Background/Purpose: Studies on patients with severe rheumatoid arthritis (RA) are widely reported. However, limited data are available on patients with moderate disease activity (MOD). Recent evidence, including data from the PRESERVE trial, have highlighted the disease burden in MOD patients, and further warrant an understanding of disease progression/remission and impact of treatment strategies in this patient population from longitudinal clinical registries.

Methods: Patients enrolled in CORRONA (a large US multicenter, longitudinal database of RA patients) from March 2002 through April 2012, aged ≥18 years, who moved from LDA (CDAI≤10) to MOD (10<10CDAI<22) were included at baseline. Patients were followed over time to estimate the proportion with Low CDAI / Moderate CDAI/ Severe CDAI at the 6 month and 12 month follow up visit. Additionally proportion of patients accelerating between baseline and 6 month; and 6 month and 12 month follow up visit were reported. Accelerations were defined as (i) add/switch a DMARD (ii) increase dose only (iii) both add/switch DMARD and increase dose.  Patients were excluded if (i) time between last LDA and first Moderate CDAI was > 1 year (ii) they moved from LDA to Severe CDAI before Moderate CDAI. We included patients with CDAI at all three visits (first moderate, 6 month follow up, and 12 month follow up).

Results: 4,118 RA patients met the inclusion criteria. At 6 months, the majority (2,451/4,118; ~60%) were LDA, while 32% (1,298/4,118) remained MOD, and 9% progressed to severe (CDAI>22). Of those who were at LDA at 6 months (N=2,451), 76% remained at LDA at 12 months; while 46% of those who were MOD at 6 months actually improved to LDA at 12-months. Majority (69%) of those severe at 6-months had either improved to LDA or MOD at 12-months. Between baseline and 6-month visit, 39% (1,590/4,118) accelerated by adding/switching a DMARD (43%), increasing the dose (43%), or both (12%) and in spite of that, 10% patients had progressed to severe (160/1,590) at the 6-month visit. Eight percent of  patients with no accelerations from baseline (2,528) worsened (209/2,528) at the 6-month visit. Between 6 and 12 month visit, patients initially accelerated but with LDA or MOD at 6-month did not receive high number of accelerations. Nearly half of those severe at 6-months were accelerated, although a quarter (25%) continued to demonstrate severe disease activity at the 12-month visit.

Conclusion: Patients identified with moderate disease activity (10