ASSESSMENT OF OSTEOPOROSIS IN PSORIASIS WITH AND WITHOUT ARTHRITIS: CORRELATION WITH DISEASE SEVERITY

Background: The most frequent extracutaneous medical problem associated with psoriasis is arthritis. Patients with psoriatic arthritis (PsA) may have local and systemic bone loss, and thus, may be at increased risk of osteoporotic fractures. The exact cause of osteoporosis in PsA patients is still not well defined. Based on increased proinflammatory cytokines in psoriasis, we hypothesized that psoriatic patients are more prone to osteoporosis than healthy subjects. Besides, other potential factors, that could contribute to bone loss in PsA, include chronic inflammation, medications, and prolonged immobilization due to joint dysfunction and severe pain. Osteoprotegrin (OPG) or osteoclast differentiation-inhibiting protein would suppress osteoclastogenesis, so, it may play a role in osteoporosis. Objectives: To assess osteoporosis in psoriatic and psoriatic arthritis (PsA) patients, by dual energy x ray absorptiometry (DEXA), and measuring serum osteoprotegrin level, and to correlate these findings with the extent of both skin and joint manifestations. Methods: 50 psoriatic patients (16 of them had arthritis) were assessed by psoriasis area and severity index (PASI). Total joint score was used to assess joint manifestations in PsA patients. Bone mineral density was measured at the femoral neck, lumbar spine and wrist using DEXA for all patients and 20 age and sex matched controls. Serum OPG level was measured by enzyme linked immunosorbent assay to all patients and controls. Results: Serum OPG level was significantly increased in both psoriatic patients (21.14±8.62 pg/ml) and PsA (22.68±7.04 pg/ml) in comparison to controls (7.65±3.32 pg/ml) (p<0.001), while, there was no statistically significant difference in serum OPG between psoriatic patients with and without arthritis (p=0.77). The radiological assessment of osteoporosis by DEXA revealed statistically significantly lower T and Z score of lumbar spine, neck of femur, and wrist in either psoriatic or PsA patients compared to controls (p<0.05). However, PsA patients had more significant osteoporosis in neck of femur and wrist as detected by significantly lower T score in these sites(-1.08±1.7 and -1.87±1.72 respectively) compared to psoriatic patients (-0.35±1.32 and -1.17±1.28 respectively) (p=0.012 andp=0.001 respectively), and significantly lower Z score in the same sites (-1.03±1.35 and -2.03±1.35 respectively) compared to psoriatic patients (-0.36±1.14 and -1.14±1.26 respectively) (p=0.026 and p=0.036 respectively). In PsA patients, total joint score was positively correlated with both disease duration (r =0.53, p=0.03), and extent of skin involvement as measured by area score of PASI (r =0.62, p= 0.01), but negatively correlated with Z score in neck of femur (r =-0.5, p=0.04). Conclusion: Psoriatic patients with or without arthritis could suffer from osteoporosis as evidenced by significantly increased serum OPG level. However, PsA patients had more significant osteoporosis in neck of femur and wrist as detected by DEXA. Prolonged and extensive cutaneous disease is an important risk factor for the development and severity of PsA. Patients with more number of affected joints are at higher risk of osteoporosis. Disclosure of Interest: None declaredCitation: Annals of the Rheumatic Diseases, volume 69, supplement 3, year 2010, page 578Session: Psoriatic arthritis (Poster Presentations )