SAT0269 Periarticular Bone Gain in Early Psoriatic Arthritis but not in Rheumatoid Arthritis Following Anti-Rheumatic Treatment Assessed By Digital X-Ray Radiogrammetry
Authors: A. Szentpetery, M. Haroon, P. Gallagher, E. Heffernan, O. FitzGerald
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Hand bone loss is an early feature in both RA and PsA, but there is less data available on periarticular bone gain, in particular in PsA following treatment. Digital X-ray radiogrammetry (DXR) is a sensitive method for quantifying changes in periarticular bone mineral density (DXR-BMD) in the early phase of the disease. <h3>Objectives</h3> The aim of this study was to (1) investigate DXR-BMD changes in early PsA and RA prior to and 3, 12 months after introducing an anti-rheumatic drug; and (2) to explore associations between disease-related variables and DXR-BMD. <h3>Methods</h3> Recent-onset (&lt;12 months), active, treatment naïve PsA and RA patients were selected. Hand BMD was measured by DXR based on digitized hand radiographs (Sectra, Sweden) at baseline, 3 and 12 months. Mean DXR-BMD (mg/cm<sup>2</sup>) values of both hands and changes in DXR-BMD (mg/cm<sup>2</sup>/month) were calculated and compared between the two groups at all time points. Changes in hand BMD were further analysed by dividing PsA and RA into 3 subgroups based on cut-offs for the categories normal, elevated BMD loss (&gt;-0.25 mg/cm<sup>2</sup>/month) and highly elevated BMD loss (&gt;-2.5 mg/cm<sup>2</sup>/month). DXR-BMD was correlated with clinical parameters including ESR, CRP, DAS28-CRP4v and HAQ. <h3>Results</h3> 64 patients (32 PsA, 32 RA) were included with median age 43 years. 95% of the patients were commenced on a DMARD therapy at baseline and 11.7 % (12.5% RA; 10.7% PsA) were also started on a TNF inhibitor. There were no patients taking anti-resorptive medications, 17.2% were on oral glucocorticoids (15.6% RA; 18.7% PsA) less than 10 mg per day. At 12 months 94.8% of the patients were on a DMARD and 34.5% on a TNF inhibitor (33.3% RA; 35.7% PsA). Mean DXR-BMD decreased in both diseases at 3 months and was significantly lower in RA at 12 months (p=0.004) compared to baseline. In contrast mean DXR-BMD increased in PsA over 12 months (p=0.07) and was higher at both 3 and 12 months compared to RA. DXR-BMD loss were significantly higher in RA compared to PsA from baseline to 12 months (p=0.0005) and also from 3 to 12 months (p=0.0006). There were no bone loss in 91.7% of patients with PsA, but only in 40.7% of patients with RA between baseline and 12 months. Among all patients with elevated BMD loss, change in DXR-BMD was less marked in the PsA group compared to RA from baseline to 3 (p=0.018) and from 3 to 12 months (p=0.014). Highly elevated bone loss was present only in the RA cohort (7.5%) at 12 months. Disease activity scores were significantly lower in PsA than in RA at baseline and 3 months. ESR, CRP, DAS28-CRP4v improved significantly in both diseases during the study. Mean DXR-BMD correlated negatively with ESR at 12 months in RA (r = -0.39; p= 0.038), however no other significant correlations between other clinical parameters and DXR-BMD were found. <h3>Conclusions</h3> To our knowledge this is the first prospective study showing hand bone loss as early as 3 months measured by DXR in both PsA and RA despite intervention of appropriate anti-rheumatic drug. After 1 year of treatment we observed cortical bone gain in PsA but further bone loss in RA supporting the hypothesis of different pathomechanisms being involved in hand bone remodelling in PsA. <h3>Disclosure of Interest</h3> A. Szentpetery: None Declared, M. Haroon: None Declared, P. Gallagher: None Declared, E. Heffernan: None Declared, O. FitzGerald Grant/research support from: Abbott, BMS, Pfizer, MSD, Consultant for: Abbott, UCB, Pfizer, Speakers bureau: Abbott, Pfizer, MSD