Preoperative weight loss and postoperative short and long-term results in Bariatric Surgery

doi:10.21203/rs.3.rs-1964531/v1

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Preoperative weight loss and postoperative short and long-term results in Bariatric Surgery

https://doi.org/10.21203/rs.3.rs-1964531/v1

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Introduction

Change in lifestyle and diets is a part of the bariatric surgery process. Preoperative weight loss is still considered obligatory in some programs, but its benefits remain controversial. This study aimed to evaluate the influence of the preoperative weight loss on the postoperative results, in terms of long-term weight loss and perioperative morbidity.

Methods.

A retrospective review from the prospective collected database was performed. Patients operated for Roux-n-Y Gastric bypass (RYGB) or Sleeve Gastrectomy (SG) as a primary procedure with at least 5 years of follow-up were analysed. Two group of patients were defined depending on if any preoperative weight loss was achieved or not. Patients with 5% or more weight loss were independently evaluated too. Weight loss up to 5 years, nadir weight loss and early postoperative morbidity were analysed.

Results.

419 Patients were included (225 RYGB and 194 SG), 324 (77.3%) were women, with a mean age of 45.85 years (ranging 15 to 69). 178 patients (42.5%) achieved any weight loss prior to surgery, and just 26 (13.4%) more than 5%. Preoperative weight loss did not correlate with less morbidity, leak o reoperation rate after SG. In the RYGB preoperative weight loss patients showed a trend to higher morbidity.

In terms of weight loss, preoperative weight loss patients did not achieve better nadir BMI (27.99kg/m² vs 28.55kg/m², p=0.213) nor final BMI (31.56kg/m² vs 32.04kg/m², p=0.412). Those results were repeated when RYGB and SG patients were analysed independently.

Univariate and multivariate analyses did not find that PWL had any relationship to nadir BMI, final BMI nor postoperative morbidity, leak or reoperation risk.

Conclusions.

Preoperative weight loss did not correlate to better postoperative results nor to better weight loss results in our series.

Preoperative weight loss

long term results

morbidity

Bariatric surgery procedures are challenging both for the anthropometric characteristics of the patients and the complexity of the procedures themselves. Bariatric surgery process reaches much further than the operating room and the surgical procedure selection. Preoperative and postoperative management are also crucial.

During preoperative work-up, patients are recommended to introduce changes in their lifestyle as the first part of the treatment of obesity. Preoperative weight loss (PWL) has been considered one crucial part of this preoperative work-up. This weight loss has also been recommended and sometimes even considered obligatory to go to surgery. PWL has been related to better postoperative results, both in weight loss and less morbidity and mortality. Recently, specific preoperative diets have also been recommended for the enhanced recovery programs.

There is no consensus about the amount of weight required to proceed with a bariatric surgical procedure nor the goal of this weight loss nor the obligation to adhere to this preoperative weight loss programs.

Recent studies show controversial results (2) about the necessity and there are debates about the benefits of this PWL. The most recently updated clinical guidelines from American societies downgraded the recommendation of PWL(1). The same inconsistency was found when the reduction of morbidity was analyzed (5).

Given the heterogeneous literature, the purpose of this study was to evaluate PWL as a reliable predictor factor for postoperative weight loss at 5 years after surgery. We also aimed to appraise its relationship with postoperative complications.

A retrospective analysis from the prospectively collected database of bariatric surgery was performed. All cases were collected from a tertiary referral public hospital with high volume of bariatric surgery. The approval of the research ethics committee was obtained, not requiring any additional formal consent. All performed procedures were in accordance with the 1964 Helsinki declaration.

Patients who underwent SG or RYGB as a primary procedure and completed at least 5 years of follow-up were considered for analysis. Patients were followed-up every 3 months during the first year, every 6 months up to 2 years, and then on a yearly basis by their surgeon. Endocrinologists and nutritionists also performed a tailored follow-up. We excluded the patients lost during the follow-up and those converted to other surgical bariatric procedures.

All procedures were performed by experienced bariatric surgeons with at least 5 years of experience. All patients were preoperatively evaluated by a multidisciplinary team (MDT). Preoperative work-up included blood biochemical tests, abdominal sonography and upper esophagogastric endoscopy. Surgical procedure selection was done according to age, body mass index (BMI), preoperative examinations’ findings and patients’ preferencies. All indications were discussed by the MDT.

