the year mark, so it is not as if the kids in the two groups with the larger BMIs (group 1 had BMIs between 40 and 54.9, group 2 had BMIs between 55 and 64.9, and group 3 had BMIs between 65 and 95) should be written off as “failures” by the medical community.  To do so would be extremely short-sighted and just plain incorrect.

For purposes of reading the study, nadir is defined as “the lowest point.”

From Medscape:

In Adolescents, Baseline BMI Predicts Nadir BMI After Gastric Bypass

NEW YORK (Reuters Health) Dec 29 – In adolescents undergoing gastric bypass surgery, baseline body mass index (BMI) predicts nadir BMI, a new study shows.

But regardless of baseline BMI, gastric bypass improves cardiovascular risk factors and brings BMI down by about 37% in all patients, the authors report in the January Journal of Pediatrics.

“This finding suggests that the timing of surgery for adolescent obesity is an important consideration, as ‘late’ referral for bariatric surgery at higher BMI values may preclude reversal of obesity or extreme obesity within the first post-operative year and may increase the risk of weight regain over the long term,” according to lead author Dr. Thomas H. Inge, of Cincinnati Children’s Hospital Medical Center, Ohio, and colleagues.

“The BMI spectrum for adolescents seeking surgery is broad, with values in the literature ranging from 35 to 95 kg/m squared, with average BMI values much higher than those seen in most adult surgical practices,” Dr. Inge and his co-authors point out.

To determine the effect of preoperative BMI status on outcomes in their younger patients, the investigators followed 61 adolescents for a year after laparoscopic Roux-en-Y gastric bypass. Nearly 70% were female, more than 80% were white, and their average age at surgery was 17.2 years.

In all cases, patients were left with a gastric pouch volume of 30 ml, and the jejunum was divided 15 to 20 cm from the ligament of Treitz.

Patients were stratified into three groups based on preoperative BMI (kg/m squared): Group 1, n = 23: BMI 40.0 to 54.9; Group 2, n = 21: BMI 55.0 to 64.9; and Group 3, n = 17: BMI 65.0 to 95.0.

The mean BMI in the overall cohort, which was 60.2 kg/m squared at baseline, fell by 37.4% at 1 year after surgery (p < 0.0001), with little variation in BMI reduction among the groups (37.2% in Group 1, 36.8% in Group 2, and 37.7% in Group 3).

The rate of change in absolute BMI units did vary significantly by group, however, with one-year nadir BMI (kg/m squared) reaching 31 in Group 1, 38 in Group 2, and 47 in Group 3.

Only 10 patients (17%) achieved a BMI of less than 30 kg/m squared at 1 year. Eight of these were from Group 1.

Systolic and diastolic blood pressures fell significantly after surgery by 8.8% and 13.5%, respectively, regardless of baseline BMI (P < 0.0001 for each). Surgery also reduced total cholesterol (by 16.8%; p = 0.0007), triglycerides (by 37.3%; p < 0.0001), and insulin (by 75.8%; p < 0.0001), no matter the baseline BMI.

Albumin levels did not change at 1 year despite the significant weight loss.

“In this investigation, we found that most adolescents within the highest ranges of baseline BMI…remained extremely obese…despite BMI reductions averaging nearly 40%,” the authors write.

Adolescents “who present at higher weights and BMI values lose more weight than those who present at lower weights but also plateau at a higher weight on average,” they add. “The biological and potentially behavioral reasons for this are unclear.”

J Pediatr 2010;156:103-108.

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