Background Patient-reported outcomes such as pain and patient global assessment of disease activity (PtGA) have been critiqued for not accurately assessing RA disease activity as they may reflect aspects not directly related (e.g. fibromyalgia, low back pain, depression) or related to non-RA conditions.
Objectives To describe the relationship between patient-reported pain and RA disease activity levels in a real-world, routine clinical care setting; To assess the occurrence of non-remission driven solely by pain using PtGA as a proxy for pain.
Methods BioTRAC is an ongoing, Canadian prospective registry of rheumatology patients initiating infliximab (IFX) or golimumab. Data from RA patients treated with IFX between Jan 2002 and Jun 2011 were used. Correlation of pain (VAS mm) with DAS28-ESR, CDAI and SDAI in a continuous or binary (low disease activity: yes vs no; remission: yes vs no) scale was assessed with linear regression and logistic regression, respectively. For assessment of non-remission due to PtGA, DAS28-ESR, CDAI, and SDAI, remission rates were compared to “non-PtGA” remission rates, calculated by subtracting the relative contribution of PtGA to the index.
Results Analyses included 838 RA patients with 4,582 assessments. A significant (P<0.001) positive linear relationship was found between pain and DAS28-ESR (standardized coefficient (β) = 0.662), CDAI (β = 0.660), and SDAI (β = 0.659). Increased pain was associated with reduced odds of achieving remission or low disease activity as defined by DAS28-ESR, CDAI, and SDAI (Table 1). Correlation analysis showed a strong positive linear correlation existed between pain and PtGA (r = 0.914), supporting the use of PtGA as a proxy for pain. Cross-tabulation of remission achievement with “non-PtGA” remission achievement revealed that omission of PtGA from the DAS28-ESR, CDAI, and SDAI indices would result in the re-classification of an additional 2.0%, 9.3%, and 9.6% of the cases as remission.
Conclusions Increased pain is associated with higher disease activity as measured by the DAS28-ESR, CDAI and SDAI, which may be due to the strong correlation of pain with PtGA. Omission of PtGA from these indices resulted in classification of additional cases as remission cases to an extent that paralleled the strictness of the remission criteria (i.e., from the less “strict” DAS28-ESR to the more “strict” SDAI). Therefore, the CDAI and SDAI might be more sensitive to pain not directly related to RA.
Disclosure of Interest R. Arendse: None Declared, M. Starr: None Declared, P. Rahman: None Declared, J. Kelsall: None Declared, M. Baker: None Declared, W. Bensen: None Declared, C. Thorne: None Declared, P. Baer: None Declared, D. Choquette: None Declared, I. Fortin: None Declared, E. Rampakakis Employee of: JSS, J. Sampalis Employee of: JSS, S. Otawa Employee of: Janssen, M. Shawi Employee of: Janssen, F. Nantel Employee of: Janssen, A. Lehman Employee of: Janssen