Maxime Verhoeven

143 Cost-effectiveness of treat-to-target strategies over 5 years with a combination of a substantial TCZ price reduction, and treatment of only the subgroup of early RA patients with a DAS28>5.1 at start of treatment, TCZ-based strategies may become cost-effective. Results of these analyses were based on the human capital approach, as it is internationally the most widely used method, and accounts most extensively for productivity effects in our sensitivity/scenario analyses, where the aim was to investigate if TCZ-based strategies could be cost-effective in some of the sensitivity/scenario analyses. No sensitivity/scenario analyses were performed for the type or costs of follow-up treatment in patients who dropped out because the number of patients dropping out as well as the duration of this follow-up treatment were similar between treatment strategy arms, indicating that these analyses would not have resulted in differences in costs regarding the comparison of the treatment strategies. Overall no differences in QALYs were shown in our study, which is in line with the majority of earlier performed studies as shown in a systematic review. 7 The, unexpected, numerically lower number of QALYs obtained with TCZ versus MTX over 5 years, may be due to the fact that TCZ was not self-administered. The (additional) hospital visits for TCZ infusions may have been a burden for patients, resulting in QALY losses. We would expect a gain in QALY for early RA patients if treated with TCZ subcutaneously, compared to intravenously. 16 The current study has several limitations. Firstly, there was considerable missing data, which we handled by resampling using a large number of bootstraps (i.e., 10,000) and imputation. This two-step method was previously described as an optimal way to handle uncertainty due to both sampling and missing of data. 14 Secondly, our study had a reasonable short 5-year time horizon, whereas a life-long time horizon would be ideal to establish the final effect of short term intervention in early RA, given that it is a chronic disease. Although extension of the time horizon to life-time would have been possible with a health economic modeling approach (e.g., discrete event simulation, Markov modeling) using our patient data as part of the input, this was beyond the main aim of this paper, but would be interesting for future research. Thirdly, it was not possible to calculate the exact NSAID costs. We assume that our choice for naproxen, as one of the three most used NSAIDs in the Netherlands, with limited price differences, results in a plausible estimate of NSAID costs for this population in the Netherlands. Furthermore, the combination of NSAID and other csDMARD costs (i.e., other medication costs) are only maximally 1% of total medication costs. Therefore, it is unlikely that a more precise estimate of NSAID costs would influence our results. Strengths of the current study are the availability of ‘real-life’ data on quality of life and resource use, preventing the need for models to estimate outcomes. Besides, the 317 patients included in the current analysis were treated according to the treat-to- target approach, which enhance the generalizability for RA patients in the Netherlands and other European countries. 7