Table 4 Multivariate linear regression analysis and general estimation equation for predicting BMI percent change from baseline at 6 months, one year and two years adjusted for type of surgery, age, sex, and preoperative body mass index before and after PSM

At 6 months: †

Primary RYGB

5.048

[2.470 to7.626]

< 0.001*

6.095

[3.469 to 8.721]

< 0.001*

Female

− 0.580

[-2.998 to1.839]

0.638

-1.373

[-4.870 to 2.123]

0.441

Age in years

− 0.091

[-0.190 to.007]

0.070

− 0.232

[-0.356 to − 0.109]

< 0.001*

Preoperative BMI ≥ 40

-16.101

[-18.89 to -13.305]

< 0.001*

-13.808

[-16.898 to -10.718]

< 0.001*

At 1 year: †

Primary RYGB

-6.849

[-9.027 to-4.672]

< 0.001*

-5.890

[-8.165 to -3.614]

< 0.001*

Female

− 0.391

[-2.434 to1.652]

0.707

− 0.443

[-3.473 to 2.588]

0.774

Age in years

0.007

[-0.077 to 0.090]

0.876

− 0.069

[-0.176 to 0.038]

0.207

Preoperative BMI ≥ 40

-13.888

[-16.24 to -11.526]

< 0.001*

-12.284

[-14.962 to -9.606]

< 0.001*

At 2 years: †

Primary RYGB

-9.948

[-11.531 to-8.366]

< 0.001*

-8.626

[-10.252 to -6.999]

< 0.001*

Female

− 0.187

[-1.672 to1.297]

0.804

− 0.554

[-2.719 to 1.611]

0.615

Age in years

0.005

[-0.055 to.066]

0.859

− 0.082

[-0.159 to -0.005]

0.036*

Preoperative BMI ≥ 40

-14.465

[-16.18 to-12.749]

< 0.001*

-13.140

[-15.053 to -11.227]

< 0.001*

General estimation equation regression analysis: ††

Est. Average

[95% CI]

Sig.

Est. Average

[95% CI]

Sig.

Type of surgery:

Conversional RYGB after LSG

-27.974

[-29.402 to -26.545}

< 0.001*

-27.701

[-29.372to -26.030]

< 0.001*

Primary RYGB

-31.891

[-32.990 to -30.792]

-30.487

[-32.158 to-28.816]

Preoperative BMI:

< 40

-22.523

[-24.216 to -20.831]

0.001*

-22.532

[-24.654 to -20.412]

0.001*

≥ 40

-37.341

[-38.273 to -36.409]

-35.655

[-37.039 to-34.270]