RESEARCH - Prediction models for RA: evaluation of combinations of RF, anti-CCP and the HLA SE

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Ann Rheum Dis. 2006 Jul 13; [Epub ahead of print]

Prediction models for rheumatoid arthritis during diagnostic workup:

evaluation of combinations of rheumatoid factor, anti-citrullinated

protein/peptide antibodies and the HLA shared epitope.

Vander Cruyssen B, Hoffman IE, Peene I, Union A, Mielants H, Meheus L, De

Keyser F.

UZ Gent, Belgium.

OBJECTIVES: A prediction model for a disease may depend on the studied

population. In the present analysis, our objective was to calculate the

probabilities for rheumatoid arthritis (RA) in a consecutive cohort of

patients during diagnostic work- up. Therefore, we fitted different logistic

regression models evaluating the value of HLA-shared epitope (SE)

determination and testing for rheumatoid factor (RF) and anti-citrullinated

protein/peptide antibodies (ACPA). METHODS: The study included 1003

consecutive patients, presenting a new diagnostic problem for which RA was

included in the differential diagnosis. All patients were tested for ACPA,

RF and HLA-SE. RESULTS: After 1 year, diagnoses were established: 153

patients had definite RA and 629 patients had RA excluded. RF, used as a

continuous marker is useful to evaluate the probability for RA. Combined RF

and SE testing, or combined ACPA and RF testing, provided additional

predictive information. The redundancy of SE testing in a model that

includes ACPA testing can be explained by the high association between ACPA

and SE both in RA and non-RA patients. The value of RF testing increased if

patients presented with at least one swollen joint at baseline.

CONCLUSION: In the present study, we calculated valid probabilities for RA

during routine diagnostic work-up and showed that the potential additional

value of SE testing disappears when ACPA testing is available. Combined RF

and ACPA testing is useful, especially when RF is considered as a continuous

parameter reflecting an increasing probability for RA at higher RF titers.

The value of (continuous) RF testing increases when the a priori chance is

higher.

PMID: 16840502

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=PubMed & list_uids=1\

6840502

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