Impact of alternative variable choices for TNFi use on spinal radiographic progression from different multivariable models*
| Model | Alternative variable choices for TNFi use | OR | 95% CI | p Value |
| 1 | TNFi use prior to radiographic interval (yes versus no) | 0.50 | 0.28 to 0.88 | 0.02 |
| 2 | Number of years of continuous use of TNFi prior to interval† | 0.79 | 0.66 to 0.94 | 0.01 |
| 3 | ≤4 years of TNFi use prior to radiographic interval | 0.55 | 0.31 to 0.98 | 0.04 |
| >4 years of TNFi use prior to radiographic interval | 0.30 | 0.10 to 0.90 | 0.03 | |
| 4 | TNFi use prior to radiographic interval (yes versus no) | 0.52 | 0.27 to 0.98 | 0.05 |
| TNFi use during the radiographic interval (yes versus no) | 0.87 | 0.49 to 1.56 | 0.64 | |
| 5 | TNFi use prior to radiographic interval (yes versus no) | 0.54 | 0.28 to 1.03 | 0.06 |
| TNFi use during ≤50% of duration of radiographic interval | 1.41 | 0.66 to 3.00 | 0.37 | |
| TNFi use during >50% of duration of radiographic interval | 0.81 | 0.43 to 1.50 | 0.50 |
*Summarised results from different multivariable models with same covariates used as in figure 1 with the exception of the TNFi variable(s). Full models are depicted in the online supplementary tables S3–S6. Model 1 corresponds to the model in figure 1A. Spinal progression was defined as ≥2 mSASSS units in a 2-year interval. Analyses performed in 616 radiographic intervals from 432 patients after multiple imputation of missing covariate data.
†Estimated effect of TNFi per year of continuous TNFi use.
TNFi, tumour necrosis factor inhibitor.