Letter to the editor

To the editor:We thank Dr Falzer for his interest in our recent article on the impact of psychological factors on subjective disease activity assessments in patients with severe rheumatoid arthritis (RA) [1]. We agree that that the Common-sense model (CSM) continues to play a significant role in understanding the impact of illness representations on physical and psychological outcomes in many conditions, including RA [2]. However, his response to the article appears to miss the aim of the reported study. The aim was to investigate the influences of a range of psychological variables on individual components of the DAS28, a widely used assessment of disease activity in RA, rather than to investigate the CSM itself.A change in an individual’s total DAS28 score is often used as an indicator of treatment response. The reported research found that some of the individual components which make up the DAS28, most notably the patient completed visual analogue score of global wellbeing (VAS), may be strongly influenced by psychological factors. The psychological factors we investigated included illnesscognitions and emotional representations (as identified by the CSM and measured using the Brief Illness Perception Questionnaire [3]) as well as depression (measured by the Hospital Anxiety and Depression Scale [4]). In our conclusions we argued that these findings support the case for reporting the individual DAS28 constituents separately. This is important given that current practice uses total DAS28 to guide clinical management. To our knowledge this is the first study to examine the relationships between psychological variables and the individual components which make up the DAS28. We agree with Dr. Falzer that the next logical step is to undertake longitudinal research to identify pathways linking the key variables identified in our article. Findings from that research could then inform clinical practice and guide the development of new interventions to improve outcomes for individuals with RA.