Statistical Methods
diabetes mellitus, DM2, dyslipidemia
REGRESSION, DIABETES MELLITUS, DYSLIPIDEMIA
Descriptive statistics were used to summarize patient characteristics. First, we calculated the change in blood values (Δ) between 6 months postoperative and preoperative blood values, i.e., the change after bariatric surgery. To investigate the clinical effect of UDCA, we used the unpaired t-test in the main analysis to compare the change in blood values between the group with UDCA treatment and the group with placebo treatment. In order to investigate the actual biochemical effect of UDCA which is not influenced by poor adherence, the second analysis comparing changes in blood values was performed in adherent patients only.In addition, sensitivity analyses were performed. The first sensitivity analysis was a cross-sectional comparison of blood values at 6 months after bariatric surgery in order to exclude preoperative factors that could influence the outcomes of UDCA treatment. This analysis was repeated in adherent patients only. The second sensitivity analysis was performed in patients without diabetes mellitus to explore the effect of DM2, which was present more often in the placebo group at baseline.We repeated the analyses in a subgroup with preoperatively elevated liver enzymes and in a subgroup with preoperative dyslipidemia to examine the influences of UDCA use in these specific subgroups. Patients were included in the first subgroup if any of the liver enzymes were elevated (total bilirubin, ALP, GGT, AST, or ALAT). Patients in the second subgroup were included if diagnosed with dyslipidemia but not requiring lipid-lowering drugs before and after bariatric surgery. All additional analyses were also performed using the unpaired t-test.Finally, regression analysis was used to evaluate whether increased ALP levels were associated with ASAT, ALAT, bilirubin, GGT, calcium, vitamin D, or PTH levels. IBM SPSS statistics (version 26, Armonk, New York) was used and two-sided 