Division of Gastrointestinal and Minimally Invasive Surgery, Carolinas Medical Center, Charlotte, North Carolina, USA.
Surg Obes Relat Dis. 2011 Jul-Aug;7(4):531-4. doi: 10.1016/j.soard.2010.09.025. Epub 2010 Oct 11.
The percentage of excess weight loss (%EWL) is a common metric for reporting weight loss after bariatric surgery. The %EWL can vary depending on the definitions of ideal body weight (IBW) used and the preoperative weight. The present study examined the effect of variations in IBW and the preoperative weight on the %EWL at a tertiary care teaching hospital.
After institutional review board approval, we reviewed the prospectively collected data from consecutive patients who had undergone laparoscopic adjustable gastric banding or laparoscopic Roux-en-Y gastric bypass (RYGB) at our center from 2005 to 2008 with a single surgeon (T.K.). All patients with ≥12 months of follow-up were included. The IBW was calculated using the mean weight of the "medium frame" and the maximum weight of the "large frame" for the corresponding height from the Metropolitan Life Insurance tables. The preoperative weight was defined as the weight on the day of surgery or the greatest recorded preoperative weight between the initial consult and the day of surgery. The postoperative weight was defined as the 12-month follow-up weight. Four methods were used to calculate the %EWL. Repeated measures analysis of variance was used to analyze the methods.
A total of 173 patients met inclusion criteria. Of these 173 patients, 126 underwent RYGB and 47 underwent laparoscopic adjustable gastric banding. The calculated 12-month %EWL for these was 65-82% for RYGB and 31-46% for laparoscopic adjustable gastric banding using the calculation method.
For a given postoperative weight loss, significant variance will be found in the %EWL (≤17%), depending on the definition of IBW used and the preoperative weight value used. This highlights the need for a standardized approach for reporting weight loss in bariatric studies. Investigators should define their methods clearly, and readers should keep this variability in mind when interpreting the %EWL.
减重百分比（%EWL）是报告减重手术后体重减轻的常用指标。%EWL 可能因所使用的理想体重（IBW）定义和术前体重而异。本研究在一家三级教学医院检查了 IBW 和术前体重变化对%EWL 的影响。
在获得机构审查委员会批准后，我们回顾了 2005 年至 2008 年间由同一位外科医生（T.K.）在我们中心接受腹腔镜可调节胃带或腹腔镜 Roux-en-Y 胃旁路术（RYGB）的连续患者的前瞻性收集数据。所有随访时间≥12 个月的患者均被纳入。IBW 是根据“中框”的平均体重和相应高度的“大框”的最大体重从大都会人寿保险表计算得出的。术前体重定义为手术当天的体重或手术当天之前初始咨询和手术之间记录的最大术前体重。术后体重定义为 12 个月的随访体重。使用了四种方法来计算%EWL。使用重复测量方差分析来分析这些方法。
共有 173 名患者符合纳入标准。在这 173 名患者中，126 名患者接受了 RYGB，47 名患者接受了腹腔镜可调节胃带术。使用计算方法，这些患者的 12 个月%EWL 为 RYGB 为 65-82%，腹腔镜可调节胃带术为 31-46%。
对于给定的术后体重减轻，根据所使用的 IBW 定义和术前体重值，%EWL（≤17%）将存在显著差异。这突出表明在减重研究中报告体重减轻需要标准化方法。研究人员应明确界定其方法，读者在解释%EWL 时应牢记这种变异性。
