Impact of Roux-en-Y Gastric Bypass and Vertical Gastrectomy on weight loss: a retrospective and longitudinal study in the State of Paraná, Brazil

ABSTRACT Aim: to compare the impact of Roux’s Y Gastric Bypass (RYGB) and Sleeve Gastrectomy (SG) techniques on body weight reduction over 1 and 5 years after bariatric surgery in obese patients in the state of Paraná. Methods: longitudinal and retrospective study, conducted between January 2010 and December 2013, with 737 patients of both sexes submitted to RYGB or SG and evaluated in the preoperative, 1 and 5 years after bariatric surgery (BS). Age, height, body weight, Body Mass Index (BMI), biochemical and pressure parameters were recorded. Results: of the total of patients, men represented lower frequency, were slightly older, with higher body weight, BMI and worse metabolic and pressure conditions than women in pre-BS (p<0.05). Regardless of sex, RYGB and SG were effective in promoting body weight reduction and BMI in 1 and 5 years after BS; the RYGB technique had greater impact on these variables in both sexes (p<0.05). The highest percentage of lost weight was observed in women who underwent the RYGB technique in the first year after BS. Five years after BS, the RYGB technique promoted a higher rate of body weight reduction in men and women compared to the SG technique (p<0.05). Conclusion: regardless of sex, the RYGB technique promotes a higher degree of body weight reduction and BMI over time compared to the SG; having its biggest impacts in the 1 year after BS, especially in women.

Body Mass Index (BMI) ≥40Kg/m 2 , may affect 6% of men and 8% of women worldwide 1 .In Brazil, data recorded by the Food and Nutrition Surveillance System (SISVAN) of the Ministry of Health showed that in 2019, more than 65% of the Brazilian adult population was above adequate body weight.Of these, more than 3% have grade III obesity, that is, BMI ≥40Kg/m 2 , a prerequisite for bariatric surgery (BS).In the State of Paraná, almost 70% of the adult population is overweight and more than 4% of these individuals are considered obese grade III 2 .
The excessive accumulation of white adipose tissue (WAT), typical of obese individuals, is linked to a chronic pro-inflammatory condition, which reduces the action of insulin and causes glucose intolerance, dyslipidemia, and arterial hypertension, factors comprising the so-called Metabolic Syndrome (MS).
expenditures in the Unified Health System (SUS) are related to (NCDs), especially diabetes and CVD, a situation that is reflected in Paraná 2,4 .Therefore, the search for strategies that enable the reduction of WAT and promote the restoration of glycemic and lipid homeostasis and cardiovascular health are fundamental to guarantee the quality of life of these patients and to avoid the onset of NCDs 5 .In this context, BS is capable of promoting, in addition to significant, rapid, and sustainable weight loss, improvement in glycemic control, dyslipidemia, normalizing blood pressure, and reducing the risks of CVD and diabetes 6,7 .
Every year, around 635,000 BSs are performed worldwide.Brazil ranks second in the number of BSs performed and has the largest number of bariatric surgeons in the world, followed by the United States.
Between 2003 and 2018, the number of BSs performed in Brazil increased more than sixfold [8][9][10] .According to Marchesini, in 2021 Brazil had 4.9 million people eligible for BS, of whom more than 210 thousand are in the State of Paraná.It is important to emphasize that in Brazil, more than 90% of BSs are performed by private health services [11][12][13] .
Roux-en-Y Gastric Bypass (RYGB) and Sleeve Gastrectomy (SG) are the two most commonly performed BS techniques worldwide 14 .RYGB corresponds to 75% of BSs performed in Brazil and is considered the gold standard for weight loss and restoration of glycemic homeostasis.SG is considered a simpler technique, with fewer late complications, such as hernias and ulcerations, and less impact on the absorption of nutrients, such as iron, calcium and vitamins, which may explain the preference for this technique in some countries, such as the United States, Scotland, and Germany 9,[13][14][15] .
As pointed out by 2018 data from the Federation for the Surgery of Obesity and Metabolic Disorders (IFSO), Brazil still does not have a consolidated national system for registering BS, and among the 51 countries that participated in the study, it is one of those that did not provide complete information on the profile of patients undergoing BS.Only one hospital in the capital of Paraná participated in the IFSO 2018 records 8 .Additionally, there are few Brazilian studies comparing the long-term impact of SG and RYGB techniques, mainly with regard to BMI reduction, weight loss, and gender influence 10,16 .Therefore, the expansion of national publications on the effects of BS, especially in the long term, has significant relevance for the follow-up and management of these patients.
Thus, in the present study, we compared the impact of RYGB and SG techniques on body weight loss and BMI reduction over one and five years after BS, considering the influence of sex.

