Maxime Verhoeven

96 Chapter 5 Supplementary Table S3 average absolute chance (proportion) of early RA patients with no radiographic progression at baseline per treatment arm, and absolute risk difference between treatment arms. Modifier Group Comparison Relative chance Absolute risk in TCZ+MTX arm (%) Absolute risk in TCZ- monotherapy arm (%) Absolute risk difference (%) Total SvdH scores Baseline joint damage Low tcz vs tcz+mtx 0.91 91 83 8 High tcz vs tcz+mtx 1.02 71 72 1 Baseline DAS28 Low tcz vs tcz+mtx 1.04 82 85 3 High tcz vs tcz+mtx 0.92 83 76 7 Erosion scores Baseline joint damage Low tcz vs tcz+mtx 0.95 93 88 5 High tcz vs tcz+mtx 1.03 77 79 2 Baseline DAS28 Low tcz vs tcz+mtx 1.02 87 89 2 High tcz vs tcz+mtx 0.97 85 82 3 Joint space narrowing scores Baseline joint damage Low tcz vs tcz+mtx 0.97 98 95 3 High tcz vs tcz+mtx 0.91 87 79 8 Baseline DAS28 Low tcz vs tcz+mtx 0.98 93 91 2 High tcz vs tcz+mtx 0.96 93 89 4 Number of patients in low level baseline joint damage subgroup; 160 in TCZ vs. 166 in TCZ+MTX, number of patients in high level baseline joint damage subgroup; 129 in TCZ vs. 132 in TCZ+MTX. Number of patients in low level baseline DAS28 subgroup; 149 in TCZ vs. 145 in TCZ+MTX, number of patients in high level baseline DAS28 subgroup; 146 in TCZ vs. 153 in TCZ+MTX. Low= low level subgroup; High= high level subgroup; DAS28= disease activity score assessing 28 joints; TCZ= tocilizumab, MTX= methotrexate. Interpretation: The relative chance of not having radiographic progression of 0.91 for TCZ vs. TCZ+MTX for patients with low baseline joint damage (TCZ vs TCZ+MTX Low) can be translated to an absolute risk difference using the average percentage of patients treated with TCZ+MTX who have no-progression in this group (reference group) of 91%. Using the RR and reference rate of no-progression would be 0.91*91% = 83% for patients treated with TCZ, and the absolute risk difference thus 8%. For patients with high baseline damage, the reference rate of no-progression is 71%, rate of no-progression with TCZ of 1.02*71% = 72%, and an absolute difference of 1%.