Background/Purpose: Adalimumab (ADA) was approved in the US in 2002 for rheumatoid arthritis (RA), and subsequently approved for the management of other inflammatory diseases such as Crohn’s disease, ulcerative colitis, plaque psoriasis, psoriatic arthritis, and ankylosing spondylitis. Expanded use of ADA has resulted in changes to manufacturing processes and production scale, making it important to examine the clinical response to ADA over time. This study aimed to assess the response rate to ADA in patients with RA over the years since its US approval.

Methods: Biologic-naïve patients with moderate to severe RA (Clinical Disease Activity Index [CDAI]>10) who initiated ADA during follow-up in the Corrona registry (2003–16) and had a 6-month registry visit (3–9 month window) were included in the study. Six groups were defined based on year of ADA initiation: 2003−05, 2006–07, 2008−09, 2010–11, 2012−13, and 2014−16. Patient characteristics at time of initiation were summarized by group year. Outcomes included percentage of patients with low disease activity (LDA)/remission (CDAI≤10) and modified American College of Rheumatology (mACR)20/50/70 (which do not include acute phase reactants) at 6-month follow-up. Non-response was imputed for patients switching to another biologic prior to 6 months. Chi-square tests were done to examine differences in response rates by group. Response rates were also compared among groups adjusting for covariates that differed at time of initiation using logistic regression models.

Results: Of 23,169 biologic-naïve patients, 1949 initiated ADA, 1056 had baseline CDAI>10, and 820 who had a 6‑month follow-up visit were included. In earlier year groups, patients were younger at time of disease onset (44.5 years in 2003−05, 47.1 years in 2006−07, 46.5 years in 2008−09, 51.6 years in 2010−11, 48.3 years in 2012−13 and 51.1 years in 2014−16; P=.0001), but had longer disease duration (10.8 years in 2003−05, 8.0 years in 2006−07, 5.9 years in 2008−09, 3.7 years in 2010−11, 4.8 years in 2012−13 and 4.6 years in 2014−16; P<.0001) compared with later year groups. At least 2/3 of patients remained on ADA at 6-month follow-up (range: 66% in 2014−16 to 77% in 2003−05). In each group, 43%−52% of patients achieved LDA/remission (Table). No significant differences in mACR20/50/70 rates were seen across groups.

Conclusion: No differences in clinical response rates (CDAI and modified ACR20/50/70) to ADA were noted over time among patients with RA in a real-world setting. The findings of this study indicate a consistent clinical response to ADA in RA patients since the market launch of the drug.