Evaluation of the Finnish versions of the functional indices BASFI and DFIin spondylarthropathy

The aim of the study was to compare and evaluate the usefulness of Finnish versions of two functional indices used in spondylarthropathies. Seventy co nsecutive inpatients with different kinds of spondylarthropathies filled in self-administered questionnaires: the Bath Ankylosing Spondylitis Function al Index (BASFI) and the Dougados Functional Index for spondylarthropathies (DFI). Cronbach's alpha as a coefficient of internal consistency was analy sed for BASFI and DFI. Test-retest reliability was evaluated in 30 patients . For validity the functional indices were compared with the Bath Ankylosin g Spondylitis Disease Activity Index (BASDAI), erythrocyte sedimentation ra te (ESR), spinal movement measures of chest expansion (CE), Schober SI test and occiput-to-wall distance (OWD), and radiological changes in the lumbar spine (RTGLS) and sacroiliac joints (RTGSI). The reproducibility of the in dices BASFI and DFI was good; the intraclass correlation coefficient (ICC) for reliability was 0.99 and 0.98, and the coefficient of internal consiste ncy (Cronbach's alpha) was 0.94 for both BASFI and DFI. The functional indi ces correlated well with each other, r = 0.85 (95% CI 0.78-0.90). Validity in terms of correlation coefficients between disease activity index BASDAI and functional indices BASFI and DFI was 0.74 (95% CI 0.60-0.84) and 0.69 ( 95% CT 0.53-0.80), respectively. BASFI and DFI correlated with spinal mobil ity measurements and RTGLS, but DFI did not correlate with RTGSI. Neither B ASFI nor DFI correlated with ESR and disease duration, and only DFI correla ted with age. In conclusion, BASFI and DFI are reliable and valid for Finni sh inpatients with spondylarthropathies. It is important to know that cultu ral differences do not reduce the usefulness of these indices.