The effect of bariatric surgery on metabolic syndrome: A retrospective cohort study in Colombia

Abstract Introduction and Objective Metabolic syndrome (MetS) represents a group of metabolic abnormalities. It is currently a pandemic, and its prevalence is on the rise. MetS has a direct relationship with obesity, for this reason, bariatric and metabolic surgery has been proposed as a method to simultaneously control obesity and MetS. However, in Colombia the results of this intervention are unknown. This study aims to compare metabolic syndrome before and after bariatric surgery in a Colombian population. Methods Retrospective cohort study conducted in a highly complex institution in Colombia, where comparing the prevalence of metabolic syndrome in patients who underwent bariatric surgery during a 1‐year follow‐up period, between January 2015 and December 2019. Of these patients, 48 underwent Roux‐en‐Y gastric bypass, and 32 underwent sleeve gastrectomy by laparoscopic technique. Results A total of 80 patients were included, of which 67.5% were women and the mean age was 42.8 ± 12.9 years. The most frequent preprocedure comorbidities were arterial hypertension (36.2%), dyslipidemia (32.4%), and sleep apnea (20%). After bariatric surgery, the prevalence of metabolic syndrome decreased from 66.2% to 3.7% (p < 0.05). In addition, a reduction in the Homeostatic Model Assessment for Insulin Resistance score from 77.5% to 22.5% was observed during the follow‐up period. HbA1c, creatinine, and thyroid‐stimulating hormone, were the only parameters without significant changes. Conclusions Metabolic and bariatric surgery is an effective treatment for weight reduction, with a high impact in reducing the prevalence of metabolic syndrome and insulin resistance in the short and medium term in the Colombian population.


| INTRODUCTION
Metabolic Syndrome (MetS) represents a group of metabolic abnormalities including arterial hypertension, central obesity, insulin resistance (IR), atherogenic dyslipidemia among others. It is strongly associated with obesity; however, it is not always synonymous with MetS. 1 The MetS is currently a pandemic; its prevalence varies worldwide and often corresponds to the prevalence of obesity. MetS affects an estimated 150 million people in Europe and 65 million in the United States, Southeast Asia has a prevalence of 22.9%. 2

In Latin
America, MetS has a prevalence of 15% in people over 20 years of age. 3 In Colombia, it has been estimated that the urban prevalence of MetS among men and women is 9% and 19%, respectively. 4 Pinzón et al., 5 in 2007 estimated that the prevalence of MetS in an adult population of the city of Bucaramanga was 12.3% according to the Adult Treatment Panel III (ATP III) classification and 32.9% with the classification of the IDF. Since then, this phenomenon has not been studied again. 2,6 The MetS has a strong relationship with obesity, a pathology with high prevalence in the world and difficult to manage. 7 In the last decade, increasing economic resources have been directed to develop new strategies that can control the rise in prevalence of obesity, however, the established goals have not been met. 8 There are multiple treatments proposed for the management of MetS, from the increase in physical activity, to pharmacological management, even so, in many cases a weight loss of more than 10% is not achieved, and those who manage to lose weight, on multiple occasions recover the weight lost quickly. 9 Currently, Metabolic and Bariatric Surgery (MBS) is the indicated treatment for obesity when other measures have failed, since it is a safe and effective procedure, additionally it is supported by multiple academic consensuses and the National Institute of Health of the United States. 10 However, there is a paucity of literature on the effect of bariatric surgery on the MetS. In Colombia, the results of this intervention are unknown.
This study aims to compare metabolic syndrome (specific objectives of clinical parameters) before and after bariatric surgery in a Colombian population.

| Study design and patient selection
The reporting of this study conforms to the STROBE guidelines. 11 Retrospective cohort study of anonymized secondary data, whose follow-up begins from the indication of the surgical procedure to 1 year postoperatively. A population of patients undergoing MBS was taken from a highly complex institution specialized in bariatric surgery in the city of Bucaramanga and its metropolitan area, Colombia, between January 2015 and December 2019.

| Statistical analysis
A descriptive analysis was performed using the mean and standard deviation for continuous variables (all continuous variables had a normal distribution evaluated by the Shapiro-Wilk test), categorical variables were described by absolute frequencies and relative frequencies. A bivariate analysis was performed comparing the presurgical and postsurgical values (per year), the continuous variables were compared using a paired mean difference test, the categorical variables were compared by a test of differences of paired proportions. A p < 0.05 was defined as statistical significance. All analyses were performed using stata 15.0.

| Ethical statements
It is an observational project based on anonymized secondary data. This study was reviewed and approved by the Ethics Committee of the Universidad Autónoma de Bucaramanga (no.

| RESULTS
During the period from January 2015 to December 2019, 209 MBS were carried out. After applying the inclusion and exclusion criteria, 80 patients were included. Of the total participants, 54 (67.5%) were women and the mean age of the population was 42.8 ± 12.9 years.
All variables were evaluated pre-procedure and after 1 year of the surgical procedure, the vast majority had a statistically significant decrease, except HbA1c, creatinine, and TSH (Table 2). HbA1c was not statistically significant since there were values in extreme ranges that could affect this significance.
However, a wide change in the mean HbA1c pre-and postprocedure can be noted. None of the patients who participated in the study had a history of kidney disease or altered preprocedure creatinine values, which is why there were no significant changes after the procedure, it should be emphasized that there was no alteration of the same, which reflects that the procedure is not a risk factor for kidney failure.
Regarding MetS, its pre-procedure prevalence was 66.2%, with a statistically significant decrease (p < 0.05) of 94.4%. This means that the prevalence of MetS 1 year after the procedure was only 3.7%.
There was a greater number of patients with MetS in the LRYGB type procedure. In the same way, a discrimination by gender was made, which showed that there is a higher prevalence in the female sex (41.2%) and that this value is reduced to only 2.5% after the procedure (Table 3).   The most performed MBS procedure in Colombia is the LRYGB, followed by the SGIT. LRYGB is a mixed procedure, since it has the restrictive and poorly absorbed component, 26,27 this procedure shows adequate levels of safety. The risk of dying from surgery is <0.2% and the risk of serious complications such as bleeding, infections and thromboembolism is less than 5%. 28 SGIT is a purely restrictive procedure, and the risk of complications and death are similar to that of LRYGB. 29 Currently, one of the recommended procedures for the patient with obesity and MetS in whom conservative treatment has failed is LRYGB, since when the anatomical structure of the gastrointestinal tract is modified, the capacity of the stomach decreases and prevents the passage of food through the duodenum and proximal jejunum, decreasing the percentage of absorption of lipids and carbohydrates, impacting on a rapid, effective, and long-term loss of weight. 30 Although SGIT is not the ideal surgery for MetS, in our study the pre-procedure prevalence was 25% and 1 year after the procedure it decreased to 2.5%, showing that it also has an important effect in reducing MetS. Our data were consistent with the available literature; however, it is important to clarify that as it is a purely restrictive procedure, its effect is not as effective as mixed or malabsorptive procedures. 31 The