During preoperative evaluation, all patients were instructed in new lifestyle habits, changes in dietary patterns and recommendations in appropriate food selection. Just before surgery, PWL was encouraged with supervised diet. A very low-calorie diet was indicated for 7–10 days with a specific commercial preparation (700kCal per day). A specific amount of weight loss was not mandatory to proceed with surgery, but highly recommended. The only condition to deny or postpose surgery was weight regain.

Surgical technique for SG has been previously described elsewhere(2). We performed a 5-port laparoscopic RYGB with a 30cc pouch. We stablished a biliary limb of 75-100cm and Roux limb of 150cm, with lineal mechanic anastomoses and systematic closure of mesenteric defects. Postoperatively, both SG and RYGB patients followed our enhanced rehabilitation protocol for bariatric surgery, initiating oral intake within the first 24 hours, and were discharged 2–3 days after surgery if no incidences occurred.

We evaluated the BMI at every point of the follow-up up to 5 years after surgery and the nadir weight, postoperative morbidity, leak rate and mortality rate. Two groups were initially defined: patients who lost any weight loss and those who did not. A separate analysis was also performed to those patients who achieved 5% or more PWL.

Continuous variables were presented as mean and standard deviation or range. Categorical variables were presented as number of cases and percentage. Student’s t-test was used to compare continuous variables. A linear and logistic regression analysis was also performed. All the data were collected in an Excel datasheet and evaluated with SPSS v26.

419 patients met the inclusion criteria. Among them, 194 (46.3%) had received a SG, and 225 (53.7%) a RYGB. All patients had completed the 5-year follow-up. Globally, 324 (77.3%) were women. Medium age was 45.85 years (range 15–69). Medium preoperative BMI was 46.1 kg/m² for sleeve gastrectomy and 45.14 kg/m² for RYGB. Most common comorbidities found were obstructive sleep apnea (OSA) and high blood pressure (HTA). Other demographic data are summarized in Table 1.

Table 1

*Demographic data according to surgery*. SG: Sleeve Gastrectomy; RYGB: Roux-n-Y Gastric Bypass; BMI: Body Mass Index; T2DM: Type 2 Diabetes; HTA: Hypertension; OSA: Obstructive Sleep Apnea
	Overall (n = 419)	SG (n = 194)	RYGB (n = 225)	p
Female Sex (n, %)	324 (77.33%)	142 (73.2%)	182 (80.9%)	0.063
Age (mean, r)	45.85 (15–69)	44.59 (15–69)	46.93 (19–63)	0.019
Maximum Weight (kg,r)	123.22 (85–220)	125.8 (86.8–220)	121 (85–194)	0.012
Maximum BMI (kg/m², r)	46.42 (33.52–70.22)	47.03 (35.29–70.22)	45.9 (33.52–62.46)	0.043
Weight at surgery (kg, r)	120.99 (84–220)	123.29 (84–220)	119 (85–194)	0.023
BMI at surgery (kg/m², r)	45.59 (29.92–70.22)	46.1 (34.9-70.22)	45.14 (29.92–62.46)	0.440
T2DM (n, %)	123 (29.35%)	50 (25.8%)	73 (32.4%)	0.162
HTA (n, %)	203 (48.45%)	97 (50%)	106 (47.1%)	0.558
Dyslipidaemia (n, %)	175 (41.77%)	84 (43.3%)	91 (40.4%)	0.619
OSA (n, %)	290 (69.2%)	130 (67%)	160 (71.1%)	0.396
Morbidity (n, %)	41 (9.79%)	13 (6.8%)	28 (12.6%)	0.068
Reoperation (n, %)	24 (5.73%)	8 (4.2%)	16 (7.2%)	0.213

There were 178 patients (42.5%) that lost any weight prior to surgery, 82 (42.3%) from the SG group and 96 (42.7%) form RYGB group. Mean loss for both groups was 2.5kg and 2kg, respectively. Only 50 patients (11.9%) achieved a PWL superior to 5%, 26 (13.4%) from the SG group and 24 (10.7%) from the RYGB group.

