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27-05-2012 | Immunology | Article

Bone loss may herald rheumatoid arthritis diagnosis


Free abstract

MedWire News: Patients with early undifferentiated arthritis (UA) who have radiographic evidence of bone mineral density (BMD) loss in their hands are six times more likely to be diagnosed with rheumatoid arthritis (RA) than those without such bone changes, research suggests.

"Our findings may be relevant for clinical practice, as they may enhance the identification of UA patients that are in an early phase of RA," say Diederik de Rooy (Leiden University Medical Center, the Netherlands) and co-authors.

The team examined data for 517 UA patients attending the Leiden Early Arthritis Clinic, 101 of whom had hand radiographs taken on first visit and again 6 months later.

Digital X-ray radiogrammetry demonstrated highly elevated BMD loss, defined as 2.5 mg/cm2 per month or more in 16% of patients, elevated BMD loss in 46%, and no change in 38%.

"It is interesting to speculate whether BMD loss is due to systemic or to local inflammatory factors," write de Rooy and co-workers.

"The presence of bone metabolism markers in the serum before disease onset at least points to the presence of systemically measurable phenomena."

Twelve months after diagnosis, 53.8% of UA patients had been diagnosed with RA, and 67.5% had persistent disease.

Patients with highly elevated bone loss were 6.1 times more likely to have progressed to RA than those without the BMD changes. Indeed, the BMD loss was 52% sensitive and 95% specific for the diagnosis of RA.

The relationship between BMD loss and RA diagnosis remained even after adjusting for the presence of anticyclic citrullinated antibodies (odds ratio [OR]=4.1), although the researchers note the confidence intervals for this association were large.

After an average of 7 years follow up, the team found that BMD loss was not a significant predictor for persistence of arthritis (OR=0.56).

"It is unknown whether this is due to insufficient power, or whether there is truly no association between BMD loss and arthritis persistency," de Rooy et al comment.

They conclude: "Although more research into the value of BMD loss measurements in early UA is necessary, our study suggests that BMD loss may be a useful prognostic tool."

By Lynda Williams

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