A proposal for the classification of patients for clinical and experimental studies on reactive arthritis

To propose classification criteria for patients entering clinical and basic studies on reactive arthritis (ReA).

From a MEDLINE search of articles published between 1980 and 1996, we identified reports on HLA-B27 related ReA and Reiter's syndrome as study groups and analyzed the items that constituted the diagnostic, classification, and inclusion (or entry) criteria of patients. We developed disease categories that constituted our classification proposal.

We reviewed 175 articles containing 110 study groups of patients with ReA and 94 with Reiter's syndrome. Most articles (89.7%) relied on arthritis for diagnosis, but only 48.0% relied on infection. Only 22.5% of articles used published criteria for diagnosis. Articles including a bacterial name to further describe a group of patients with ReA relied on cultures at the site of infection, serum antibodies, or both to confirm the diagnosis. There were inter/intra-group variations and overlapping of diagnostic criteria, at least 32 different terms referring to ReA or Reiter's syndrome, and 6 patterns of disease. According to these data, we propose 3 categories of disease for patients entering clinical and basic studies on ReA: probable ReA (2 subgroups); definite ReA triggered by bacteria (2 subgroups); and bacterial-associated undifferentiated oligoarthritis or spondyloarthropathy.

This proposal provides a rationale for reducing the heterogeneity found in criteria for including patients with ReA in research and to facilitate scientific communication. In contrast to diagnostic criteria, this proposal does not restrict the study population to a minority of patients, but allows the investigator to include several forms of disease and to analyze results according to different categories.