OBJECTIVES: The development of antidrug antibody (ADAb) causes the failure of initial tumor necrosis factor-alpha blocker (TNF-α blocker) in rheumatoid arthritis (RA) patients. Patients who develop ADAb against 1^st TNF-blocker have a high likelihood of failing to 2^nd TNF-blocker. ADAb-screening is commonly used as a supportive tool for switching to 2^ndTNF-α blocker or non-TNF biologics in Europe but not standard of care in the United States. Moreover, no evidence of value of ADAb-screening in RA patients exists. This study estimated incremental effectiveness and cost of ADAb-screening as compared to no screening.  METHODS: A literature-informed decision tree model with 1-year time horizon was used for moderate-to-severe RA patients who failed 1^stTNF-α blocker from a United States payer perspective. The model consisted of two alternatives as ADAb screening or non-screening. In ADAb screening arm, there was test positive or test negative branches. Each screening result included the probability of receiving a 2nd TNF-α blocker or non-TNF biologic. Each treatment resulted in a likelihood of response or failure. Response was defined as an improvement of 28-joint count Disease Activity Score >1.2 units. The pathway of non-screening was similar to ADAb-screening, but with screening naïve probabilities of treatment and response/failure.  RESULTS: Over 1 year treatment period, ADAb-screening was more costly but more effective than no screening. Patients who received ADAb-screening had 82.0% chance of treatment response with an average of $28,218, while patients who did not get screened had 78.5% chance of treatment response with an average of $28,053. The incremental response was 3.5% with additional cost as $164. The incremental cost-effectiveness ratio was $4,641 per additional responder. CONCLUSIONS: ADAb-screening increases the likelihood of response in moderate-to-severe RA patients and slightly increases overall cost of RA treatment. Uncertainty in this analysis could be reduced with prospective or observational analyses.