Background/Purpose: The ACR/EULAR Boolean definition of remission is expected to be used as an outcome measure in randomized clinical trials for rheumatoid arthritis (RA).  Boolean defined remission requires satisfaction of all of the following: (TJC≤1, SJC≤1, CRP≤1 mg/dl and patient global assessment (PGA) ≤1 (0-10 scale) (1).The extent to which PGA may be driven by the presence and the duration of morning stiffness and thus the ability to meet Boolean based remission criteria has not been investigated. 

Methods: Patients enrolled in the Corrona RA registry were analyzed. Data from the most recent visit for the components of Boolean remission criteria were used.  The percentage of patients in Boolean based remission was calculated. Morning stiffness data (presence or not, and duration) as reported by the patient at each registry visit were utilized.  We investigated the prevalence and the duration of morning stiffness in RA patients in remission and for those not meeting the remission criteria due to PGA>1 while all other components (TJC, SJC, CRP) were ≤1.

Results: Out of 24,170 patients, Boolean defined remission was met in 4,856 (20.09%) patients at the most recent visit. Boolean remission was not met in 19,314 (79.91%) patients and 4,371 (18.08%) patients did not meet remission criteria due to PGA>1. Morning stiffness was present in 39.4% of patients in remission (and PGA≤1) while it was reported in 78.4% of patients not in remission because PGA>1 (p<0.001). The median duration of stiffness at most recent visit was 0.33(IQR: 0.17-0.5) hours for patients in remission while it was 0.75(0.33-1.5) hours for patients not in remission because of PGA>1(p<0.001). 8.9% of patients had morning stiffness >1 hour in the former group while 26.3% of patients reported a similar duration in the latter group (p<0.001). 

Conclusion: PGA may be affected by several factors and may not allow patient to meet remission criteria based on the Boolean definition.  In this analysis, 18.08% of patients did not meet remission criteria because PGA>1. Morning stiffness duration was longer in these patients compared to patients in remission. This finding suggests that morning stiffness is an important contributor to the PGA and likely plays a role in patients’ inability to meet the remission criteria.

Reference: 1. Bykerk VP, Massarotti EM. The new ACR/EULAR remission criteria: rationale for developing new criteria for remission. Rheumatol 2012;51 :vi16–vi20.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-influence-of-patient-reported-morning-stiffness-on-patient-global-assessment-in-rheumatoid-arthritis-patients-not-achieving-acreular-boolean-remission-in-a-large-us-registry/