Table 2.

Regression coefficients and odds ratios with 95% confidence intervals as derived from the original model and the internally validated model

	Original model			Model after internal validation
Variable	Regression coefficient	Odds ratio (95% CI)	p-value	Regression coefficient*	Odds ratio (95% CI)
Intercept	-0.32	-	-	-0.23	-
Elevated sIL-2R levels	1.98	7.27 (1.86 – 28.40)	0.004	1.85	6.33 (1.73-28.17)
Total HRCT score	0.24	1.27 (1.06 - 1.52)	0.011	0.22	1.25 (1.04-1.50)
To calculate the absolute risk of a positive PET result: P(PET-positive) = (1 / (1 + exp(-(-0.23 + 1.85 * sIL-2R + 0.22 * HRCT score)))) * 100%

CI: confidence interval; sIL-2R: soluble interleukin-2 Receptor; HRCT: high-resolution computed tomography; PET: positron emission tomography.

^* Regression coefficients after adjustment for overfitting by shrinkage (shrinkage factor = 0.93); the intercept was re-estimated.