Table 1 Results from the methodological evaluation of the articles in this review
Criterion | Number | Percent |
|---|---|---|
Events per variable/overfitting (n = 40) | ||
Fulfilled | 39 | 97.5 % |
Not fulfilled | 1 | 2.5 % |
Conformity with a linear gradient (n = 19) | ||
Fulfilled | 0 | 0 % |
Not fulfilled | 19 | 100 % |
No continuous variable in multivariate analysis | 22 | |
Interactions between independent variables (n = 41) | ||
Interaction terms used | 14 | 34 % |
Coefficients tested | 14 | |
Coefficients not tested | 0 | |
Stratified results presented | 27 | 66 % |
Test for interactions | 3 | |
No test for interactions | 24 | |
Neither stratified results nor interaction terms discussed | 7 | 17 % |
Collinearity of independent variables (n = 39) | ||
Discussed | 1 | 2.6 % |
Not discussed | 38 | 97.4 % |
Validation of the statistical model (n = 41) | ||
Fulfilled | 0 | 0 % |
Sensitivity analysis/robustness checks | 3 | 7.3 % |
Not used | 38 | 92.7 % |
Statistical significance/confidence intervals (n = 41) | ||
Statistical significance for statistical model | 2 | 5.1 % |
No statistical significance for statistical model | 39 | 94.9 % |
P-value only presented as above/below the significance level | 14 | 34 % |
Confidence interval presented for exposure | 24 | 58 % |
Coefficients presented in statistical models with relative difference (n = 23) | ||
All coefficients presented for the statistical model | 13 | 52 % |
Not all coefficients presented for the statistical model | 12 | 48 % |
Goodness of fit test (n = 41) | ||
Fulfilled | 9 | 22 % |
Not fulfilled | 32 | 78 % |
Selection of variables (n = 41) | ||
Selection of candidate variables discussed | 13 | 32 % |
Selection of candidate variables not discussed | 28 | 68 % |
Selection of final variables in statistical model discussed | 5 | 12 % |
Selection of final variables in statistical model not discussed | 36 | 88 % |
Coding of variables (n = 41) | ||
No faults | 27 | 66 % |
Small faults | 11 | 27 % |
Major faults | 3 | 7.3 % |
Fitting procedure (n = 41) | ||
Performed | 3 | 7.3 % |
Not performed | 38 | 92.7 % |
Discussion of methodological concerns (n = 41) | ||
Yes | 31 | 76 % |
Limitations with statistical model | 6 | 15 % |
No | 10 | 24 % |