Primary ankylosing spondylitis: Patterns of disease in a Brazilian population of 147 patients

Objective. To analyze patterns of disease in a population of Brazilian pati ents with primary ankylosing spondylitis (AS). Methods. Retrospective study (1988-98) analyzing 147 patients with a diagno sis of primary AS according to the modified New York criteria. Selected pat ients had complete clinical (initial symptom, axial and peripheral involvem ent, heel enthesitis, extraarticular manifestations) and radiological (sacr oiliac, lumbar, thoracic, and cervical spine) investigations, and these dat a were compared with sex, race, age at onset, and HLA-B27. Results. There was a predominance of men (84.4%), Caucasian race (75.5%), a dult onset (> 16 years, 85%), and positive HLA-B27 (78.2%). Family history of AS was noted in 14.3% of the patients. Pure axial AS was observed in 37 patients (25.2%). The predominant initial symptoms were inflammatory low ba ck pain (61.9%) and peripheral arthritis (22.4%). Thoracic and cervical spi ne involvement was noted in 70.1% of the patients; radiological findings in cluded syndesmophytes in 46.9% and "bamboo spine" in 20.4% of patients. The extraaxial joints most frequently involved were: ankles (39.5%), hips (36. 1%), knees (29.3%), shoulders (19%), and sternoclaviculars (14.3%); heel en thesitis was present in 22.4%. Acute anterior uveitis was noted in 14.3% of patients. Male sex was associated with involvement of thoracic spine (p = 0.002), cervical spine (p = 0.002), and hips (p = 0.042), whereas female se x was associated with sternoclavicular (p = 0.024) involvement. Caucasian r ace presented higher frequency of positive family history (p = 0.023); ther e was no statistical significance of clinical and radiological variables co mpared with African-Brazilians. Juvenile onset AS presented higher frequenc y of ankle (p = 0.012) and knee (p = 0.001) involvement, heel enthesitis (p = 0.001), and total hip replacement (p = 0.038), whereas adult onset was a ssociated with thoracic (p = 0.026) and cervical spine (p = 0.026) involvem ent and positive family history (p = 0.044), Positive HLA-B27 was associate d with ankle involvement (p = 0.007) and heel enthesitis (p = 0.013). Conclusion. In this population women showed a milder axial involvement, Cau casian race presented axial and peripheral involvement similar to African-B razilians, juvenile onset AS was associated with articular involvement of t he lower limbs, and positive HLA-B27 was associated with ankle involvement.