A Comparison of Diet and Exercise Therapy Versus Laparoscopic Roux-En-Y Gastric Bypass Surgery for Morbid Obesity: A Decision Analysis Model
Bibliographic record
Abstract
BACKGROUND: In the absence of randomized controlled trials that directly compare medical versus surgical treatment of morbid obesity, decision analysis is a useful tool to help determine the optimal treatment strategy. Using decision analysis we simulated a trial comparing diet and exercise therapy to laparoscopic gastric bypass surgery to determine which approach resulted in longer life expectancy. STUDY DESIGN: A Markov decision analysis model was constructed to evaluate survival after laparoscopic Roux-en-Y gastric bypass surgery compared with a diet and exercise program for a 45-year-old woman with a body mass index (BMI) of 40 kg/m(2). Baseline mortality data were derived from published tables of vital statistics, and the relative risks of death associated with obesity (relative to normal weight) were taken from epidemiologic studies. We assumed that successful surgery resulted in a reduction of BMI to 30 kg/m(2). The baseline assumptions were: an operative mortality of 0.4%; a probability of weight loss after surgery of 80%; a rate of weight loss on a diet and exercise program, 20% at two years; a rate of regain of lost weight, 95% at two years; a relative risk of death for a BMI of 40 kg/m(2), 2.70; and a relative risk of death for a BMI of 30 kg/m(2), 1.51. RESULTS: The undiscounted life expectancy after surgery was 69.7 years compared with 67.3 years for a diet and exercise program (an absolute increase in life expectancy of 2.4 years, a relative increase in life expectancy of 10.8%). Sensitivity analyses assumed discounting at 5%/y, and showed that surgery was associated with a longer expectation of life when the risk of operative mortality was less than 10%, and when the probability of weight loss after surgery was greater than 4%. CONCLUSIONS: In a decision analysis model, laparoscopic gastric bypass surgery for morbid obesity was associated with a substantially longer survival than diet and exercise therapy.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.012 | 0.020 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.004 | 0.004 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.004 | 0.003 |
| Insufficient payload (model declined to judge) | 0.009 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".