METHODS
The present study is a longitudinal and retrospective one, in which data were collected from the medical records of 737 patients of both sexes, who underwent RYGB or SG in a private hospital in Western  homoscedasticity (Cochran Test), followed by association analysis using the T-Test for unpaired samples.
When the assumptions of normality and homoscedasticity were not accepted, the Mann-Whitney U Test was applied.To assess the existence of an association between the different variables, the PERMANOVA Test was applied.Statistical analyzes were performed using XLStat Version 19.4 (ADDINSOFT, 2018) and the R computational program (R Development Core Team, 2019).We adopted p<0.05 as a significance criterion in all analyses.

RESULTS
Of the patients undergoing BS, 589 (80%) underwent RYGB and 148 (20%) SG.The profile of obese patients before BS is shown in Table 1.The mean age of women was 39.3 years, slightly lower than men (p<0.0001).Furthermore, as a consequence of sexual dimorphism, women had lower body weight and height compared with men (p<0.0001).However, men had higher BMI values than women (p<0.0001).
We observed no significant differences in blood glucose and LDL concentrations between sexes (p>0.05).
However, plasma triglyceride levels were significantly higher in men (p=0.007).
In contrast, total and HDL cholesterol values were elevated in women compared with men.Males had higher DBP and SBP values compared with females (Table 1; p<0.0001).The influence of BS on body weight and BMI in men and women over time is shown in Figure 1.BMI was significantly influenced by the time factor (F=255.7; p=0.000), but not by the sex factor (F=0.9; p=0.405).
Thus, for both sexes, we observed a significant reduction in BMI at one and five years after BS, with a more pronounced drop in the first year after BS (Figure 1A).
In contrast, body weight was influenced by sex (F=55.3;p=0.000) and time (F=803.7;p=0.000), but without interaction (F=2.6;p=0.075).Thus, women have lower body weight over time compared with men.In both sexes, we found a marked loss of body weight one year after BS, which was relatively preserved five years after BS (Figure 1B).  Figure 2 shows the comparative effect between the RYGB and SG techniques on BMI and body weight.
The type of surgical technique significantly influences the magnitude of the decrease in body weight (F=20.8,p=0.000) and the reduction in BMI (F=7.6, p=0.007).
The time factor also significant influences body weight (F=563.7;p=0.000) and BMI (F=188.5;p=0.000), without interaction between the factors.In this sense, RYGB promoted a greater degree of reduction in BMI (Figure 2A) and body weight (Figure 2B) compared with SG.
One year after RYGB and SG, patients showed a marked reduction in BMI and body weight compared with the period before BS, the effect being relatively preserved after five years.
Finally, we compared the percentage of weight lost at one and five years after BS, considering type of technique and sex (Figure 3).We found that one year after BS, women undergoing RYGB showed a higher percentage of weight loss compared with women and men undergoing SG.In addition, five years after BS, women and men undergoing RYGB maintained a higher percentage of weight loss compared with those undergoing SG.In contrast to Brazil, ISFO world records (2018) indicated that in the last two years there have been increases in SG in relation to RYGB in many countries 8 .

