title: Prevalence of spondylarthropathies in HLA-B27 positive and negative blood donors.
abstract: OBJECTIVE
  To determine the overall prevalence of spondylarthropathy (SpA) among whites.
  
  
  METHODS
  To screen for SpA symptoms, such as inflammatory back pain (IBP), joint swelling, psoriasis, and uveitis, or a specific family history, questionnaires were mailed to 348 blood donors (174 HLA-B27 positive and 174 HLA-B27 negative). From the responding 273 persons (78%; 140 B27 positive, 133 B27 negative), 126 were selected for further evaluation based on the symptoms reported. Of this group, 90 persons agreed to undergo physical examination (71.4%; 46 B27 positive, 44 B27 negative). There was no difference between the B27-positive and -negative groups in terms of age (mean +/- SD 38.4 +/- 10 versus 39.5 +/- 11 years) and sex ratio (67% versus 68% were men). In addition, 58 donors (32 B27 positive, 26 B27 negative) agreed to undergo magnetic resonance imaging (MRI) of the sacroiliac joints. A diagnosis of SpA and ankylosing spondylitis (AS) was made according to the European Spondylarthropathy Study Group criteria and the New York criteria.
  
  
  RESULTS
  SpA was diagnosed in 20 persons: 19 of 140 B27-positive (13.6%) and 1 of 133 B27-negative (0.7%) subjects (15 male and 5 female). AS was diagnosed in 9 persons (7 male and 2 female; 45%), undifferentiated SpA (USpA) in 7 (5 male and 2 female; 35%), psoriatic arthritis (PsA) in 3 (2 male and 1 female; 15%), and chronic reactive arthritis (ReA; Reiter's syndrome) in 1 (male; 5%). On the basis of a B27 frequency of 9.3% among the population of Berlin (3.47 million persons), the estimated prevalence of SpA was 1.9%, AS was 0.86%, USpA was 0.67%, and PsA was 0.29%. The relative risk of developing SpA in B27-positive subjects was calculated as 20.7 (95% confidence interval 4.6-94.2; P = 0.001). Of 58 persons with IBP, sacroiliitis was detected by MRI in 15 of 32 B27-positive (46.9%) and 1 of 26 B27-negative (3.9%) subjects (P = 0.002). Four of these 16 donors did not fulfill diagnostic criteria for SpA.
  
  
  CONCLUSIONS
  With a calculated prevalence of 1.9%, spondylarthropathies are among the most frequent rheumatic diseases in the white population. HLA-B27 positive persons carry a 20-fold increased risk of developing SpA. AS and USpA are the most frequent SpA subtypes. Persons with IBP who are B27 positive have a 50% likelihood of having sacroiliitis.
authors.affiliation: Klinikum Benjamin Franklin Free University, Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Braun
authors.forename: M
authors.initials: M
authors.lastname: Bollow
authors.forename: G
authors.initials: G
authors.lastname: Remlinger
authors.forename: U
authors.initials: U
authors.lastname: Eggens
authors.forename: M
authors.initials: M
authors.lastname: Rudwaleit
authors.forename: A
authors.initials: A
authors.lastname: Distler
authors.forename: J
authors.initials: J
authors.lastname: Sieper
mesh_terms: D000328:Adult; D001604:Berlin / Q000453:epidemiology; D001782:Blood Donors; D005260:Female; D015796:HLA-B27 Antigen / Q000097:blood*; D006801:Humans; D007592:Joint Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology; D008279:Magnetic Resonance Imaging; D008297:Male; D008487:Medical History Taking; D008875:Middle Aged; D010808:Physical Examination; D015995:Prevalence; D000091402:Prohibitins; D012216:Rheumatic Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology; D012446:Sacroiliac Joint; D013122:Spinal Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology; D011795:Surveys and Questionnaires; D044465:White People
chemical_list: D015796:HLA-B27 Antigen; C000717331:PHB2 protein, human; D000091402:Prohibitins