Profile of HLA-B27-related 'unclassifiable' seronegative spondyloarthropathy in females and its comparison with the profile in males.

Unclassifiable seronegative spondyloarthropathy (SSA) syndrome is primarily considered to be an affliction of males. In this report from northern India, 25 HLA-B27 antigen positive females with this condition are described and compared with 39 HLA-B27-positive males with the same disease. All these patients presented with typical features of spondyloarthropathy such as predominantly lower limb synovitis, enthesopathy and inflammatory spinal pain. The onset was insidious in 56% of the females and in 64% of the males. The mean age of onset as also the mean duration of symptoms prior to diagnosis were significantly higher in females (26.2 vs 19.4 yr and 8 vs 2 yr, respectively). A mono- or oligo-arthritis was seen in 52% of the females and in 53% of the males, but the average number of joints involved was less in females (4.8 vs 7.7). Lower limb joints alone were involved in 56% of the females and 49% of the males, with the knees, ankles and hips being most commonly involved, often asymmetrically. The mean degree of symmetry was significantly lower in females (62 vs 76). Ninety-two per cent of females and 74% of males had inflammatory spinal pain. Radiographic sacroiliitis was demonstrable in 56% females and 74% males. It is concluded that 'unclassifiable' SSA syndrome is not infrequent in females but is diagnosed late. Fewer joints tend to be involved and there is greater tendency towards asymmetry in females.