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Sunday 15 September 2019
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In low-prevalence disease, like rheumatoid arthritis, specificity is important


The recommended first-line testing that supports the diagnosis of RA best does include CCP and RF IgM measurements7

However, it’s well established that:

  • Clinical test performance varies by manufacturer
  • The most common marker provided is rheumatoid factor (measuring a mix of isotypes (IgG, IgA and IgM) without characterising individual isotypes) vs. the specific identification of RF IgM

In low-prevalence disease where most tests are expected to be negative, every increase in specificity is important. Higher specificity leads to fewer false positive results.