Table 3

Variable, measures and methods of analysis

Variable/outcomeHypothesisOutcome measureMethods of analysis
Primary outcome
 Remission (uACR<30 µg of albumin/mg of creatinine)The proportion of remission is higher at 12, 24 and 60 months in the RYGB+BMT arm compared with the BMT-only arm.Number of participants achieving remissionLogistic regression (primary analysis) and Cox proportional hazards model (exploratory analysis)
Secondary outcome
 Glycaemic controlReduction is higher in the RYGB+BMT arm compared with the BMT-only arm.Fast glucose in mg/dLMixed-effects generalised linear models
 HbA1cReduction is higher in the RYGB+BMT arm compared to the BMT-only arm.HbA1c levels (in %)Mixed-effects generalised linear models
 Blood pressure controlThe proportion of patients with blood pressure control is higher in the RYGB+BMT arm compared with the BMT-only arm.Number of participants achieving systolic blood pressure <130 mm Hg and diastolic <80 mm HgMixed-effects generalised linear models
 Lipid controlThe proportion of patients with lipid control is higher in the RYGB+BMT arm compared with the BMT-only arm.Number of participants with LDL<100 or <70 mg/dL in patients with previous cardiovascular events; HDL>50 mg/dL and triglycerides <150 mg/dLLogistic regression
 RetinopathyResolution of retinopathyNumber of patients achieving resolution or reduction in the degree of retinopathy and/or macular oedema (severity scale)Logistic regression
 NeuropathyNew development or worsening of neuropathyNumber of patients with new or worsening of neuropathyLogistic regression
 Medical treatmentReduction of medication for T2DMNumber of medications necessary for targeting euglycaemiaLinear regression
 Hepatic fibrosisImprovement of fibrosisReduction of hepatic elastographic resistanceLogistic regression
 Voiding dysfunctionImprovement of voiding dysfunctionReduction in the degree of voiding dysfunction symptomsLogistic regression
 Quality of life (SF-36)Quality of life is higher in the RYGB+BMT arm compared with the BMT-only arm.Quality of life questionnaireMixed-effects generalised linear models
Clinical and sociodemographic variables
 AgeThere is no difference between the RYGB+BMT arm compared with the BMT-only arm at baseline.YearsStudent’s t-test
 BMIkg/m2Student’s t-test
 WeightkgStudent’s t-test
 Gender1=male, 0=femaleFisher's exact test
 Waist circumferencecmStudent’s t-test
 Urinary albuming/dLStudent’s t-test
 Creatininemg/dLStudent’s t-test
 Fasting blood glucosemg/dLStudent’s t-test
 Total, HDL and LDL cholesterolmg/dLStudent’s t-test
 Triglyceridesmg/dLStudent’s t-test
 Diastolic and systolic blood pressuremm HgStudent’s t-test
  • BMT, best medical treatment; HbA1c, glycated haemoglobin; HDL, high-density lipoprotein; LDL, low-density lipoprotein; RYGB, Roux-en-Y gastric bypass; SF-36, 36-item Short Form Health Survey; T2DM, type 2 diabetes mellitus; uACR, urine albumin-to-creatinine ratio.