Background/Purpose:
28 joints-disease activity score (DAS28) is routinely used in clinical practice
to assess disease activity in rheumatoid arthritis (RA). DAS28, particularly
its subjective components [patient visual analogue scale (VAS), tender joint count
(TJC)] might not always reflect inflammation. No study to date has assessed the
relationship between PRO and the DAS28 components in a large cohort of
patients, among different countries. The main objective of this study is to
assess the associations between patient and physician reported outcomes and the
objective components of DAS28 across different geographical populations, using
the COMORA dataset¹(‘Prevalence of Comorbidities in Rheumatoid Arthritis and
evaluation of their monitoring: results of an international, cross-sectional
study’). The study will also assess the relationship between patient and
physician perception of disease activity, and PRO and number of comorbidities.

Methods:
Demographics, clinical characteristics, including DAS28 and PRO, treatment and
comorbidities were recorded. Using Spearman’s rho, we assessed pairwise
correlations among patient global, patient fatigue, physician global, quality
of life (EQ5D) and the DAS28 components for each country. We then looked at the
inter-relationship of patient/physician reported outcomes. Finally, the correlation
between PRO and comorbidities was calculated.

Results:
3674 patients from 17 countries were included in the analysis (mean age 56
years; 82% female). Mean (SD) DAS28 was moderate at 3.72 (1.55). DAS28, SJC,
TJC and ESR varied significantly between countries. ESR showed very weak
correlation with all PRO for the majority of the countries. SJC correlated
moderately with PRO and the association varied between countries, but showed
good correlation with physician global for almost all assessed countries(r>0.5
for 16/17). TJC had good correlation with patient global, physician global and
EQ5D and showed little variation between countries. TJC and patient fatigue
correlation varied between countries. Patient and physician global correlated
with each other. No significant correlation was found between number of
comorbidities and PRO.

Conclusion:
PROs generally associated well with the more subjective components of DAS28
whilst physician global seemed more consistent with the objective elements and
this was observed across most countries. Geographical variation however was
particularly observed with tender joint and patient-reported fatigue. This
might have implications in the interpretation and applicability of
International clinical trials.

References: 1.Dougados M, Ann Rheum Dis, 2014

Table 1: Ranges of Spearman’s rho coefficients