Clinical comparison of patients with ankylosing spondylitis, Reiter's syndrome and psoriatic arthritis

Between 1976 and 1989, 160 cases of seronegative spondyloarthropathy (SNSA) were admitted to the Department of Medicine at Chulalongkorn Hospital. The prevalence of idiopathic ankylosing spondylitis (IdAS) was 52 cases (32.5%), Reiter's syndrome (RS) 68 cases (42.5%), psoriatic arthritis (PsA) 28 cases (17.5%), reactive arthritis eight cases (5.0%) and Behcet's disease four cases (2.5%). Clinical comparison of the patients with IdAS, RS and PsA showed a male predominance in IdAS (90.2%), RS (97.1%) and PsA (71.4%). There was a significant difference (p < 0.01) between IdAS and PsA, and RS and PsA. The initial articular manifestation usually occurred in the younger age group (IdAS, 22.15; RS, 22.91; and PsA, 30.86 years); however, there was a significant difference (p < 0.05) between IdAS and PsA, and RS and PsA. Initial peripheral arthritis was found in IdAS (51.9%), RS (91.2%) and PsA (92.6%); there was a significant difference (p < 0.001) between IdAS and RS, and IdAS and PsA. The symptom of back pain was found in IdAS (78.8%), RS (38.2%) and PsA (21.4%); there was a significant difference (p < 0.001) between IdAS and RS, and IdAS and PsA. During physical examination, peripheral arthritis was evident in the IdAS (42.2%), RS (88.2%) and PsA (92.2%) patients; likewise sacroiliitis was found in the IdAS (100%) RS (54.4%), and PsA (57.2%) patients. Evidence of ankylosing spondylitis was found in the IdAS (100%), RS (22.1%) and PsA (46.4%) patients. These findings show a significant difference (p < 0.001) between patients with IdAS and RS, IdAS and PsA. Other associated symptoms were similar, particularly evidence of enthesopathy (tendonitis, heel pain, plantar fasciitis), the polyarticular pattern was more common than the mono-articular pattern. Hip joint was significantly (p < 0.05) more commonly involved in patients with IdAS than in those with RS and PsA. Associated symptoms, particularly genital lesion or skin lesion, are specific symptoms for RS and PsA, respectively.