Pediatric Rheumatology Online Journal → June 2003 → Health-Related Quality of Life, Disease Activity and Outcome Assessments→ Abstract #41

THE RESPONSIVENESS-RETROSPECTIVE COEFFICIENT (RRC) AS AN ALTERNATIVE MEASURE OF RESPONSIVENESS: ANALYSIS OF A COHORT OF CHILDREN WITH JUVENILE IDIOPHATIC ARTHRITIS (JIA)

R. Gutierrez-Suarez,¹ I. Pelaez-Ballestas,¹ A. Hernandez-Garduno,¹ H. Arreola-Hernandez,² J. Garduno-Espinoza,² R. Burgos-Vargas.¹

¹Research Division, Hospital General de Mexico, Mexico, DF, Mexico; ²Economical Research Unit, Instituto Nacional del Seguro Social, Mexico, DF, Mexico

Introduction: The effect size (ES) and standardized mean response (SMR) are used as measure of responsiveness in therapeutic trials. ES and SMR value in non-controlled conditions appear limited. In such a case, the RRC calculation may be appropriate.
Objective: To evaluate the RRC as measure of responsiveness in children with JIA attending the every-day clinic and compare it with ES and SMR.
Methods: Data from a cohort of 50 consecutive, out-patients with JIA at baseline and weeks 26 and 54 were evaluated. Analysis was based on all six variables considered in the JIA American College of Rheumatology definition of improvement (ACR-DI).
Statistical analysis: RRC was defined as the mean change of patients who improved standardized to the variability in scores among those with no change. ES and SMR were defined as the mean change score based on comparison of individual scores before and after treatment divided by the standard deviation of the change scores. A fixed effects model (FEM) by linear regression analysis, which considered the variables that actually changed, was carried out for comparisons of RRC, ES, and SMR.
Results: Responsiveness of variables measure by ES and SMR showed no statistically significance in the FEM. The global medical assessment of disease activity, the parents global assessment of overall well-being, the number of joints with limited range of motion and the level of C-reactive protein were responsive variables measured with RRC (1.12) and statistically significance (p=0.03) in the FEM. The number of active joints and the functional capacity measured by CHAQ were no responsive variables by the RRC and the FEM at 26 and 54 weeks.
Conclusions: RRC is an alternative statistical approach to measure responsiveness in the every day clinic. In non-controlled conditions the ES and SMR are certainly limited.