Phase angle and non-alcoholic fatty liver disease before and after bariatric surgery

Abstract

BACKGROUND Obesity is a global health problem that is continuing to increase in the young population. In Brazil, the frequency of obesity in 2018 was 19.8%. Several comorbidities are directly associated with obesity, such as non-alcoholic fatty liver disease (NAFLD), which is considered the most common liver disorder in Western countries and affects up to 46% of adults. Bariatric surgery is effective in treating obesity and can improve NAFLD; however, the effect of bariatric surgery on body composition, phase angle (PA), and improving NAFLD needs to be further studied. AIM To analyze the PA in the postoperative period of bariatric surgery and to correlate it with changes in body composition and liver disease. METHODS This study is a retrospective cohort study of the analysis of the medical records of patients undergoing bariatric surgery in a reference center of a teaching hospital in Porto Alegre over a 2-year period. Patients older than 18 years whose record contained all information relevant to the study were included. The data analyzed were body composition and PA through electrical bioimpedance and NAFLD through liver biopsy in the pre- and postoperative period. The level of significance adopted for the statistical analyses was 5%. RESULTS We evaluated 379 patients with preoperative data. Regarding PA, 169 patients were analyzed, and 33 patients had liver biopsy pre- and postoperatively with NAFLD information. In total, 79.4% were female, with a mean age of 39.1 ± 10.6 years. The average body mass index (BMI) was 45.9 ± 7.5 kg/m². The PA showed a mean of 5.8 ± 0.62° in the preoperative period and a significant reduction in the postoperative period. A postoperative reduction in body composition data (skeletal muscle mass, fat percentage, fat mass, body cell mass, BMI and visceral fat area) was shown as well. Regarding liver disease, all patients presented a reduction in the degrees and stages of liver disease in the postoperative period, and some had no degree of liver disease at all. CONCLUSION PA decreased after bariatric surgery, with a direct correlation with weight loss and changes in body composition. The decrease in PA was not correlated with the improvement in NAFLD.

Bioelectrical impedance (BIA)-derived phase angle in adults with obesity: A systematic review

“…The greatest decrease in PhA values was observed in patients with the highest loss of body weight following RYGB or LSG either after 24 months [37] or after 6 months [35,36]. The study by Teixeira et al [42] was the only one that performed segmental BIA showing reduced PhA values for both whole-body, upper (À13 % right, À16 % left) and lower limbs (À17 % right À17 % left). In one paper, compared to surgery, PhA increased after one year of a multidisciplinary, nonsurgical intervention program with a low-energy diet [33].…”

“…At baseline, a number of associations were observed between PhA and selected variables. Teixeira et al [42] reported that both whole-body and limb PhA were inversely associated with BMI in both genders, with body weight and FM in males, and with percentage body fat in females. On the other hand, whole-body and upper-limb PhA were positively associated with skeletal muscle mass and BCM.…”

“…As for the twenty-one single-center studies selected, sample size was below 200 subjects in fourteen [27e40], between 200 and 500 in two [41,42] and above 500 subjects in five [18,43e46]; . BIA measurement procedures were described in detail in 11 out of 21 papers [18,27,28,31,32,34,40,41,44e46].…”

“…Seven papers assessed changes of PhA values following bariatric surgery by comparing values before and from 6 weeks to 2 years after intervention [32e38,42]. Four studies have evaluated patients treated with Laparoscopic Sleeve Gastrectomy (LSG) or Roux-en-Y Gastric Bypass (RYGB) [34,35,37,38], two studies RYGB only [36,42], one LSG [33] and one laparoscopic gastric banding (LGB) [32]. Sample size ranged from 20 to 379 patients (age 18e83 yrs, mean BMI 35e54 kg/m 2 ).…”

“…Concerning the association with body composition changes, Teixeira et al [42] reported that the decline of PhA after RYGB was negatively associated with weight loss and positively with the decrease of BMI, skeletal muscle mass, FM, and visceral fat area. In the study by Vassilev et al [34], preoperative PhA positively correlated with the loss of excess weight and negatively with percentage body fat 12 months after LSG or RYGB.…”