Background Rheumatoid arthritis (RA) is chronic inflammatory disease that causes joint deformity. Rheumatologists pay much attention in major part to disease activity control that might reflect inflammation of the joint, therefore in main strategy for RA treatment, namely treat to target (T2T) recommended to use composite index that can evaluate disease activity. However, in not a few cases, composite indices cannot indicate for appropriate evaluation. In many part of these cases, patient's pain does not settled down. Pain control is known as closely related with patient's global assessment (PGA). However, pain level is not included in the index. We have investigated the effect of pain control on disease activity and Health Assessment Questionnaire Disability Index (HAQ-DI) statistically.

Objectives Patient's pain is important in treatment of rheumatoid arthritis. We have investigated the effect of pain control on disease activity control and Health Assessment Questionnaire Disability Index (HAQ-DI) control.

Methods 416 patients have followed up more than three years continuously since we adopted Treat to Target (T2T) protocol. From these patients, clinical parameters such like evaluator's global assessment (EGA), PGA, tenderness joint count (TJC), swollen joint count (SJC), C-reactive protein (CRP), and patient's pain score with visual analogue scale (PS-VAS), were measured for every visited times and at the same time, HAQ-DI was measured as status of activity of daily living (ADL). These data were used in this study.

Average value of such as EGA, PGA, TJC, SJC, CRP, SDAI, PS-VAS, matrix metalloproteinase-3 (MMP-3), rheumatoid factor (RF), anti-cyclic citrullinated protein antibody (ACPA), Sharp/van der Heijde Score (SHS), patient's age per each treatment year were calculated for every another treatment year. And the relationship between HAQ-DI and every each of components were evaluated statistically with linear regression analysis. Also relationship between PS-VAS and each of these parameters were also evaluated with linear regression analysis. From results of these analyses, significant parameters were picked up for each of HAQ-DI and PS-VAS, then multiple regression analyses were performed with such parameters. Statistical evaluation was performed with cut off point within 1%.

Results PGA, age and PS-VAS have demonstrated as the only factors that correlated significantly with HAQ-DI throughout every year period. PS-VAS had demonstrated significant close correlation with PGA and TJC.

However with multiple linear regression analysis, HAQ-DI had demonstrated significant close correlation with age, SHS, and PS-VAS. HAQ-DI have not correlated with SDAI, but correlated with PGA, and TJC. PS-VAS correlated significantly with HAQ-DI, SHS, PGA, TJC, and MMP-3.

Conclusions These results suggested that pain is very important to control both of HAQ-DI and disease activity. Pain is not influenced by age. Pain is independent factor that influences on HAQ-DI. Pain has closely correlated with patient's disease status. Therefore pain control is much as important as disease activity control for managing patient's ADL. We need to measure PS-VAS for evaluation of disease control of RA.

Disclosure of Interest None declared