Use of exploratory factor analysis to ascertain the correlation between the activities of rheumatoid arthritis and infection by human parvovirus B19

Background and objective: We evaluated a possible correlation between the clinical activities of rheumatoid arthritis (RA) and human parvovirus B19 (B19) infection using exploratory factor analysis (EFA).
Materials and methods: RA patients were organized into two groups: 100 patients in the main groupand97intheRA(DAS28)group.Foursubgroupsweredefinedfromthemaingroupaccording to the presence or absence of certain infection-specific markers: group I comprised 43 patients whohadIgGantibodiesagainstB19;groupII,25patientswithactiveB19infection(B19-specificIgM antibodies and/or plasma viremia); group III, 19 patients with latent/persistent B19 infection (virus-specific sequences in peripheral blood leukocytes' DNA with or without B19-specific IgG antibodies), and group IV, 13 patients without infection markers. The RA(DAS28) group was divided into four subgroups similarly to the main group: group I, 35; group II, 31; group III, 19; and group IV, 12 patients. Disease-specific clinical values in both groups were analyzed employing EFA, and the RA(DAS28) group was additionally assessed using Disease Activity Score (DAS)28. Results: RA activitywashigherinpatientswhohad markersofB19infection.Thehighestactivity of RA in both study groups was in patients with latent/persistent infection. In the RA(DAS28) group, according to DAS28, the highest activity of RA was in patients with active B19 infection. Conclusions: Using EFA and DAS28, a correlation between the clinical activity of RA and B19 infectionwasconfirmed.ThesedatasuggestthatEFAisapplicableformedico-biologicalstudies.