OSSIFICATION OF THE POSTERIOR LONGITUDINAL LIGAMENT IN 3 GEOGRAPHICALLY AND GENETICALLY DIFFERENT POPULATIONS OF ANKYLOSING-SPONDYLITIS ANDOTHER SPONDYLOARTHROPATHIES

Study design-Cross sectional. Research questions-(a) Is any clinical v ariable of ankylosing spondylitis (AS) associated with the presence of ossification of the posterior longitudinal ligament (OPLL)? and (b) I s OPLL present in patients with AS from different geographical or gene tic backgrounds? Methods-Three groups were assembled: (1) a prospectiv e group of 103 consecutive AS patients from two community based rheuma tology clinics from Guadalajara, who were evaluated using: a questionn aire with disease characteristic variables; clinical assessment by a n eurologist; lateral radiographic views of the cervical spine and somat osensory evoked potentials (SSEP). (2) Fifty one spondyloarthropathies (SpA) patients from Mexico city whose cervical spine films were retro spectively reviewed. (3) Thirty nine AS patients from Edmonton, Canada whose cervical spine films were retrospectively reviewed and compared with 72 controls. Results-Group 1: 74% of the 103 patients were men a nd 86% were HLA-B27 positive. The mean age was 35 years, and mean (SD) disease duration 10 (8) years. OPLL was reported in 16 patients (15.5 %; 95%C I 9, 22). OPLL was statistically associated with older age (p= 0.001), longer disease duration (p=0.001), clinical myelopathy (p=0.03 ), worst functional index (p=0.042), restricted axial movement measure ments (all p<0.001), radiological sacroiliitis (p<0.001 for linear ass ociation), osteitis pubis (p=0.009), hip involvement (p=0.006 for line ar association), and abnormal SSEP (p=0.008). Group 2: 92% of 51 patie nts were men; the mean age was 30 years and the mean (SD) disease dura tion 11 (7) years. OPLL was reported in 15 (29%, 95%CI 17, 41) patient s (nine AS, two psoriatic arthritis, three juvenile AS, and one Reiter 's syndrome). Group 3: 95% of the 39 patients were men; the mean of ag e was 46 years and disease duration of 18 (10) years. OPLL was reporte d in nine (23%; 95%CI 10, 36) patients, including one with psoriatic a rthritis, and two with Crohn's disease. OPLL was observed in two of th e control group. Conclusions-The prevalence of OPLL in AS and SpA is h igher than previously recognised and seems to be associated with varia bles identifying more severe axial disease.