Background Morning stiffness is common in Rheumatoid Arthritis (RA). It has been part of the classification criteria for decades but is not part of the 2010 criteria for RA. Nevertheless, information on morning stiffness is still used in daily practice in the diagnostic process. Surprisingly, large-scale studies on the value of morning stiffness are lacking. We aimed to further establish the diagnostic and prognostic ability of morning stiffness in patients with arthralgia and with early arthritis by evaluating data of 4,991 patients included in 5 data sets.
Objectives We aimed to determine: (1) whether morning stiffness is valuable in patients with arthralgia to identify patients with arthritis, (2) whether morning stiffness in patients is helpful in differentiating RA from other forms of early arthritis, (3) whether within RA morning stiffness is associated with an unfavourable disease course and (4) which duration of morning stiffness has an optimal discriminative ability for diagnosis.
Methods Arthralgia patients referred to the Early Arthritis Recognition Clinics (EARC) of Leiden (n=865) and Groningen (n=212) and to the REACH-study (n=353, Rotterdam) were studied; the outcome of this cross-sectional comparison was the presence of arthritis at physical examination. Early arthritis patients included in the Leiden Early Arthritis Clinic (n=2748), and ESPOIR (n=813) were studied on developing RA (fulfilling the 2010 criteria within the first year). The long-term outcomes DMARD-free sustained remission and radiological progression over 7 and 2-years were studied in 2010-RA patients included in the Leiden EAC (n=1073) and ESPOIR (n=645). Morning stiffness was present in case the duration was ≥60 minutes. Sensitivity analyses were performed for other durations and for the severity (visual analogue scales). The duration that had the optimal discriminative ability was determined using ROC-curves.
Results Morning stiffness (≥60 minutes) was associated with the presence of arthritis in arthralgia patients in the Leiden EARC OR1.55 (95%CI 1.05-2.29), Groningen EARC OR1.73 (0.80-3.75) and REACH OR1.61 (1.02-2.54). When investigating morning stiffness in early arthritis, it was found that patients that developed RA more often suffered from morning stiffness (OR in Leiden EAC 3.07 (2.61-3.61), in ESPOIR 2.28 (1.55-3.34)), also after adjustments for age, gender, ACPA, RF, SJC and ESR (Leiden EAC OR 1.75 (1.34-2.28), ESPOIR OR 1.68 (1.03-2.74)). Sensitivity analyses on ≥30 and ≥90minutes or using VAS morning stiffness yielded comparable results. Among the arthralgia patients and the early arthritis patients the AUCs were low, the optimal discriminative ability of morning stiffness for diagnosis was around 30 minutes. Morning stiffness was not associated with radiological progression or DMARD-free sustained remission.
Conclusions Morning stiffness in arthralgia and early arthritis is independently associated with arthritis and RA-development respectively. These data support the incorporation on information on morning stiffness in the diagnostic process in daily clinical practice.
Disclosure of Interest : None declared