Da. Houssien et al., A patient-derived disease activity score can substitute for a physician-derived disease activity score in clinical research, RHEUMATOLOG, 38(1), 1999, pp. 48-52
Objective. Joint counts have a central role in assessing disease activity i
n rheumatoid arthritis (RA). They are usually undertaken by physicians or n
urses. We investigated whether joint counts can be devolved to patients and
evaluated the use of a patient-derived Disease Activity Score (DAS).
Methods. One hundred RA patients attending a specialist unit were evaluated
, comparing joint counts by a physician with patient-assessed joint counts
and DAS derived from both methods. They were related to other measures of d
isease activity in the European League Against Rheumatism (EULAR) core data
set and with the Rheumatoid Arthritis Disease Activity Index (RADAI; a val
idated patient self-assessment index).
Results. Regression analysis showed no significant differences between a ph
ysician's and patient's joint counts and DAS. There were middle to high cor
relations between patient and physician assessments of tender joints and sw
ollen joints; using R-2, this explained 70% of the variance for tender join
ts and 40% for swollen joints. Kappa analysis showed good agreement between
physician and patient assessments of individual joint tenderness (kappa va
lues 0.49-0.84). There was lower agreement for individual swollen joints (k
appa values 0.02-0.61). Physician DAS and patient DAS had a similar correla
tion with the Health Assessment Questionnaire (HAQ) (r = 0.50 and r = 0.48,
respectively).
Conclusion. The agreements between physician and patient assessments are su
fficient to allow patients' assessments to be used for clinical research. T
his is especially the case with a patient-derived DAS. However, the results
are not directly interchangeable and further studies are needed before pat
ients' assessments are used to guide clinical practice.