Background Duration of morning stiffness (MS) was part of the American classification criteria for rheumatoid arthritis (RA) (1), but MS was excluded from its recent update and is now regarded as a less valuable measure to assess RA. However, MS is a common symptom associated with RA, Mattila (2) reported that RA-related MS reduces ability of patients to work and contributes to their retirement. Therefore, MS is an important symptom in patients with RA.
Objectives Purpose of our study was investigation of association between MS and disease activity and assessment of ultrasonography (US) in RA.
Methods We conducted a retrospective analysis of 100 consecutive patients with RA (32 males, 68 females; mean age, 63.7±1.1 years; range 35–86 years; mean disease duration, 104±12 months; range 0–564 months). Patients were routinely assessed by US of the wrists, metacarpo-phalangeal and proximal interphalangeal joints. US, estimation of duration of MS (minutes) and clinical and laboratory examinations of all patients were performed on the same day. Patients were divided into the following two groups: “MS positive group” and “MS negative group”, and the US findings, SJC, TJC, CRP, DAS28-CRP, CDAI and SDAI were compared. Prior to US, all patients were checked for clinical disease activity by a consultant rheumatologist. Power Doppler examination was performed by the same rheumatologist. Blood was sampled from each patient by a cannula inserted into the vein on the same day as US and clinical assessment. Blood samples were analysed to determine the serum C-reactive protein level.
Results MS was positive in 38 of 100 patients and the following parameters were significantly higher in the MS positive group as compared with the MS negative group: number of SJC, number of TJC, PGA, EGA, DAS28-CRP, CDAI, SDAI and number of PD signal-positive joints. Number of patients who did not achieve DAS28-CRP, CDAI or SDAI remission was significantly higher in the MS positive group (Table1). By logistic regression analysis, CDAI and number of PD signal-positive joints were associated with presence of MS (CDAI, P=0.0191, 95% confidence interval (CI), −0.50 to −0.05; number of PD signal-positive joints, P=0.0482, 95% CI, −0.78 to −0.02). We performed a receiver-operating characteristic (ROC) analysis to determine if MS could predict the remission of CDAI not being achieved or the presence of PD signal-positive joints in the hand. When cut-off points determined by ROC analysis were applied, MS ≥10 was found to be associated with synovitis in hand, with a sensitivity of 47.5% and a specificity of 92.7% (AUC =0.7438, chi-square test; P<0.0001, 95% CI; 0.6222 to 0.7823), and MS ≥3 was found to be associated with remission of CDAI not being achieved, with a sensitivity of 49% and a specificity of 93% (AUC =0.7087, chi-square test; P<0.0001, CI; 0.6713 to 0.8050).
Conclusions MS is a useful clinical finding for predicting synovitis in hand joints as well as not achieving remission of CDAI in patients with RA.
Arnett FC1, Edworthy SM, Bloch DA, et al. The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis.Arthritis Rheum. 1988; 31:315-24.
Mattila K, Buttgereit F, Tuominen R. Impact of morning stiffness on working behaviour and performance in people with rheumatoid arthritis. Rheumatol Int. 2014; 34:1751-8
Disclosure of Interest None declared