Background/Purpose:

Clinical remission is the treatment target in rheumatoid arthritis (RA) and several composite indices are available for evaluation of remission and low disease activity (LDA) states. We currently have little information on how disease duration impacts remission and LDA rates in daily clinical practice. We examined how often clinical remission and LDA is achieved in clinical practice using existing definitions in RA patients with variable disease duration.

Methods:

Data were retrieved from the NOR-DMARD register. For the present analyses we used data from all 4568 patients starting with a synthetic (n=3095) or biological (n=1473) DMARD with available a 3-month follow-up data, and also from 3262 patients with available 6 months follow-up data. Mean (SD) age was 54.7 (13.7) yrs, disease duration was 8.5 (7.9) yrs, 72.7% of patients were females.

Applied definitions for clinical remission included the Disease Activity Score based on 28 joint counts (DAS28) <2.6, the Simplified Disease Activity Index (SDAI) <3.3, the Clinical Disease Activity Index (CDAI) <2.8, Routine Assessment of Patient Index Data (RAPID3, range 0-10) <1, and the ACR/EULAR remission definition (A/E) with tender joint count, swollen joint count, patient global assessment (scale 0-10), and CRP (mg/dL) all <1. We also explored a practical remission definition of A/E without CRP (A/E PRAC), and low disease activity for DAS28 (<3.2), SDAI (<11), CDAI (<10) and RAPID3 (<2). The four investigated categories for disease duration were: <1 year, 1<6 years, 6-10 years, and >10 years.

Results:

The table shows percentages for patients according to disease duration periods who met different remission and LDA definitions after 3 months and 6 months of DMARD treatment.

While the new A/E remission criteria were most stringent, for all remission indices the likelihood of remission after 3 and 6 months of DMARD treatment decreased with increasing RA disease duration (Chi square test p<0.01 for all comparisons for 3 and 6 months follow-up). Remission and low disease activity rates after 3 and 6 months were clearly best in patients with up to one year disease duration. Only 6-9 percent of patients with disease duration over 1 year achieved after 3-6 months DMARD treatment a state of remission according to the A/E criteria.

Disease duration (yrs)	All	<1	1-<6	6-<10	>10	All	<1	1-<6	6-<10	>10
	Remission 3 months (%)					Remission 6 months (%)
DAS28	21.2	26.3	19.9	16.9	18.1	24.7	31.7	20.8	23.5	19.6
SDAI	8.9	12.6	7.6	7.7	6.0	10.8	14.4	10.2	8.8	8.0
CDAI	9.5	12.9	8.2	8.4	6.8	11.4	15.4	10.3	9.7	8.4
RAPID3	19.4	25.5	17.0	19.2	14.0	20.1	26.0	20.0	18.0	14.2
A/E	8.0	11.0	6.8	6.5	5.7	9.4	11.6	9.0	8.0	7.7
A/E PRACT	9.5	12.9	8.6	7.9	6.9	11.3	14.3	10.1	9.8	9.1
	LDA 3 months (%)					LDA 6 months (%)
DAS28	34.0	39.9	32.2	30.5	30.3	39.7	47.5	38.0	35.0	34.3
SDAI	40.5	46.9	38.3	37.2	36.4	46.7	55.1	45.1	42.7	40.3
CDAI	41.0	47.0	38.5	37.4	37.9	47.3	55.0	45.8	43.2	41.6
RAPID3	38.7	46.8	36.6	36.3	32.4	40.7	48.5	40.2	37.7	33.6

Conclusion:

The target of remission varies in difficulty across different remission criteria and is less often achieved with increasing disease duration. These observations have implication for how treat-to-target can be managed in a realistic way in patients with established disease and may indicate that many patients with established disease will need an individualized target due to joint destruction, co-morbidities and other factors.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/remission-is-a-difficult-target-in-clinical-practice-when-ra-disease-is-established/