Variable, measures and methods of analysis
| Variable/outcome | Hypothesis | Outcome measure | Methods 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 remission | Logistic regression (primary analysis) and Cox proportional hazards model (exploratory analysis) |
| Secondary outcome | |||
| Glycaemic control | Reduction is higher in the RYGB+BMT arm compared with the BMT-only arm. | Fast glucose in mg/dL | Mixed-effects generalised linear models |
| HbA1c | Reduction is higher in the RYGB+BMT arm compared to the BMT-only arm. | HbA1c levels (in %) | Mixed-effects generalised linear models |
| Blood pressure control | The 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 Hg | Mixed-effects generalised linear models |
| Lipid control | The 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/dL | Logistic regression |
| Retinopathy | Resolution of retinopathy | Number of patients achieving resolution or reduction in the degree of retinopathy and/or macular oedema (severity scale) | Logistic regression |
| Neuropathy | New development or worsening of neuropathy | Number of patients with new or worsening of neuropathy | Logistic regression |
| Medical treatment | Reduction of medication for T2DM | Number of medications necessary for targeting euglycaemia | Linear regression |
| Hepatic fibrosis | Improvement of fibrosis | Reduction of hepatic elastographic resistance | Logistic regression |
| Voiding dysfunction | Improvement of voiding dysfunction | Reduction in the degree of voiding dysfunction symptoms | Logistic 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 questionnaire | Mixed-effects generalised linear models |
| Clinical and sociodemographic variables | |||
| Age | There is no difference between the RYGB+BMT arm compared with the BMT-only arm at baseline. | Years | Student’s t-test |
| BMI | kg/m2 | Student’s t-test | |
| Weight | kg | Student’s t-test | |
| Gender | 1=male, 0=female | Fisher's exact test | |
| Waist circumference | cm | Student’s t-test | |
| Urinary albumin | g/dL | Student’s t-test | |
| Creatinine | mg/dL | Student’s t-test | |
| Fasting blood glucose | mg/dL | Student’s t-test | |
| Total, HDL and LDL cholesterol | mg/dL | Student’s t-test | |
| Triglycerides | mg/dL | Student’s t-test | |
| Diastolic and systolic blood pressure | mm Hg | Student’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.