Background:Chronic rheumatological manifestations similar to those of rheumatoid arthritis (RA) have been described after chikungunya virus infection. However, the clinical significance of the symptoms and disease severity in the two conditions has not been directly compared.Objectives:To compare, using identical measures of disease severity and patient outcomes, the impact of disease severity measures and symptoms on outcomes in RA and chronic chikungunya disease.Methods:Forty patients with chronic chikungunya arthralgia two years post-infection and 40 matched patients with RA were enrolled in Roraima, Brazil. Twenty-eight joints were assessed for tenderness and swelling, a pain intensity visual analogue scale, musculoskeletal stiffness questionnaire, modified Health Assessment Questionnaire and the EuroQol EQ5D-5L quality of life assessment were completed. The importance of the various measures of disease severity were analysed using Spearman’s rank correlation and regression analysis.Results:Tender and swollen joint counts, pain and stiffness were all predictive of the HAQ disability index in RA, but only stiffness was significantly associated with disability in chikungunya patients (Table 1). Tender and swollen joint counts, pain and stiffness were predictive for all EQ5D quality of life domains (except anxiety/depression) in RA patients. In contrast, in chikungunya disease, tender joint counts were predictive only of usual daily activities; pain was predictive of impaired mobility, self-care and discomfort, while stiffness was predictive for the mobility and anxiety/depression domains (Figure 1). Swollen joint counts were not associated with any of the patient outcomes in chikungunya disease. Linear regression analysis confirmed (p=0.003) that the effect of swollen joint count on the HAQ disability index depends on the underlying disease.Table 1.Association of disease severity with HAQ disability index in rheumatoid and CHIKV+ arthritisSeverity measureRheumatoid arthritisCHIKV+ arthritisr (p)r (p)Tender joint count0.56 (0.0002)0.24 (0.14)Swollen joint count0.60 (<0.0001)0.002 (0.99)Joint pain (VAS)0.55 (0.0002)0.29 (0.07)Stiffness severity0.57 (0.0001)0.38 (0.02)Figure 1.Association of disease severity with quality of life domains in rheumatoid and CHIKV+ arthritisConclusion:The value of all the disease severity measures tested in RA were confirmed, but tender joint counts may have more limited value in the assessment of chronic chikungunya disease. Joint swelling appears to have little impact for chikungunya patients, while stiffness appears to be an important metric to quantify chikungunya arthritis disease severity.Disclosure of Interests:Hugh Watson Shareholder of: Sanofi, Employee of: Sanofi, Ramão Luciano Nogueira-Hayd: None declared, Maony Rodrigues-Moreno: None declared, Felipe Naveca: None declared, Giulia Calusi: None declared, Richard Amdur: None declared, Karol Suchowiecki: None declared, Gary S. Firestein: None declared, Gary Simon: None declared, Aileen Chang: None declared
