Maxime Verhoeven

137 Cost-effectiveness of treat-to-target strategies over 5 years being significant. Regarding the 2 to 5-year evaluation period the difference in total cost increases and the QALY difference remains the same, decreasing the cost effectiveness of TCZ+MTX compared to MTX. For TCZ, direct healthcare costs (RA medication costs excluded), and productivity loss costs are lower compared to MTX (not significant), but total cost are significantly higher. Over a 5-year evaluation period the difference in total cost remains constant and significantly higher, except if productivity loss costs are calculated using the human capital approach, which results in a smaller not significant increase in costs compared to those of MTX. Differences in QALYs are not significant, but the small numerical advantage over the 2-year period is lost over the 5-year period, leading to a small disadvantage in QALYs for TCZ vs. MTX. TCZ+MTX has an ICER between 526,674 and 594,021 per QALY gained compared to MTX (depending on perspective taken and method of calculating productivity loss costs) and is inferior in 23% of all bootstrap samples over 5 years. TCZ has a negative ICER (between -426,967 and -149,241 depending on the perspective taken and method of calculating productivity loss costs) as on average QALYs were lost over 5 years, and TCZ is inferior in between 47% and 65% of all bootstrap samples over 5 years. Taken the societal perspective, using human capital approach, TCZ dominated (i.e., more QALYs and less costs) in 8% of all bootstrap samples, and in 18% TCZ was found less expensive, but also less effective, Figure 2. Outcomes based on undiscounted values are shown in Supplementary Table 5. The probability of TCZ(+MTX) being a cost-effective intervention over 5 years, using different WTP thresholds for a QALY, was in general low, but somewhat higher for TCZ compared to TCZ+MTX, see Figure 3 and Supplementary Figure 1-2. Table 2 Mean (2.5-97.5 percentile) difference in costs (€, rounded to the nearest hundreds) and QALYs, and ICER with distribution in cost effectiveness plane (%). TCZ+MTX vs. MTX TCZ vs. MTX Over 2 years Medication costs 14,800 (12,000 to 17,600) 15,900 (13,100 to 18,600) Direct healthcare costs 8,700 (4,100 to 13,400) -1,400 (-4,700 to 1,800) Indirect non healthcare costs -600 (-1,200 to 0) 200 (-700 to 1,100) Productivity loss costs # 2,500 (-4,200 to 9,300) -3,200 (-9,900 to 3,400) Productivity loss costs $ 400 (-1,100 to 1,900) -300 (-1,900 to 1,200)   Total cost and effect Healthcare perspective 23,500 (18,000 to 29,000) 14,500 (10,000 to 18,900) Societal perspective # 25,300 (17,200 to 33,300) 11,400 (3,600 to 19,300) Societal perspective $ 23,200 (17,800 to 28,600) 14,400 (9,600 to 19,000) QALYs 0.06 (-0.02 to 0.13) 0.03 (-0.05 to 0.11) 7