TABLE 2.
Multivariable logistic regression results for operative mortality modeled as a function of Society of Thoracic Surgeons predicted risk of mortality (STS PROM) (with restricted cubic splines), surgeon operative volume (with restricted cubic splines), and operative year.* Ranked by covariate likelihood ratio (Wald χ2 test statistic)
| Covariate | Likelihood ratio (Wald χ2) | Odds ratio (95% confidence interval) | P value |
|---|---|---|---|
| STS PROM (linear) | 846.7 | 1.89 (1.68–2.09) | <.0001 |
| STS PROM (nonlinear) | 251.5 | 6.59 (5.35–8.12) | <.0001 |
| Operative year (reference = 2005) | 46.3 | <.0001 | |
| 2001 | 0.38 (0.15–0.96) | ||
| 2002 | 0.92 (0.55–1.53) | ||
| 2003 | 1.15 (0.72–1.83) | ||
| 2004 | 0.72 (0.49–1.07) | ||
| 2006 | 0.92 (0.67–1.28) | ||
| 2007 | 0.90 (0.65–1.24) | ||
| 2008 | 1.43 (1.04–1.97) | ||
| 2009 | 1.79 (1.32–2.43) | ||
| 2010 | 1.46 (1.06–2.01) | ||
| 2011 | 1.27 (0.90–1.78) | ||
| 2012 | 1.34 (0.75–2.39) | ||
| Surgeon operative volume (linear) | 16.3 | 0.31 (0.47–0.15) | .0003 |
| Surgeon operative volume (nonlinear) | 0.8 | 0.73 (0.62–0.86) | .36 |
STS PROM, Society of Thoracic Surgeons predicted risk of mortality.
*
Model performance characteristics: C statistic = 0.81, Nagelkerke Pseduo R2 = 0.16.