DISCUSSION
The age profile and BMI values observed in our patients in the pre-BS period were also similar to other national and international studies 21,22 .
Considering pre-BS data, men had higher BMI values and a greater presence of glycemic, lipid, and blood pressure alterations compared with women.Obesity reduces male testosterone levels, a factor that is related to a higher incidence of atherosclerosis, hypertension, hyperinsulinemia, dyslipidemia, and diabetes [23][24][25] .These findings indicate the need for greater attention to the health condition of the male population of Paraná, especially the obese.
The benefits of BS for health are widely recognized, especially in morbidly obese individuals, in whom there is a significant reduction in body weight and adiposity and improvement in glycemic, lipid, and Gamba Impact of Roux-en-Y Gastric Bypass and Vertical Gastrectomy on weight loss: a retrospective and longitudinal study in the State of Paraná, Brazil blood pressure control 26 .Our findings confirm these, as regardless of gender, in both techniques (RYGB and SG) there was a significant reduction in body weight and BMI over time, especially in the first year after BS.We could not evaluate metabolic and blood pressure aspects over time, confirming the need to expand long-term records, an aspect also highlighted by the IFSO 2018 records 8 .
A recent Brazilian study carried out by Schiavon et al.
(2020) showed that RYGB was effective in controlling blood pressure in men and women three years after BS 27 .
Similarly, a recent retrospective study with more than 5,000 patients undergoing BS showed that RYGB and SG are effective in promoting diabetes remission, the former displaying better results 28 .Other studies found no differences in terms of weight reduction between RYGB and SG one year after BS 29,30 .
On the other hand, a metanalysis performed by Li et Sex is a determining factor in metabolism and responses to weight reduction procedures 33 .In the first year after BS, we found the highest rate of weight loss in women undergoing RYGB, confirming the study by Olbers et al. (2006), who showed a greater reduction in visceral WAT in women after RYGB compared with women who underwent SG 34 .Korner et al. (2008)   found no difference in the reduction of visceral WAT in men with RYGB and the control group 35 .
Five years after BS, our findings reveal that, regardless of sex, RYGB promotes greater weight loss compared with SG, confirming the greater efficacy Paraná from January 2010 to December 2013.The Ethics in Human Research Committee of the State University of Western Paraná (UNIOESTE-CAAE) approved this study under protocol number 80388317.2.0000.0107,following the criteria previously established by Ordinance 425 of the Brazilian Ministry of Health 17 .The sampled patients were between 18 and 65 years old, with BMI ≥40Kg/m 2 , or BMI >35Kg/m 2 associated with two or more comorbidities and clinical treatment failures conducted for more than two years.Both surgical procedures, RYGB and SG, were performed by the same surgical team and with the same techniques.Of the 737 patients, we recorded sex (male or female), age (years), height (m), body weight (Kg), and BMI (Kg/m 2 ), obtained in three moments: before BS, one year, and five years after BS.When present, in the pre-BS we also recorded Systolic (SBP; mmHg) and diastolic (DBP; mmHg) blood pressure values, as well as plasmatic biochemical values (mg/dL) of glucose, triglycerides, total cholesterol, HDL, and LDL.These data were categorized as Adequate or Altered according to the recommendations of the Federal Council of Medicine.The respective numbers for these data are indicated in the tables.Body weight and BMI values were evaluated pre-BS and one and five years after BS, comparing the effects of the RYGB and SG techniques, as well as the influence of sex.The data obtained were tabulated in Microsoft Excel ® spreadsheets and submitted to statistical assumptions of normality (Shapiro-Wilk Test) and

Figure 1 .
Figure 1.Changes in BMI and body weight induced by BS in women and men over time.Data are mean and confidence interval (95% CI).

Figure 2 .
Figure 2. Comparative effects of changes in BMI and body weight induced by RYGB and SG.Data are means and confidence intervals (95% CI).
Paraná is the state in which most BSs are performed in Brazil, the majority in private hospitals and whose impacts on health, especially in the long term, are little known.Therefore, our study presents unpublished data regarding the impact of RYGB and SG techniques on weight loss and BMI of obese patients from Paraná, over one and five years.RYGB and SG procedures represent almost 85% of all BSs in the world, with frequencies varying according to different countries 8,9,15 .In our sample, more than 80% of patients underwent RYGB, the majority of patients being female, confirming data previously published in other regions of Brazil and the world9,18-20.

Figure 3 .
Figure 3. Percentage of weight lost at one and 5 years after different types of BS in men and women.Data are mean and confidence interval (95% CI).
al. (2016) showed a higher percentage of weight lost in patients undergoing RYGB compared with patients undergoing SG 31 , corroborating our findings.Hayoz et al., in 2018, emphasized that studies on BS with five years of follow-up are scarce, making it difficult to analyze the durability of these effects 32 .Therefore, the results of the relative maintenance of the effects of weight loss and BMI five years after BS are unprecedented for this population and reveal a longerlasting effect promoted by the RYGB technique.

Table 1 -
Anthropometric data, blood pressure, and plasma biochemical parameters in pre-BS women and men.
#Data expressed as mean ± SD; Student's t-test p-value or mean and interquartile range [1Q and 3Q]; #p-value Mann-Whitney U.

Table 2
GambaImpact of Roux-en-Y Gastric Bypass and Vertical Gastrectomy on weight loss: a retrospective and longitudinal study in the State of Paraná, Brazil

Table 2 -
Categorization of clinical and biochemical variables in pre-BS women and men.
*Chi-square test of independence; AF: absolute frequency; RF: relative frequency.Gamba Impact of Roux-en-Y Gastric Bypass and Vertical Gastrectomy on weight loss: a retrospective and longitudinal study in the State of Paraná, Brazil