Does Preoperative Weight Loss Predict Significant Postoperative Weight Loss Among Patients who Underwent Laparoscopic Sleeve Gastrectomy?

Abstract

Background Some bariatric practices, mainly those conducted under public-funded services, have adopted achieving a target preoperative weight loss (PrWL) before offering surgery. There are varied opinions on the correlation between preoperative and postoperative weight loss (PoWL) for the different surgical options. This study investigated the impact of target PrWL on PoWL for patients who underwent laparoscopic sleeve gastrectomy (LSG). Materials and methods A longitudinal retrospective cohort study was carried out on patients who had documented preoperative weight before LSG (n=155) from the authors' institution between February 2008 to October 2017. Patients were grouped into two cohorts based on meeting the 5% target PrWL or not. The endpoint included percent postoperative weight loss (% PoWL) at one year and two to three years. Results A total of 155 individuals were identified and analysed. Of these patients, 78.7% of them (n=122) achieved the 5% target PrWL (target group) while 21.3% (n= 33) did not (non-target group). At one year, there was no statistical significant difference in the mean % PoWL between the non-target and target groups (22.3 ± 8.1% versus 19.4 ± 11.8% p value= 0.08). A similar observation was made at two-three years, where the mean % PoWL in the non-target group was 14.7 ± 10.7% versus 16.3 ± 14.4% in the target group (p value= 0.07). Our further analysis highlighted a statistically significant weak inversely proportional correlation between % PrWL and % PoWL at one year and two to three years. Conclusion Meeting target PrWL does not significantly impact on PoWL after LSG. Therefore, it should not serve as exclusion criteria for eligible patients who are in need of surgery.

Keywords: bariatric surgery; postoperative weight loss; preoperative weight loss; sleeve gastrectomy; target preoperative weight loss.

Figure 1. Number of patients and division into two cohorts based on meeting/not meeting the 5% PrWL target

Both cohorts were comparable in terms of weight and body mass index (BMI) at referral and surgery. The upper limit of the subject's age was similar but the youngest patient in the cohort who did not meet the 5% PrWL target was 32-years-old, as compared to the 26-years old-in the other cohort. PrWL: preoperative weight loss.

Figure 2. Average percentage of weight loss at one year (A) and two to three years (B) postoperatively

At one year postoperatively, non-target group % PoWL was 22.3 ±8.1% (n=92) vs target 19.4 ±11.8% (n=22) (p value= 0.08). At two to three years postoperatively, non-target % PoWL was 14.7 ±10.7% (n=55) vs target 16.3 ±14.4% (n=21) (p value= 0.07). PoWL: postoperative weight loss.

Figure 3. Graph showing correlation between % PrWL and % PoWL at one year in the cohort who met the 5% preoperative weight loss target

Weak inversely proportional relationship in the target group at one year postoperatively. PrWL: preoperative weight loss; PoWL: postoperative weight loss.

Figure 4. Graph showing correlation between % PrWL and % PoWL at two to three years for patients who met the 5% preoperative weight loss target

At two to three years, there was a maintained weak inversely proportional relationship between % PrWL and % PoWL. PrWL: preoperative weight loss; PoWL: postoperative weight loss.

Figure 5. Graph showing correlation between % PrWL and % PoWL at one year for patients who did not meet the 5% preoperative weight loss target

There was no correlation between % PrWL and % PoWL at one year postoperatively with r values closer to zero. PrWL: preoperative weight loss; PoWL: postoperative weight loss.

Figure 6. Graph showing correlation between % PrWL and % PoWL at two to three years for patients who did not meet the 5% preoperative weight loss target

The correlation observed in the non-target group at one year was maintained at two to three years. PrWL: preoperative weight loss; PoWL: postoperative weight loss.

Figure 7. Graph showing correlation between % PrWL and % PoWL at one year for all laparoscopic sleeve gastrectomy (LSG) patients

Analysing the correlation between % PrWL and % PoWL for all patients involved in the study showed a significant weak inversely proportional relationship at one year postoperatively (p value < 0.001). PrWL: preoperative weight loss; PoWL: postoperative weight loss.

Figure 8. Graph showing correlation between % PrWL and % PoWL at two to three years for all laparoscopic sleeve gastrectomy (LSG) patients

This statistically weak inversely proportional relationship was maintained at two to three years postoperatively (p value <0.001). PrWL: preoperative weight loss; PoWL: postoperative weight loss.