Morning stiffness (MS) is a complex symptom involving pain and functional
limitation. It is not included in the ACR/EULAR
2010 classification criteria for rheumatoid arthritis (RA) nor is a component of
Disease Activity Scores, which generally serve as the primary outcome measures
to assess efficacy of therapies for RA. However, this symptom at
first presentation is a risk factor for more severe disease reflected by
structural damage or disease persistence. Despite this, the
best way to evaluate morning stiffness has been controversial.

Background/Purpose:
To compare the severity and duration of MS, assessed by physician and by a
self-report questionnaire, with disease activity and functional disability in a
cohort of patients with RA.

Methods:
We conducted a cross-sectional observational study that included consecutively
patients with established RA (ACR 1987 criteria) from two rheumatology centers.
Patients were assessed for MS: approximately half of them were asked about
the duration (in minutes)  and the rest of them  were evaluated using a self
reported questionnaire which included the intensity (VAS) and duration (in
minutes and Likert Scale) of MS. Physician global assessment, pain and global
status by VAS, functional disability (HAQ-DI), tender and swollen joint count
(total of 28), erythrocyte sedimentation rate and disease activity (DAS28 and
CDAI) were evaluated. Regression models were used to estimate possible
associations between these variables and morning stiffness.

Results: One
hundred and eleven patients were included, 88% were women (n=96). Mean age was
52 years (SD 13) and median disease duration was 8 years (IQR 4-12). Fifty
seven patients (51%) reported MS, 27 out of 52 were asked by the physician and
30 out of 59 were assessed by the questionnaire. MS measured
in minutes by the physician showed a significant correlation with functional
disability scores HAQ-DI (r= 0.72, p<0.001), whereas there was an acceptable
correlation (r=0.61, p<0.001) between DAS28 and severity of MS measured by
VAS (TABLE). When intensity of MS was evaluated by VAS (assessment in
both numerical and non-numerical scales), we observed  that a value ³ 5.5
centimeters (0-10) was associated to severe disease activity (DAS28 > 5.1) with
a sensitivity of 44% and specificity of 100% (AUC 0.76).

Conclusion:
Duration of morning stiffness evaluated through patient interview appears
to reflect functional disability while the severity of morning stiffness was
associated more strongly with inflammatory activity in this cohort of RA
patients.

      Table:  MS correlation (assessed by different methods) with DAS28, CDAI and HAQ-DI 

     
*p < 0.05