Table 3
Final result of multivariate analysis of parameters used to predict mortality as part of Cox proportional hazards method for all cause mortality (n = 170 total, deaths = 15) and respiratory mortality (n = 164, deaths = 9)
| B | p value | Hazard ratio | |
|---|---|---|---|
| Most significant parameter from univariate analysis entered at step 1, then parameters that remain significant entered in subsequent steps. All parameters included as in univariate analysis in table 2; only significant covariates shown at each step. B = estimated coefficient; significance shown (p value). Hazard ratio = eB, the predicted multiplicative change in the hazard for a unit increase in the predictor (>1 indicates that, as the predictor increases, the hazard, i.e. mortality, also increases); 95% confidence intervals shown in parentheses. In this model the hazard ratios for the significant covariates shown at each step are additive. | |||
| All cause mortality: | |||
| Step 1: Upper expiratory scan | 0.039 | 0.001 | 1.039 (1.015 to 1.064) |
| Step 2 (final): Upper expiratory scan | 0.037 | 0.003 | 1.038 (1.012 to 1.064) |
| Age | 0.059 | 0.035 | 1.061 (1.004 to 1.121) |
| Respiratory mortality: | |||
| Step 1: Upper expiratory scan | 0.053 | 0.001 | 1.054 (1.022 to 1.087) |
| Step 2: Upper expiratory scan | 0.054 | 0.001 | 1.056 (1.021 to 1.091) |
| Age | 0.102 | 0.015 | 1.100 (1.018 to 1.187) |
| Step 3: Upper expiratory scan | 0.031 | 0.161 | 1.031 (0.988 to 1.076) |
| Age | 0.102 | 0.016 | 1.108 (1.019 to 1.204) |
| Lower expiratory scan | 0.084 | 0.037 | 1.088 (1.005 to 1.177) |
| Step 4 (final): Lower expiratory scan | 0.099 | 0.006 | 1.105 (1.028 to 1.186) |
| Age | 0.097 | 0.020 | 1.102 (1.015 to 1.196) |
