Background The aim of rheumatoid arthritis (RA) treatment is to optimize symptom control and, when possible, achieve sustained remission. Therefore, identification of clinical signs predicting future remission is valuable to clinical decision making. One question faced by clinicians is whether the achievement of a lower disease activity value or a higher rate of change of disease activity is indicative of better future disease outcomes.
Objectives To determine whether change in disease activity measures or the actual values achieved at 6 months were more predictive of remission at 12 months in RA patients treated with infliximab (IFX) in a real-world, clinical practice setting.
Methods BioTRAC is an ongoing, prospective registry of patients initiating treatment for RA with IFX or golimumab as first biologics or after having been treated with a biologic for <6 months. Eligible people for this study included RA patients treated with IFX enrolled between 2002-2012 with available 12-month information on remission. Multivariate logistic regression models with the parametric Wald statistic and the log-likelihood ratio were used to assess the independent contribution of the actual value and the change at 6 months in predicting 12-month remission as defined by DAS28 (<2.6), SDAI (≤3.3) and CDAI (≤2.8) criteria. These two statistics assess the extent of contribution of an individual predictor to an outcome of interest - higher values signify greater contribution - and can be used to compare the contribution of different predictors in a standardized fashion.
Results 436 patients were included with mean age of 56.1 yrs and disease duration of 10.4 yrs. With respect to 12-month DAS28 remission, a stronger association was observed with the actual DAS28 score compared to the percent improvement in DAS28 at 6 months. The Wald statistic for the percent change and actual value of DAS28 at 6 months was 5.38 and 46.88, respectively, while the change in log-likelihood was 4.98 (P=0.026) and 61.64 (P<0.001), respectively, indicating that the actual DAS value achieved is significantly more predictive of remission when compared to percent change in DAS from baseline.
For SDAI remission at 12 months, the respective Wald values for percent change and actual value at 6 months were 0.075 and 18.28 and log-likelihood changes were 0.07 (P=0.788) and 24.08 (P<0.001). For CDAI remission at 12 months, the Wald statistic was 0.01 and 34.42 for 6 month percent change and actual value, respectively, and change in log-likelihood was 0.01 (P=0.934) and 34.23 (P<0.001). Similar results were obtained when predicting low disease activity at 12 months.
Conclusions These results demonstrate that the actual disease outcome value achieved at 6 months is a stronger predictor of remission at 12 months than the percent change in disease activity. These findings suggest that the treatment target in a real-world setting should be set as specific endpoints and not as change over time.
Disclosure of Interest : None declared