Variables independently correlated with increased reported operative difficulty score, multivariate analysis
| Variable | Estimated coefficient | Std. error of coefficient | P values |
| Total posterior measurement | −0.231 | 0.082 | 0.0063 |
| BMI | 0.083 | 0.021 | 0.00019 |
| Visceral obesity measurement | 0.142 | 0.037 | 0.0023 |
BMI, body mass index.