No relationship between PWL and the rate of morbidity, leak or reoperation for SG patients was found. Among RYGB patients, on the other hand, those who lost some weight showed a trend to higher morbidity, although without reaching statistical significance. Those who lost 5% of weight or more, were found to have a higher leak rate (12.5% vs 2%, p < 0.05) (Table 2). There was no mortality in our series.

In the overall series (Fig. 1), losing any weight prior to surgery did not correlate with any differences in nadir BMI (27.99 vs 28.55, p = 0.213) nor in BMI after 5 years (31.56 vs 32.04, p = 0.412). Those differences were also not seen when we looked at SG and RYGB patients separately. In the SG group, nadir BMI was 28.27 vs 29.62 (p = 0.06) and at 5 years 32.38 vs 33.83 (p = 0.09). RYGB patients behaved similarly at nadir (27.77 vs 27.64, p = 0.818) and after 5 years (30.95 vs 30.47, p = 0.484).

When we looked at those patients who achieved a minimum of 5% of PWL (Fig. 2), our data showed differences on nadir BMI in the RYGB patients (26.92 vs 28.56; p = 0.018). However, no differences on BMI after 5 years of surgery were found (30.60 vs 31.99; p = 0.13). Among SG patients, PWL > 5% was related to lower nadir BMI (26.18 vs 29.5; p = 0.001) and lower BMI after 5 years of surgery (30.34 vs 33.61; p = 0.013).

Table 2

*Morbidity, leak, and reoperation rate according to surgery and weight loss.* PWL: Preoperative Weight Loss
	SG (n = 194)
	PWL > 0% (n = 82)	PWL = 0% (n = 112)	p	PWL > 0% (n = 96)	PWL = 0% (n = 129)	p
Morbidity	8 (10%)	5 (4.5%)	0.231	15 (16%)	13 (10.1%)	0.27
Leak	2 (2.5%)	3 (2.7%)	1	5 (5.3%)	2 (1.6%)	0.135
Reoperation	4 (5%)	4 (3.6%)	0.722	9 (9.6%)	7 (5.4%)	0.356
	PWL > 5% (n = 26)	PWL ≤ 5% (n = 168)	p	PWL > 5% (n = 24)	PWL ≤ 5% (n = 201)	p
Morbidity	1 (3.8%)	12 (7.3%)	1	4 (16.7%)	24 (12.1%)	0.516
Leak	0	5 (3%)	1	3 (12.5%)	4 (2%)	0.029
Reoperation	1 (3.8%)	7 (4.2%)	1	4 (16.7%)	12 (6%)	0.78

Linear regression analysis to predict BMI at 5 years did not show any statistically significance at neither univariate nor multivariate analysis. Preoperative variables like age and BMI at surgery were the only variables that predicted final BMI in the SG group. In RYGB, postoperative morbidity was also a predictor for worse weight loss. Logistic regression models were also calculated to predict risk for morbidity, leak and reoperation. None of the models for SG considered PWL as a predictive factor for reduced or increased risk of any complication. Same results were found for RYGB patients.

According to our results, in our series 42.5% of patients achieved some preoperative weight loss, and just in 11.9% of them was higher than 5%. Preoperative weight loss did not reduce the rate of morbidity, leak or reoperation for SG patients, while in RYGB it might have had a negative influence.

There is no consensus on literature about the recommendation of losing weight prior to surgery and which amount of it should be requested(3). Stefura et al.(4) recommended preoperative weight loss, they observed that patients who lost more than 5% preoperatively got a superior postoperative weight loss. Hutcheon et al.(5) also found that patients who followed a 4 weeks low calorie diet and achieved a preoperative weight loss of more than 8% not only had a better postoperative percentage of excess weight loss (%EWL) over 1 year but also a shorter hospital stay. It was also recommended by Alvarado et al.(6), who found that preoperative weight loss of more than 5% in RYGB patients was associated with higher postoperative weight loss 1 year after surgery and shorter operative time, with no influence on comorbidities or complications. Santo et al.(3) also recommended it for superobese patients. These results could be explained by a higher motivation of the patients to follow a postoperative healthy lifestyle.

However, other authors found opposite results. Abishek et al.(7) could not find increased postoperative weight loss at 1 year in patients with SG and preoperative weight loss. Neither did Raman et al.(8), or Watanabe et al.(9), who found differences on total weight loss (TWL) over 1 year but not on overall TWL.

