Table 2 Demographic data in patients with AS, suspected sacroiliitis and controls with MLBP
AS*Suspected sacroiliitis†MLBP, control group‡
Number of patients36125560
Disease duration in years8.03.05NA
% male patients71.7%55.5%50.0%
Mean age (range)33.2 (26.7–40.3)35.0 (27.5–45.3)29.5
HLA-B27 positive75.7%68.0%8.6%
  • AS, ankylosing spondylitis; MLBP, mechanical low back pain; NA, not available.

  • *AS: information about disease duration given in six studies,23 28 34 37 46 48 about gender distribution in nine studies,28 34–38 40 46 48 about age given in 10 studies,23 28 3438 40 46 48 and about HLA-B27 in seven studies.23 24 28 35 37 38 47

  • †Suspected sacroiliitis: information about disease duration given in two studies (mean disease duration 2.3 years53 and 3.8 years46), about gender distribution in five studies,29 42 44 51 53 about age in five studies,29 31 46 51 53 and about HLA-B27 in five studies.24 29 42 50 52

  • ‡MLBP, control group: information about gender distribution given in two studies,38 42 about age given in one study,38 and about HLA-B27 in three studies.38 42 49