Rheumatoid factor measurement--continuing problems 70 years after discovery Clinical Rheumatology, 04/11/2011

Ameratunga R et al. – Standardization for rheumatoid factor (RF) measurement is not optimal and has not been achieved between these two commonly used instruments. This may have clinical implications for patient management.

• Compared RF results between 2 commonly used commercial instruments
• Serum samples exchanged between laboratory using Beckman Immage immunonephelometer and another using Roche Modular immunoturbidimeter
• The World Health Organization (WHO) reference standard for RF (W1066) used to compare 2 methods

• The Roche immunoturbidimeter appears to have superior sensitivity
• Significant bias between 2 instruments as levels of RF increase
• Results from WHO RF reference preparation correlated most closely with results from Roche immunoturbidimeter