Routine Assessment of Patient Index Data 3 (RAPID3) is a Valid Index for Routine Care in Patients with Osteoarthritis

Objective: To compare Routine Assessment of Patient Index Data 3 (RAPID3) on a Multidimensional Health Assessment Questionnaire (MDHAQ) with the Western Ontario and Mc-Master Universities Osteoarthritis Index (WOMAC) in patients with knee or hip osteoarthritis and to evaluate its reliability. Methods: 678 patients with hip or knee osteoarthritis were assessed in daily practice clinical care during 2009-2013. Patients completed an MDHAQ and so a RAPID3 was calculated (physical function, pain, patient global estimate). Pain, stiffness, and physical functions using the standard WOMAC indices for hip and knee osteoarthritis were assessed too; correlation between WOMAC total scores and RAPID3 scores were estimated with Spearman’s rho. Furthermore a linear regression model was developed with a coefficient of determination R2. Finally we evaluated validity and reliability of this index to evaluate that RAPID3 is not inferior to WOMAC. Results: RAPID3 and WOMAC were correlated significantly, with a global correlation Spearman’ rho index of 0.84 (P<0.01). Computing analysis for diagnosis the correlation index was 0.83 for hip osteoarthritis (p