Table 2. Univariate and multivariate Cox regression analyses to identify clinical predictors of grade ≥ 2 and 3 radiation pneumonitis.
| Characteristic | grade ≥ 2 radiation pneumonitis | grade ≥3 radiation pneumonitis | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Univariate Analysis | Multivariate Analysis* | Univariate Analysis | Multivariate Analysis* | |||||||||
| HR | 95% CI | P | HR | 96% CI | P | HR | 95% CI | P | HR | 96% CI | P | |
| Age (≥ 66 vs. < 66) | 1.236 | 0.964–1.585 | 0.095 | 1.347 | 1.042–1.741 | 0.023 | 1.545 | 0.993–2.401 | 0.054 | 1.825 | 1.158–2.875 | 0.01 |
| Sex (male vs. female) | 1.005 | 0.784–1.290 | 0.966 | NI | 1.188 | 0.764–1.848 | 0.443 | NI | ||||
| Race (black and other vs. white) | 1.053 | 0.742–1.493 | 0.773 | NI | 1.048 | 0.568–1.934 | 0.881 | NI | ||||
| Disease stage (IIIB, IV, recurrence vs. I–IIIA) |
1.010 | 0.782–1.303 | 0.941 | NI | 0.779 | 0.499–1.217 | 0.273 | NI | ||||
| Histology | ||||||||||||
| SCC & Other vs. Adenocarcinoma | 0.954 | 0.743–1.224 | 0.711 | NI | 0.968 | 0.625–1.498 | 0.883 | NI | ||||
| KPS (≥ 80 vs. < 80) | 0.771 | 0.554–1.075 | 0.125 | 0.820 | 0.584–1.153 | 0.254 | 0.510 | 0.305–0.852 | 0.01 | 0.552 | 0.325–0.936 | 0.027 |
| Induction chemotherapy (yes vs. no) | 1.026 | 0.794–1.327 | 0.843 | NI | 1.246 | 0.802–1.938 | 0.328 | NI | ||||
| Smoking status (current/former vs. never) |
0.825 | 0.532–1.279 | 0.390 | NI | 1.123 | 0.489–2.580 | 0.784 | NI | ||||
| Total dose (≥ 69.03 vs. < 69.03) |
0.799 | 0.622–1.026 | 0.079 | NI | 0.657 | 0.421–1.026 | 0.065 | NI | ||||
| Gross tumor volume (≥ 95.2 cm3 vs. < 95.2 cm3) |
1.539 | 1.186–1.999 | 0.001 | NI | 2.76 | 1.678–4.539 | < 0.001 | NI | ||||
| Mean lung dose (≥ 17.9 Gy vs. < 17.9 Gy) | 2.080 | 1.601–2.703 | < 0.001 | 2.191 | 1.680–2.856 | < 0.001 | 3.922 | 2.318–6.639 | < 0.001 | 4.253 | 2.493–7.257 | < 0.001 |
| Radiation modality (proton vs. 3D–CRT + IMRT) |
0.932 | 0.688–1.263 | 0.650 | NI | 0.65 | 0.359–1.176 | 0.154 | 0.766 | 0.419–1.4 | 0.386 | ||
*Characteristics with a P value of <0.05 in the univariate analysis were entered into the multivariate model in a stepwise fashion and were removed if at any point the P value was > 0.20.
Abbreviations: HR, hazard ratio; CI, confidence interval; NI, not included; KPS, Karnofsky Performance Status score; SCC, squamous cell carcinoma; 3D–CRT, 3–dimensional conformal (photon) radiation therapy; IMRT, intensity–modulated (photon) radiation therapy