Likewise in our series, the systematic review from Ochner et al.(10) concluded there is insufficient evidence to stablish a minimum preoperative weight loss as a must for bariatric surgery, and it should not condemn those who do not achieve the goal ineligible to receive a surgical procedure. These dissimilar results could be explained because of the high heterogeneity of literature (Table 3). More recent publications that suggested that preoperative weight loss was not a predictor factor for postoperative BMI.

Table 3

Summary of the majority of the literature and their findings. Includes number of patients, length of follow-up registered, variables included such as BMI, TWL, EWL, and percentage of preoperative weight loss and complications. Includes conclusions and type of article. SG: sleeve. RYGBP: Roux-n-Y gastric bypass. RCT: randomized controlled trial.
Author, year	Patients	Type of Study	Follow-up	Procedure	PWL > 5%	PWL > 10%	Complications	Results
Cottam 2019	12406	Systematic review		SG				PWL as a predictor
Stefura 2019	909	Observational	6m	SG, RYGB	X			PWL as a predictor
Raman 2018	218	Observational	1y	SG, RYGB				No predictor
Abhishek 2018	192	Observational	1y	SG	X			No predictor
Roman 2018	6060	Meta-analysis		SG, RYGB			X	No predictor
Hutcheon 2018	355	Observational	1y	SG, RYGB				PWL as a predictor
Tewksbury 2017		Review		SG, RYGB			X	No predictor
Watanabe 2017	247	Observational	1y	SG	X		X	PWL as a predictor
Kim 2017		Review		SG, RYGB				No predictor
Kalarchian 2016	143	RCT	1y	SG, RYGB			X	No predictor
Anderin 2015	22327	Observational	6w	RYGB			X	PWL as a predictor
Gerber 2014	35519	Systematic review		SG, RYGB			X	No predictor
Santo 2014	20	Observational	14w	RYGB				No predictor
Ochner 2012	2618	Systematic review		RYGB		X		No predictor
Van Nieuwenhove 2011	273	RCT	1m	RYGB			X	No predictor
Livhits 2009	3404	Systematic review		SG, RYGB		X		PWL as a predictor
Bushr 2008	146	Observational	2y	SG, RYGB			X	No predictor
Alami RS 2007	61	RCT	1y	RYGB		X	X	PWL as a predictor
Still 2007	884	Observational	12m	RYGB	X	X		PWL as a predictor
Alvarado 2005	90	Observational	1y	RYGB			X	PWL as a predictor

Correlation between the degree of weight lost and the risk of complications was not found neither, except for leakage in RYGB patients. This could be explained by patient heterogeneity in this group, higher technical complexity or maybe by some preoperatively under-detected malnourished patients in this group. Those results should be carefully interpreted since they come from a small sample of patients.

Regarding complications, Anderin et al.(11) studied RYGB patients and found that preoperative weight loss was associated with lower relative risk for conversion and lower risk for complications within 6 weeks after surgery, except for bleeding. Alami et al.(12) in a RCT could not demonstrate any reduction of overall complications. Same results were reported in other publications (5, 17, 18). Howbeit, those results should be carefully analysed due to the non-randomized studies included, limited number of patients and the low frequency of postoperative complications. Additionally, scarce literature is about SG patients since most of reports mainly include RYGB.

A strong point of this series comes from a longer-term follow-up than most of the literature published until now. The retrospective nature of the analysis is a strong limitation. It is also a single-centre series. It is noted the short percentage of patients in our database who completed a 5 years follow-up. Other limitation, defined as well in methodology, is the long period permitted for preoperative weight loss, up to 6 months in some cases. Finally, patients’ heterogeneity is also a bias that may have negatively influenced our findings.

Preoperative weight loss might have a minor influence on nadir weight, but at long term, it only affected to those patients who underwent a sleeve gastrectomy. We did not find any correlation to postoperative morbidity neither. Further high-quality and adequately powered prospective trials are needed to evaluate preoperative weight-loss diets on postoperative outcomes.

Funding disclosure: This work has not been financed through any grant, scholarship or contribution of any kind.

Disclosures: Authors have no conflicts of interest or financial ties to disclose.

