| dc.description.abstract | Introduction: The prevalence of morbid or class III obesity has increased in the last decades, and bariatric surgery represents an important therapeutic option for the treatment of severe forms of obesity, promoting a sustained medium and long-term weight loss. Comorbidities as arterial hypertension, diabetes mellitus, dyslipidemia, and hyperuricemia are frequently associated with morbid obesity and have an impact inmorbi-mortality of obese individuals. Mechanisms that contribute to weight loss and improvement of co-morbidities after bariatric surgeries are not completely elucidated. An important line of research is related to the influence of gastrointestinal peptides changes on body weight loss and maintenance after surgery. Bariatric operations are allowed by Brazilian Public Health System (SUS), set by specific indications criteria.Medium and long-term results of this treatment in populations operated on through SUS are not yet well-known. Thus, the objectives of this thesis are: i) to review medical literature concerning implications of different operations techniques in gastrointestinal peptides and their relationship with central regulation of appetite and satiety; ii) to describe socio-demographic and clinical profile of a morbidly obese cohort of SUS,submitted to gastric bypass at University Hospital of Federal University of Minas Gerais, starting from 1998; iii) to analyse the five years postoperative follow-up results of that cohort. Methods: This thesis will be submitted as four publications. For the first paper, medical articles published between 1970 and Mars 2006 were reviewed, with emphasis on last two years human experiments, that report different bariatric surgery techniques impact in anorexigenic and orexigenic gastrointestinal peptides. A search of the English, French or Portuguese-language literature was performed using MEDLINE's Database. Methodological aspects of each publication were analysed: study design; patient number and gender; follow-up; beyond the results. On the second article, baseline results of a cohort submitted to gastric bypass technique (Capellas surgery) at University Hospital of Federal University of Minas Gerais, between March 1998 and March 2005, werepresented. The characteristics of sample were described: distribution for gender; age; school time; occupation; anthropometric data; prevalence of arterial hypertension, diabetes mellitus, dyslipidemia, hyperuricemia, anemia and hypoproteinemia; use of antidepressant and anxyolitics medications; and mortality. Univariate analysis was used to explore the association of morbid obesity with interest variables. The third articlereported cohort results until December 2006: follow-up rates, anthropometric data and co-morbidities outcomes. The fourth publication, a letter to editor, discusses the results of a long-term Canadian cohort, in comparison to the ones of patients from University Hospital of Federal University of Minas Gerais. Results: FIRST PUBLICATION: Many are the peptides that could be involved in appetite and satiety control after the bariatric surgery: ghrelin, cholecystokinin, glucagon-like peptide-1, enteroglucagon, peptide YY, pancreatic polypeptide, gastric inhibitory polypeptide, orexyn. Most of the human experiments recently publishedanalyze the ghrelin and glucagon-like peptide-1. On evaluated 41 sectional and longitudinal studies, with a sample of eight to 66 patients, and several bariatric procedures: Roux-en-Y gastric bypass, adjustable gastric band, biliopancreatic diversion, jejuno-ileal bypass, and vertical banded gastroplasty. Peptides changes varied according to operations techniques, analytical methods and follow-up time. Studies related to ghrelin demonstrated since suppression, until the elevation of its prandial levels. Although there is evidence that gutbrain axis changes after bariatric surgery contributes to control body weight and improve co-morbidities, definitive conclusions cannot be drawn. SECOND PUBLICATION: Baseline cohort had 193 patients, with women's predominance (142 / 73.5%), school time higher than Brazilian media,elevated body mass index (BMI: 52.7 ± 8.1 kg/m2), and high prevalence of comorbidities: arterial hypertension (63.2%), diabetes mellitus (23.8%),hypercolesterolemia (41.6%), hypertrigliceridemia (45.2%), hyperuricemia (42.6%), anemia (5.2%), hypoproteinemia (3.6%). Moreover, the antidepressant and anxiolytics consumption was elevated. The one-year mortality was elevated in comparison with international average (4.1% versus lower than 1-2%), all deaths occurring until the 14ºpostoperative day. THIRD PUBLICATION: Follow-up rates were 91.9% on the first year, and 82.0%; 71.1%; 71.2%; 72.5% on the second, third, fourth and fifth years, respectively. Regarding the preoperative period there was an accentuated, persistent and significant reduction of BMI. The best results of weight loss were observed until the second year of follow- up. By this time, different criteria to analyze the success regarding the weight loss implied in diverse results, with success rates varying of 63.4% (Reinhold criteria) to 90.4% (percentage excess weight lost =50%). Between the second and the fifth year of follow-up, there was weight reacquisition of 8.1 ± 5.7 kg, what meant an significant reduction of excess weight lost (average difference: 8.5 ± 11.6; p=0.0001). There was important reduction of co-morbidities prevalence until the fifthyear of follow-up, despite partial weight regain. The anemia prevalence had a progressive increase along follow-up. FOURTH PUBLICATION: Postoperative weight loss results were very different from the ones of a long- term Canadian study, even considering higher superobesity prevalence at present cohort. Although observing great efficiency of the operation in high gravity patients, our success rates were worse thanthe international cohort ones. Conclusion: More researches are necessary for better comprehension of the gastrointestinal peptide alterations that, until this moment, were described in small clinical postoperative bariatric surgery studies, so that it could be correlated to the mechanisms that lead to body weight loss and co-morbidities resolution. That seems to be an important search field to assist in the development of new therapeutic obesity modalities. Gastric bypass was very efficient in medium-term follow- up to the cohort of University Hospital of Federal University of Minas Gerais, allowing impressive body weight reduction, and co-morbidities improvement during follow-up. Higherpostoperative mortality could be due to own characteristics of a population with elevated preoperative BMI and higher burden of co-morbidities. Sample size and follow-up loses are limiting factors of this study. The different results of this cohort, regarding other publications, could reflect socioeconomic and cultural environmentsinfluences. Significant increase of anemias prevalence exhibits the necessity of nutritional counseling and multivitamin supplementation to patients who have undergone bariatric surgery, especially in low income populations. | |
