Univariate Cox regression analysis exploring factors associated with lung cancer diagnosis in idiopathic pulmonary fibrosis patients
| Parameter | HR (95% CI) | p-value |
| Age years | ||
| <60 | Ref. | |
| ≥60 | 1.402 (0.714–2.755) | 0.326 |
| Sex | ||
| Female | Ref. | |
| Male | 4.809 (1.752–13.199) | 0.002 |
| BMI kg·m−2 | ||
| ≥25 | Ref. | |
| ≥18.5–<25 | 1.258 (0.732–2.162) | 0.407 |
| <18.5 | 0.942 (0.218–4.083) | 0.937 |
| Unknown | 1.854 (0.246–13.954) | 0.549 |
| Smoking history | ||
| None | Ref. | |
| Smoker | >999.999 (0.000–−) | 0.985 |
| Smoking exposure pack-years | ||
| <35 | Ref. | |
| ≥35 | 3.053 (1.747–5.334) | <0.001 |
| Emphysema | ||
| None | Ref. | |
| Present | 2.944 (1.823–4.753) | <0.001 |
| FVC % pred | ||
| ≥80 | Ref. | |
| <80 | 0.449 (0.212–0.952) | 0.037 |
| Unknown | 1.639 (0.991–2.710) | 0.054 |
| FEV1/FVC % | ||
| ≥70 | Ref. | |
| <70 | 1.877 (0.963–3.656) | 0.064 |
| Unknown | 2.330 (1.382–3.926) | 0.001 |
| DLCO % pred | ||
| ≥80 | Ref. | |
| <80 | 2.179 (0.990–4.800) | 0.053 |
| Unknown | 2.574 (1.250–5.305) | 0.010 |
| PaO2 mmHg | ||
| ≥70 | Ref. | |
| <70 | 1.421 (0.628–3.216) | 0.399 |
| Unknown | 0.850 (0.504–1.433) | 0.542 |
| ESR mm·h−1 | ||
| <35 | Ref. | |
| ≥35 | 1.673 (0.946–2.959) | 0.077 |
| Unknown | 1.391 (0.774–2.501) | 0.27 |
| CRP mg·dL−1 | ||
| <0.3 | Ref. | |
| ≥0.3 | 1.217 (0.742–1.994) | 0.437 |
| Unknown | 0.983 (0.427–2.266) | 0.968 |
| Albumin g·dL−1 | ||
| ≥3.5 | Ref. | |
| <3.5 | 2.047 (0.910–4.601) | 0.083 |
| Unknown | 0.864 (0.521–1.432) | 0.571 |
| KL-6 U·mL−1 | ||
| <500 | Ref. | |
| ≥500 | 1.092 (0.493–2.420) | 0.829 |
| Unknown | 2.041 (0.985–4.227) | 0.055 |
HR: hazard ratio; BMI: body mass index; FVC: forced vital capacity; FEV1: forced expiratory volume in 1 s; DLCO: diffusing capacity of the lung for carbon monoxide; PaO2: arterial oxygen tension; ESR: erythrocyte sedimentation rate; CRP: C-reactive protein; KL: Krebs von der Lungen.