Predictor

Coefficient

SE

Hazard ratio (95% CI)

pvalue


SUV_{95}^{a}

0.18

0.057

1.2 (1.11.3)

<0.002

Age^{b}

0.34

0.14

1.4 (1.11.8)

0.013

V_{30}

0.05

0.02

1.1 (1–1.1)

0.011

 ^{a}Scaled by 10.
 ^{b}Standardized age was used with origin corresponding to the mean of 64.
 Note: SE = standard error of the estimated coefficient parameter; CI = confidence interval for the hazard ratio; Stepwise backward model selection based on generalized Akaike information criterion was used; symptomatic radiation pneumonitis was conditionally independent of tumor location, stage, histology, smoking status, treatment type, and MLD in the presence of SUV_{95}, V_{30}, and age; pvalues derived from twosided hypothesis tests using Wald chisquare; the rate of symptom development was increased significantly with SUV_{95}, V_{30}, and age.