FDA AdCom Strongly Supports Abandoning Excess Weight Loss
Monday, May 14, 2012
Relative Size Illusion
Regular readers may recall previous posts on the widespread reporting of weight loss in surgical studies as ‘excess weight loss’ – a meaningless number based on outdated concepts of ‘ideal weight’. In fact, not only is there is little correlation between the amount of weight lost and improvements in post-surgical morbidity and mortality but there is nothing to suggest that using this measure does anything more than amplify the numbers – after all a rather remarkable 60% EWL is little more than 20% of initial weight – but of course 60% sounds so much better.
I was therefore happy to see that last week, at the FDA hearing on obesity devices, according to Close Concerns:
“There was nearly unanimous support for using percentage of total body weight rather than percentage of excess weight loss as a study endpoint. Panelists cited the “significant flaws” in excess weight loss, especially the challenge of applying it to individuals with lower BMIs. In contrast, many believed that using percentage of total body weight loss provided a more valid metric for people at both high and low BMIs.”
Hopefully, surgeons and surgical device makers will take note and comply with what I am hoping the FDA will from now on like to see in all future submissions – strict reporting of percentage of ‘total weight loss’ rather than the confusing, arbitrary, and scientifically unsound use of ‘excess weight loss’, which I fear the surgeons may find hard to abandon.
AMS
Brooks, Alberta
Wednesday, May 16, 2012
Dr. Sharma, your thoughts about the less-used (but perhaps more relevant) excess BMI loss % (%EBMIL) – i.e. what percentage of BMI over 25% is lost? I would agree that the old IBW tables are terribly flawed, and total body weight loss does help clinically evaluate how an individual patient is doing, but how does one use total body weight loss to compare therapies when the outcome seems magnified for a group of patients with a lower average body weight? (i.e. a selected group of patients with BMI 30-35 – and perhaps an EOSS of 1 – seems to lose “more” body weight with drug X than a group of patients with BMI of 40-50 does with adjustable gastric band…the headlines read “Drug X more powerful than surgery!”)
…Maybe %EOSS reduction should be the new metric!