Four-month metacarpal bone mineral density loss predicts radiological joint damage progression after 1 year in patients with early rheumatoid arthritis: exploratory analyses from the IMPROVED study.

AIM To assess whether in early (rheumatoid) arthritis (RA) patients, metacarpal bone mineral density (BMD) loss after 4 months predicts radiological progression after 1 year of antirheumatic treatment. METHODS Metacarpal BMD was measured 4 monthly during the first year by digital X-ray radiogrammetry (DXR-BMD) in patients participating in the IMPROVED study, a clinical trial in 610 patients with recent onset RA (2010 criteria) or undifferentiated arthritis, treated according to a remission (disease activity score<1.6) steered strategy. With Sharp/van der Heijde progression ≥0.5 points after 1 year (yes/no) as dependent variable, univariate and multivariate logistic regression analyses were performed. RESULTS Of 428 patients with DXR-BMD results and progression scores available, 28 (7%) had radiological progression after 1 year. Independent predictors for radiological progression were presence of baseline erosions (OR (95% CI) 6.5 (1.7 to 25)) and early DXR-BMD loss (OR (95% CI) 1.5 (1.1 to 2.0)). In 366 (86%) patients without baseline erosions, early DXR-BMD loss was the only independent predictor of progression (OR (95% CI) 2.0 (1.4 to 2.9)). CONCLUSIONS In early RA patients, metacarpal BMD loss after 4 months of treatment is an independent predictor of radiological progression after 1 year. In patients without baseline erosions, early metacarpal BMD loss is the main predictor of radiological progression.