Table 4 Selection of variables in multivariable analysis
From: Reporting methods in studies developing prognostic models in cancer: a review
| Â | % (n = 43*) |
|---|---|
Selection of variables for inclusion in multivariable analysis | Â |
   All candidate variables used (no selection) | 26 (11) |
   All candidate variables apart from a few with contra indications** | 5 (2) |
   Without statistical analysis |  |
Previous literature | 5 (2) |
Previous literature and few variables by investigator choice | 5 (2) |
   By statistical analysis |  |
Screening by univariable analysis - only significant variables | 37 (16) |
Screening by univariable analysis - significant variables and investigator choice | 11 (5) |
   Unclear/Not reported | 11 (5) |
Statistical modelling methods used within multivariable analysis | Â |
   A priori variables fixed, others added | 2 (1) |
   Backward elimination | 14 (6) |
   Forward selection | 5 (2) |
   Other (pairwise multiple testing for categories of variables) | 2 (1) |
   Unclear/Not reported | 77 (33) |
Methods for inclusion of variables in final model and prognostic index | Â |
   No selection. All variables kept in model | 14 (6) |
   Retain only significant variables based on P-value | 65 (28) |
   Retain significant variables plus variables based on previous literature | 2 (1) |
   Retain all variables but alter prognostic score after model to include only significant variables and adjust for other variables | 5 (2) |
   Retain only significant variables but alter prognostic score after final model | 5 (2) |
   Retain based on model goodness of fit | 2 (1) |
   Unclear/Not reported | 7 (3) |