Relationship between spinal mobility and disease activity, function, quality of life and radiology. A cross-sectional Spanish registry of spondyloarthropathies (REGISPONSER).

OBJECTIVE To determine the relationship between anthropometric measurements and disease activity, functional capacity, quality of life and radiology in Spanish patients with ankylosing spondylitis (AS). PATIENTS AND METHODS A cross-sectional study was made of 842 patients with definite ankylosing spondylitis (REGISPONSER). Sociodemographic data, spinal mobility measurements, Bath AS disease activity index (BASDAI), nocturnal pain, Bath AS radiology index (BASRI), Bath AS functional index (BASFI), the Short-Format 12 (SF-12) and the AS specific quality of life (ASQoL) questionnaire were applied. Pearson correlation coefficient analysis and regression models were constructed. RESULTS There was moderate correlation between fingertip-to-floor distance and lateral cervical rotation with the BASFI (p<0.01). Good correlation was evident between wall-occiput distance and lateral cervical rotation with the BASRI (p<0.01). Moderate correlation was found between chest expansion, the Schober modified test and fingertip-to-floor distance with the total BASRI (p<0.01). The anthropometric measurement with the lowest correlation value was lateral lumbar flexion. Significant association was found between the Schober modified test and BASFI, BASDAI and BASRI (R(2) = 0.37; p<0.001); chest expansion and BASFI, BASDAI and BASRI (R(2) = 0.25; p<0.001); wall-occiput distance and BASFI, BASRI and ASQoL (R(2) = 0.44; p<0.001); fingertip-to-floor distance and BASFI and BASRI (R(2) = 0.30; p<0.001); and lateral cervical rotation and BASFI and BASRI (R(2) = 0.34; p<0.001). CONCLUSION In our study, wall-occiput distance and lateral cervical rotation showed the strongest correlation to BASRI. Similarly, fingertip-to-floor distance and lateral cervical rotation exhibited the closest correlation to BASFI.