Researchers from Brazil have developed and validated an accurate predictive model that comprises the sum of five outcome variables to predict success of Roux-en-Y gastric bypass (RYGB) based exclusively on patients’ preoperative characteristics. The findings could be used to prioritise patients with the best indication for the procedure and incorporated in the public health system as a support tool in the decision-making process.
The study authors reported that preoperative predictors of success included lower age, presence of non-alcoholic fatty liver disease (NAFLD) and obstructive sleep apnoea (OSA), more years of continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) use, negative history of cardiovascular disease and lower number of antihypertensive drugs.
They authors stated that there are currently no criteria to establish priority for bariatric surgery candidates in the Brazilian public health system and the waiting time regime adopts a first-in-first-out queue rule. In addition, although a few scoring systems have been developed, most assess early postoperative mortality predictors or long-term mortality predictors including individuals with overweight and obesity that have not undergone bariatric surgery. However, as bariatric surgery is an elective procedure identifying patients who would obtain the greatest benefits is essential to organise the access to surgery.
Therefore they designed a study, ‘Development and Validation of a Predictive Model of Success in Bariatric Surgery’, reported in Obesity Surgery, that sought to identify preoperative characteristics (four assessed at baseline and one year after the surgery, and one outcome assessed only after the surgery (all-cause mortality)) that predict the post-operative ‘success’ after bariatric surgery and prioritise patients with the best indication for the procedure. The success of the surgery was defined as the sum of the following five outcome variables: excess weight loss, the use of CPAP or BiPAP as a treatment for OSA, daily use of antidiabetics (including insulin), daily use of antihypertensive medication and all-cause mortality.
The study included 461 patients (female, 84.6%), white (89.4%), with a mean age of 42.3±10.8 years and the preoperative BMI 35.0-89.2 with a median excess weight of 61.4 (48.5–77.5) kg. Self-reported mean duration of obesity was 18.7 ± 9.6 years. Median waiting time for surgery was 30 months.
At one-year, excess weight loss was 68.6 ± 17.3%, 17 patients died and of those eight deaths were related to obesity or surgery complications (sepsis, bronchospasm, hypovolemic shock and respiratory failure). The authors noted that mortality records sometimes went beyond the one-year follow-up.
Table 1 shows the sample of patients divided in three similar sized groups after being organised in ascending order, according to a composite indicator that added the patient’s success index value and four variables indicating the presence of four comorbidities, with binary outcomes (1=presence; 0=absence).
“The success index may help in prioritising eligible patients waiting for bariatric surgery with the highest indication for the procedure and should be considered for incorporation in the public health system as a support tool in the decision-making process,” they concluded.
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