Cox proportional hazards analysis of survival in 584 patients with cystic fibrosis: multivariate analysis
| Parameter | χ2value | p value | RR (95 % CI) |
| % ideal weight | 5.9 | 0.015 | 0.984 (0.971 to 0.997) |
| % predicted FEV1 | 63.4 | <0.0001 | 0.951 (0.940 to 0.963) |
| % ideal weight | 56.5 | <0.0001 | 0.955 (0.944 to 0.967) |
| Age | 0.5 | 0.476 | 0.990 (0.963 to 1.018) |
| % ideal weight | 53.8 | <0.0001 | 0.956 (0.944 to 0.967) |
| Female sex | 0.3 | 0.611 | 1.091 (0.779 to 1.529) |
| % ideal weight | 8.4 | 0.004 | 0.968 (0.947 to 0.990) |
| % predicted FEV1 | 17.4 | <0.0001 | 0.953 (0.931 to 0.975) |
| Pao 2 | 1.7 | 0.187 | 0.892 (0.752 to 1.057) |
| Paco 2 | 5.1 | 0.024 | 0.714 (0.533 to 0.957) |
| Age | 1.0 | 0.328 | 0.982 (0.946 to 1.019) |
| Female sex | 0.05 | 0.819 | 0.945 (0.581 to 1.537) |
FEV1 = forced expiratory volume in one second; Pao 2 = arterial oxygen tension; Paco 2 = arterial carbon dioxide tension; % ideal weight = weight as percentage of the predicted ideal weight.