A study led by Min Kyung Lee, PhD, from Labcorp analyzed over 850,000 IgM tests for rubella and parvovirus B19 between 2014 and 2023 to differentiate early rheumatoid arthritis (RA) from self-limited viral arthritis. Results showed that positive rubella IgM correlated with higher rates of arthritis-related diagnostic coding and RA biomarker positivity, yet did not predict future RA diagnoses. Conversely, parvovirus B19 positivity was linked to a 33% increased risk for subsequent RA suspicion, highlighting B19V's role as a clinical RA mimic rather than a concurrent disease.
1. 2.1% of adults tested positive for rubella IgM. 2. Higher rates of arthritis-related diagnostic codes in IgM-positive adults. 3. Rubella IgM positivity did not predict future RA diagnosis. 4. 2.1% tested positive for parvovirus B19 IgM. 5. B19V IgM positivity linked to a 33% higher risk of future RA suspicion. 6. Patients with prolonged B19V symptoms show no joint erosion like RA. 7. B19V IgM testing needed during acute illness for accurate diagnosis.
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