Rheumatoid arthritis is a chronic autoimmune disease that primarily causes inflammation, pain and stiffness in the joints. People with severe disease may be treated with biological disease-modifying anti-rheumatic drugs, including tumour necrosis factor-α inhibitors, but the efficacy of these drugs is hampered by the presence of anti-drug antibodies. Monitoring the response to these treatments typically involves clinical assessment using response criteria, such as Disease Activity Score in 28 joints or European League Against Rheumatism. Enzyme-linked immunosorbent assays can also be used to measure drug and antibody levels in the blood. These tests may inform whether or not adjustments to treatment are required or help clinicians to understand the reasons for treatment non-response or a loss of response.
Systematic reviews were conducted to identify studies reporting on the clinical effectiveness and cost-effectiveness of using enzyme-linked immunosorbent assays to measure drug and anti-drug antibody levels to monitor the response to tumour necrosis factor-α inhibitors [adalimumab (Humira
Two studies were identified: (1) a non-randomised controlled trial, INGEBIO, that compared standard care with therapeutic drug monitoring using Promonitor
There is limited relevant research evidence and much uncertainty about the clinical effectiveness and cost-effectiveness of using enzyme-linked immunosorbent assay-based testing for therapeutic drug monitoring in rheumatoid arthritis patients. INGEBIO had serious limitations in relation to the National Institute for Health and Care Excellence scope: only one-third of participants had rheumatoid arthritis, the analyses were mostly not by intention to treat and the follow-up was 18 months only. Moreover, the outcomes might not be generalisable to the NHS.
Based on the available evidence, no firm conclusions could be made about the cost-effectiveness of therapeutic drug monitoring in England and Wales.
Further controlled trials are required to assess the impact of using enzyme-linked immunosorbent assays for monitoring the anti-tumour necrosis factors in people with rheumatoid arthritis.
This study is registered as PROSPERO CRD42018105195.
This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in 
Rheumatoid arthritis is a long-term condition that causes pain, swelling and stiffness in the joints. People with severe disease may be treated with drugs called tumour necrosis factor-α inhibitors [adalimumab (Humira