Characterization of bone metabolism in hungarian psoriatic arthritis patients: a case-control study.

Background: Skeletal manifestations are predominant in psoriatic arthritis (PsA). The aim of this cross-sectional, case-control study is the complex assessment of areal and volumetric bone mineral density (BMD), fracture risk, vitamin D status and bone turnover markers, and its association with disease-related variables.

Methods: Lumbar spine (L1-L4) and femoral neck (FN) areal, and distal radius (DR) volumetric BMD, 10-year probability of major and hip osteoporotic fracture as assessed by the fracture risk assessment (FRAX) tool, markers of bone metabolism and disease activity were assessed.

Results: Upon comparison of the disease and age- and sex-matched control groups, there was a statistically significant difference in FN areal (0.952 (0.607-1.292) g/cm2 vs. 1.016 (0.760-1.550) g/cm2; p = 0.001) and DR total volumetric (284.3 (138.9-470.3) mg/cm3 vs. 367.0 (287.0-412.0) mg/cm3; p < 0.001) BMD, 10 year probability for major osteoporotic (3.7% (0.7-32%) vs. 2.6% (0-17.5%); p = 0.003) and hip (0.4% (0-16%) vs. 0.05% (0-6.1%); p = 0.002) fracture and 25-hydroxyvitamin D status (47.5 (10-120) nmol/L vs. 64 (10-137; p < 0.001) nmol/L). As compared to areal assessment, volumetric BMD measurements identified a significantly higher number of patients with low bone mineral density (T-Score ≤ - 1.00) (34% vs. 88%, p < 0.001). Upon multiple linear regression analysis, disease activity score, as determined by DAS28 assessment, was an independent predictor of 10-year probability for major osteoporotic fracture (B (95%CI) = 1.351 (0.379-2.323); p = 0.007).

Conclusions: In the studied PsA cohort, disease activity was an independent predictor of 10-year probability for a major osteoporotic fracture, and complemented assessment of volumetric and areal BMD assured better efficacy at identifying those with low bone mineral density.