ABSTRACT
BACKGROUND: The nomination of undifferentiated spondyloarthropathy (USpA) has provided clues for the early diagnosis of spondylitis ankylopoietica and other subsets of SpA, thereby avoiding possible wrong treatments.OBJECTIVE: To investigate the prevalence of SpA in the workers and their adult relatives aged over 16 years old from a factory in Beijing urban district, as well as the results of human major histocompatibility complex (MHC) B27 and X-ray inspection on sacroiliac joint.DESIGN: Systematic sampling investigation.SETTING: Department of Internal Medicine, Chenghai District People's Hospital of Shantou City; Rheumatism Research Institute, Medical College of Shantou University; Department of Internal Medicine, Beijing Chaoyang Hospital.PARTICIPANTS: A survey was conducted among 1982 workers and their adult relatives aged over 16 years from a factory in Beijing urban district between May and October 1999; there were 1,025 males and 957 females.They all volunteered into this study after informed of the experiment.METHODS: All examinees were surveyed door to door with the modified Chinese-International Anti-rheumatic Alliance Rheumatism Questionnaire,those with positive results were subjected to physical examination and those suspicious cases were subjected to MHC-B27 and X-ray examination.MAIN OUTCOME MEASURES: The prevalence of SpA in the workersand their adult relatives aged over 16 years from a factory in Beijing urban district, as well as the results of MHC-B27 and sacroiliac joint X-ray inspection.RESULTS: Totally 1,982 subjects were enrolled in this study and all entered the result analysis. The prevalence of spondyloarthropathy was 1.61%(32/1 982), amongst which the prevalence of ankylopoietic spondylitis,USpA, and psoriastic arthritis was 0.31% (6/1 982), 1.21% (24/1 982),and 0.10% (2/1 982), respectively. No other subsets of SpA were observed. USpA was mainly presented by inflammatory lumbago and asymmetric arthrosteitis [83% (20/24), 62% (15/24)], while rheumatoid factor was negative in all subjects. Meanwhile, MHC-B27 was proved positive in 25% (6/24) subjects with the male-to-female ratio of 1.2:1.CONCLUSION: The prevalence of SpA is 1.61% in Beijing urban area,and SpA mainly consists of ankylopoietic spondylitis and USpA.