Background/Purpose:

Current clinical practice guidelines recommend remission, and if not possible, low disease activity (LDA) as the treatment target in rheumatoid arthritis (RA).  Patients should also be assessed frequently to facilitate achieving this target as early as possible. It has been previously shown that reaching LDA at 1 year is associated with better long-term functional and radiographic outcomes in an early RA cohort that enrolled patients prior to the introduction of T2Tconcept and the widespread use of biologics¹. Our objective was to assess the predictive validity of reaching LDA at an earlier time point (6 mo), the desired goal in current guidelines, on future disability.

Methods:

Data from Canadian early ArThritis Cohort (CATCH) including patients with early RA (symptom duration ≤ 12 mo) were used. Patients with at least two years of follow-up were included. The outcome was HAQ-DI at 2 years and the main predictor was LDA at 6 mo, measured by Clinical Disease Activity Index.  Linear regression analysis was used for assessment of the impact of LDA (y/n) on HAQ at 2 years adjusting for potential confounders including baseline LDA, HAQ, age, sex, ESR, RF, use of DMARDs, steroids and biologics. We included baseline and 6-mo LDA interaction in the model and as it was not significant, removed it. As an exploratory analysis, we added the socioeconomic status (SES), pain and fibromyalgia to the model.

Results:

A total of 833 patients were analyzed. Baseline characteristics included: female (75%), mean+sd age 53.3+14.2 years, symptom duration 5.9(2.9) months, HAQ 1.1(0.7), swollen joint count 8.1(6.2), tender joint count 8.7(6.7), ESR 27.9 (23.0), CDAI 27.5(14.8).  More than 90% received DMARDs. Methotrexate was used in 74%, steroids in 52% and biologics in only 3% at baseline.  CDAI improved to 12.0(6.2) at 6 mo and HAQ to 0.52(0.6) at 2 yrs. 389 patients (56%) were in LDA at 6 months.

In the multivariate analysis, LDA at 6 mo was a significant predictor of lower HAQ at 2 yrs (p<.0001) (Table). Among additional covariates added in the exploratory analysis, only the presence of fibromyalgia at baseline was associated with higher HAQ at follow-up. 

Conclusion:

LDA as early as 6 mo predicts less future disability. This provides further evidence to support current guidelines recommending early LDA as a desired treatment goal where remission is not possible. Considering that remission is only achieved in a minority of early RA patients, LDA appears to be a more feasible target.

1. S. Akhavan P et al. The impact of reaching low aisease activity in the First year on future disability and damage in patients with early rheumatoid arthritis. Arthritis Rheum, 2012, Supplement, 64(10), S176

Table-Multivariate analysis result. Outcome HAQ at 2 years

Predictor	Estimate	p-value
LDA at 6 mo	-0.27	<.0001
LDA at baseline	0.016	0.83
Age (year)	0.005	0.004
Sex	0.253	<.0001
Symptom duration	0.012	0.12
HAQ*	0.332	<.0001
Rheumatoid Factor	0.078	0.12
DMARD use*	0.017	0.83
Corticosteroid use*	0.071	0.13
Biologics use*	-0.001	0.99
*at BSL

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/reaching-the-target-of-low-disease-activity-at-6-months-predicts-better-long-term-functional-outcome-in-patients-with-early-rheumatoid-arthritis/