Objectives: To assess the validity of the BASRI and m-SASSS scores for the radiological axial involvement in psoriatic arthritis (PsA). Secondary end-points were to report on clinical, functional and radiographic characteristics of axial involvement.
Methods: Inclusion criteria were satisfaction of the CASPAR criteria and the presence of clinical, functional and/or radiological axial involvement. Three observers scored the radiographs by BASRI and m-SASSS. The construct validity was assessed by examining the correlation of instruments with patient reported outcomes and anthropometric measures. The reliability and the feasibility of the scores were also considered.
Results: Seventy-seven patients were enrolled (58 M, 19 F, mean age 49.4 + or - 10.8 yrs, disease duration 13.9 + or - 7.9 yrs). Both instruments showed some modest but significant correlation with clinical measures. When compared, the BASRI showed a correlation with BASMI (rho=0.47, p<0.001), cervical rotation (rho=-0.49, p<0.001), tragus to wall (rho=0.34, p<0.01) and occiput to wall (rho=0.49, p<0.001), modified Schober test (rho=-0.24, p<0.05) and RLDQ (rho=-0.24, p<0.05). When compared, m-SASSS showed a correlation with BASMI (rho=0.39, p<0.001), cervical rotation (rho=-0.41, p<0.001), tragus to wall (rho=0.31, p<0.01) and occiput to wall (rho=0.42, p<0.001), modified Schober and Schober test (rho=-0.34, p<0.001; rho= -0.32, p<0.01), finger to floor (rho=0.37, p<0.01). No correlation was found with BASFI, BASDAI and HAQ. Test-retest showed a good reliability of the scores. Both were feasible but BASRI was the quickest.
Conclusion: Our results showed that BASRI and m-SASSS were valid instruments for use in spondylitis associated with psoriatic arthritis. Longitudinal data is required to provide sensitivity to change of the two scores.