Association of rubella and parvovirus B19 IgM positivity and suspected rheumatoid arthritis: a retrospective analysis from a large US national reference laboratory (2014–2023)

OBJECTIVE: Rubella and parvovirus B19 (B19V) infections can present with arthritis-like symptoms in adults instead of typical dermatological symptoms. We quantify associations between rubella and B19V, respectively, with arthritis-like complications using real-world diagnostic testing. DESIGN: Cross-sectional and retrospective cohort study. SETTING: Reference laboratories across the USA. PARTICIPANTS: Participants with IgM tests for rubella (N=211 917) or B19V (N=644 473) performed at Labcorp from 2014 to 2023. Among these participants, participants with IgM tests for rubella (N=1867) or B19V (N=22 683) and longitudinal laboratory testing through Labcorp were followed for diagnostic tests for rheumatoid arthritis (RA) up to 1.5 years after the viral IgM tests. PRIMARY AND SECONDARY OUTCOME MEASURES: Primary outcomes were arthritis-like suspicions by providers and diagnostic testing for RA-associated biomarkers. RESULTS: Higher proportions of suspicions of arthritis (1.4%, p