Prediction of disease progression in early rheumatoid arthritis by ICTP, RF land CRP. A comparative 3-year follow-up study

Objective. To test the predictive value of the cross-linked carboxyterminal telopeptide of type I collagen (ICTP; a marker of type I collagen degradat ion), rheumatoid factor (RF) and C-reactive protein (CRP) for disease progr ession in patients with early rheumatoid arthritis (RA) Method. We tested the value of baseline values of RF, CRP and ICTP for the prediction of radiological joint progression over 3 yr in 63 consecutive pa tients with early RA who were treated with the 'saw-tooth strategy'. Results. Age- and sex-adjusted risks as odds ratios (95% confidence interva ls) of elevated serum ICTP, RF positivity and increased CRP for progressive joint disease (defined as an increase of >20 in Larsen's index on radiogra phs of the hands and feet) were 3.9 (1.3, 11.9), 3.9 (1.0, 15.5) and 2.6 (0 .9, 7.5), respectively. Better prediction was achieved when the tests were used in combination, and where there was both elevated ICTP and positive RF the odds ratio was 9.1 (2.5, 32.9). This test combination showed good sens itivity and specificity (71 and 77%, respectively), with a positive predict ive value of 65% and a likelihood ratio of 3.1. Conclusion. This kind of risk profile, in which the tests used reflect diff erent aspects of the disease process, may be useful in early disease assess ment to find patients who will need the most active drug therapy.