Background The DAS-28 is the most commonly used score to assess rheumatoid disease activity. It is a composite score based on four variables: tender joint count, swollen joint count, acute phase response and a patient global health assessment on a visual analogue score (VAS). A survey of rheumatologists in our region demonstrated that in clinical practice patients are often asked to score this verbally (audio scale 0-100) as a surrogate to the VAS. The assumption is that there would be no difference between the two values but is that truly the case?
Objectives The aim of this study was to investigate correlation between DAS-28 values calculated with a VAS and DAS-28 derived from an audio score.
Methods Patients with rheumatoid arthritis attending for regular follow-up were asked to assess their global health on a VAS and also to score their health verbally (audio score). One of the questions was asked at the start of the consultation and another at the end. The order of the questions varied between the patients. The individual values of the VAS and audio scores were then used to calculate two separate DAS-28 results for each patient. The DAS-28 results were then compared with each other to see if there was any meaningful difference between values calculated depending on the method used to assess global health. If there was a difference we proceeded to see if this could have affected clinical management. This was conducted across two hospitals.
Results Data was obtained from 59 patients. In four patients (6.78%) the two DAS-28 values differed depending on the global health measurement. In three (5.08%) of those patients standard DAS-28 indicated low disease activity whereas audio DAS-28 indicated remission. In one patient (1.69%) the difference of 0.17 between the two DAS-28 values corresponded to the difference between moderate disease activity (standard DAS-28) and high disease activity (audio DAS-28). However the difference between the scores did not affect clinical management in any of these patients. The difference between the two sets of DAS-28 values in our cohort of patients was not statistically significant (p-value =0.25).
Conclusions In our study there is no significant difference in DAS-28 values derived from the standard validated VAS approach as compared to those from an audio score. This is reassuring and supports the use of the audio score as a convenient alternative to the VAS in routine clinical practice. However, the values that patients give for an audio score tend to be round numbers so one should consider reassessment with VAS if the initial audio derived DAS-28 result is borderline across disease activity states.
Disclosure of Interest None declared