Authors' response to van der Maas et al
We would like to thank van der Maas and colleagues for their interest in and useful feedback on our review . They raise several important points. First, regarding the interpretation of the studies included in the review, we focused on studies examining discontinuation of biologic disease modifying antirheumatic drugs (DMARDs) that examined patient outcomes. Thus, we had difficulty in fitting a tapering and discontinuation study  in the framework of our review since some patients fail during the tapering phase and never fully discontinue drug.
Nevertheless, we extracted outcome (maintenance of discontinuation) information from Figure 2D of their paper . We interpreted this figure as the "proportion free of failure" after discontinuation among those who underwent discontinuation (n = 12). Thus, it was interpreted as all patients failed by 7 months (around 200 days) after discontinuation. The "follow up duration" we defined in our review is the time since biologic discontinuation to failure (i.e., resumption of biologic DMARDs or disease flare) or study end. Thus, the follow-up duration we reported may have differed from the original study report because of the different framework of our review.
Second, the letter inquires about the thresholds for biologic discontinuation failure. Most studies focused on an absolute threshold either at remission (DAS28-ESR 2.6) or low disease activity (DAS28-ESR 3.2). Thus, we felt the relative threshold corresponding to this range of disease activity (i.e., change in DAS28-ESR > 0.6) was more relevant to our review. However, we agree that full description of the criteria is important.
Finally, we appreciate the suggestion of another study that could be included in this review. In a rapidly evolving scientific area with no standardized search terms, compiling a complete list of studies is challenging.
1. Yoshida K, Sung Y-K, Kavanaugh A, et al. Biologic discontinuation studies: a systematic review of methods. Ann Rheum Dis 2013 May 30.
2. Van der Maas A, Kievit W, van den Bemt BJF, et al. Down-titration and discontinuation of infliximab in rheumatoid arthritis patients with stable low disease activity and stable treatment: an observational cohort study. Ann Rheum Dis 2012 ;71(11):1849-54.
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