Author Contributions

Mireia Verdaguer MD^a
1. Acquisition of data
2. Analysis and interpretation of data
3. Drafting of manuscript
Marc Beisani MD, PhD^b
1. Study conception and design
2. Analysis and interpretation of data
3. Critical revision of manuscript
Óscar González López MD, PhD^a
1. Study conception and design
2. Critical revision of manuscript
Ramón Vilallonga MD, PhD^a, FACS
1. Critical revision of manuscript
Amador García Ruiz de Gordejuela MD, PhD^a, FACS^*
1. Study conception and design
2. Analysis and interpretation of data
3. Drafting of manuscript
Maria José Gómez Jurado MD^a
1. Acquisition of data
2. Critical revision of manuscript
Anna Curell MD^c
1. Acquisition of data
2. Critical revision of manuscript
Manel Armengol Carrasco MD, PhD^a
1. Critical revision of manuscript

Mechanick JI, Apovian C, Brethauer S, Garvey WT, Joffe AM, Kim J, et al. Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures – 2019 update: cosponsored by American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society for Metabolic & Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists. Surg Obes Relat Dis. 2020;16(2):175–247.
Vilallonga R, Hidalgo M, Garcia Ruiz de Gordejuela A, Caubet E, Gonzalez O, Ciudin A, et al. Operative and Postoperative Complications of Laparoscopic Sleeve Gastrectomy in Super and Nonsuper Obese Patients: A Center of Excellence Experience Comparative Study. J Laparoendosc Adv Surg Tech A. 2020;30(5):501–7.
Santo MA, Riccioppo D, Pajecki D, Cleva R, Kawamoto F, Cecconello I. Preoperative weight loss in super-obese patients: study of the rate of weight loss and its effects on surgical morbidity. Clinics (Sao Paulo). 2014;69(12):828–34.
Stefura T, Dros J, Kacprzyk A, Wierdak M, Proczko-Stepaniak M, Szymanski M, et al. Influence of Preoperative Weight Loss on Outcomes of Bariatric Surgery for Patients Under the Enhanced Recovery After Surgery Protocol. Obes Surg. 2019;29(4):1134–41.
Hutcheon DA, Hale AL, Ewing JA, Miller M, Couto F, Bour ES, et al. Short-Term Preoperative Weight Loss and Postoperative Outcomes in Bariatric Surgery. J Am Coll Surg. 2018;226(4):514–24.
Alvarado R, Alami RS, Hsu G, Safadi BY, Sanchez BR, Morton JM, et al. The impact of preoperative weight loss in patients undergoing laparoscopic Roux-en-Y gastric bypass. Obes Surg. 2005;15(9):1282–6.
Parmar AD, Drosdeck JM, Mattar SG, Spight D, Husain FA. Impact of Preoperative Weight Loss on Postoperative Weight Loss After Sleeve Gastrectomy. Bariatric Surgical Practice and Patient Care. 2018;13(2):69–74.
Krimpuri RD, Yokley JM, Seeholzer EL, Horwath EL, Thomas CL, Bardaro SJ. Qualifying for bariatric surgery: is preoperative weight loss a reliable predictor of postoperative weight loss? Surg Obes Relat Dis. 2018;14(1):60–4.
Watanabe A, Seki Y, Haruta H, Kikkawa E, Kasama K. Preoperative Weight Loss and Operative Outcome After Laparoscopic Sleeve Gastrectomy. Obes Surg. 2017;27(10):2515–21.
Ochner CN, Dambkowski CL, Yeomans BL, Teixeira J, Xavier Pi-Sunyer F. Pre-bariatric surgery weight loss requirements and the effect of preoperative weight loss on postoperative outcome. Int J Obes (Lond). 2012;36(11):1380–7.
Anderin C, Gustafsson UO, Heijbel N, Thorell A. Weight loss before bariatric surgery and postoperative complications: data from the Scandinavian Obesity Registry (SOReg). Ann Surg. 2015;261(5):909–13.
Alami RS, Morton JM, Schuster R, Lie J, Sanchez BR, Peters A, et al. Is there a benefit to preoperative weight loss in gastric bypass patients? A prospective randomized trial. Surg Obes Relat Dis. 2007;3(2):141–5; discussion 5–6.

No competing interests reported.

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Preoperative weight loss and postoperative short and long-term results in Bariatric Surgery

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