Background Bone damage, including localized as well as generalized osteoporosis is a well known consequence of the inflammatory arthritides such as rheumatoid arthritis (RA). Psoriatic arthritis (PsA) can be characterized by bone destruction but also new bone formation. In PsA, the literature on osteoporosis is inconclusive and scarcer than in RA.
Objectives To explore if PsA patients are at increased risk of having reduced bone mineral density (BMD) at hip and/or lumbar spine.
Methods Consecutive patients from an outpatient clinic fulfilling CASPAR criteria for PsA were enrolled. We excluded PsA patients with only axial manifestation without peripheral arthritis. All patients underwent a thorough examination according to an extensive protocol. Data collection included demographics, clinical and laboratory disease measures, treatments, and previous fracture history. BMD was measured at spine (L1-4) and hip (femoral neck and total hip) by dual energy X-ray absorptiometry (DXA, Lunar Prodogy). Calibration of the DXA machine was stable during the whole measurement period. BMD was expressed as g/cm2, Z-score and T-score. The percentage of patients with T-score ≤ -2.5 SD (WHO osteoporosis definition) and with Z-score ≤ -1.0 SD was calculated. Appropriate descriptive statistics was applied for continuous and categorical variables.
Results Patient characteristics among the 141 examined PsA patients (men 50.4%): mean (SD) age 52.5 (9.9) years, body mass index (BMI) 28.3 (4.4) kg/m2, disease duration 8.9 years (6.8) and current smoker 17.0%. Median (range) 68 tender joint count was 6.0 [0-55], 66 swollen joint count 0 [0-6] and CRP 2.0 [0-63] mg/dl. Mean (SD) DAS28 was 3.2 (1.2), ESR 15.9 (11.9) mm/hr, MHAQ 0.44 (0.40) and pain and fatigue on visual analogue scale 35.1 (23.5) and 45.7 (32.4) mm respectively. Biologic DMARDs were used by 33.3%, synthetic DMARDs by 56.7% and glucocorticosteroids by 9.9%. Only 11.3% of patients were using calcium and vitamin D supplementation and 2.1% antiresorptive osteoporosis treatment. Low energy fracture was reported in 8.9% of the patients. In the table below mean (SD or 95%CI) bone density values expressed as BMD, Z-score and T-score and percentage of patients with T-score ≤ -2.5 SD and Z-score ≤ -1.0 SD (by definition 16% in the reference population) is displayed. As shown the proportion of patients with Z-score ≤ -1.0 SD was comparable with the 16% seen in the reference population database.
Conclusions The proportion of PsA patients with osteoporosis in our study was low. Overall BMD was comparable to that from normative bone density reference values.
Disclosure of Interest G. Haugeberg Grant/research support from: Unrestricted Grant from Pfizer, B. Grandaunet: None declared, H. Høiberg: None declared, A. Diamantopoulos: None declared, A. Kavanaugh: None declared
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