N. Liu1, J. Birstler3, M. Venkatesh1, L. P. Hanrahan2, G. Chen3, L. M. Funk1,4,5 4University Of Wisconsin,Department Of Surgery / Division Of Minimally Invasive, Foregut, And Bariatric Surgery,Madison, WI, USA 5William S. Middleton VA Hospital,Madison, WI, USA 1University Of Wisconsin,Department Of Surgery,Madison, WI, USA 2University Of Wisconsin,Department Of Family Medicine And Community Health,Madison, WI, USA 3University Of Wisconsin,Biostatistics And Medical Informatics,Madison, WI, USA
Introduction: Obesity is a significant health problem in the US, affecting one-third of all adults. Numerous studies have reported that losing as little as 5% of total body weight (TBW) can improve comorbidities, specifically cardiovascular health. However, for adults with severe obesity, 5% TBW loss rarely results in resolution of comorbidities. The objective of this study was to quantify clinically significant weight loss during a 5-year window for severely obese patients who had not undergone bariatric surgery. We defined clinically significant weight loss as a final BMI of < 30 kg/m2. We hypothesized that less than 10% of our patients would achieve clinically significant weight loss.
Methods: All 18-75 year old patients at a single institution academic health center who had at least 2 height and weight measurements 5 years apart between 1/1/2011 and 12/31/2016 were retrospectively identified from the electronic health record (EHR). We excluded all underweight patients with BMI ≤ 18.5 kg/m2, pregnant and cancer patients using ICD-9 and -10 codes, and bariatric surgery patients using the bariatric surgery registry. We categorized patients by their initial BMI measurement: normal (18.5-24.9 kg/m2), overweight (25.0-29.9), class 1 (30.0-34.9), class 2 (35.0-39.9), and class 3 (≥ 40.0) obesity. BMI changes from initial to end date were plotted. Within each BMI group, we identified patients who lost ≥ 5% TBW.
Results: 23,769 patients met our study inclusion criteria. 19.8% were severely obese (class 2 or 3) at baseline. 25.6% of class 2 obesity patients and 29.6% of class 3 patients lost ≥ 5% TBW; 17.8% and 21.7% of overweight and class 1 patients, respectively, lost ≥ 5% TBW. The majority of patients with severe obesity (51.5% for class 2 and 81.3% for class 3) remained in the same BMI category (Figure 1). 22.4% of class 2 and 14.4% of class 3 patients lost enough weight to drop down 1 obesity class. Only 3.1% of class 2 patients and 0.5% of class 3 patients achieved clinically significant weight loss, or BMI of < 30 kg/m2.
Conclusion: Patients with severe obesity were more likely to lose at least 5% of their total weight compared to overweight and class 1 obesity patients. However, weight loss into a non-obese weight class was very uncommon over a 5-year period for patients with severe obesity. The vast majority either remained in the same obesity class or increased classes. This pattern of ongoing weight gain for the most obese patients is concerning and requires solutions at societal and health systems levels.
