Background: Osteoporosis is commonly seen in patients with Systemic Lupus Erythematosus (SLE), even in pre-menopausal patients. The etiology is multifactorial and chronic glucocorticoid therapy seems to play a central role.

Objectives: To investigate the ten-year risk of fracture assessed by Fracture Risk Assessment Tool (FRAX), with and without dual-energy X-ray absorptiometry (DXA) and to determine possible demographic or clinical factors associated with an increased risk of fracture in a SLE population.

Methods: Retrospective study including all the over 40 years-old patients with the diagnosis of SLE (2012 SLICC classification criteria) followed at our Rheumatology Department registered in our national database. Demographic, clinical and laboratorial data were collected at the last follow-up visit. Data from the last DXA (until 3 years prior to the last visit) were collected. Indication for pharmacological treatment by FRAX was assessed according to the national recommendations: estimated fracture risk, without DXA, ≥11% for major osteoporotic fracture or ≥3% for hip fracture and/or estimated fracture risk, with DXA, ≥9% for major osteoporotic fracture or ≥2.5% for hip fracture.

Results: We included 104 patients, 101 (97.1%) females, aged 54.5±9.9 years, with a median disease duration of 19.3 years [4.3-51.6]. Twelve patients (11.5%) were current smokers, 31 (29.8%) had elevated anti-dsDNA antibodies (≥100 IU/mL) and 27 (26.0%) had complement consumption (C3c<83mg/dL or C4<12mg/dL). 73 patients (70.2%) were taking glucocorticoids with a mean daily prednisolone equivalent dosage of 4.4±5.2 mg/day. Regarding SLE treatment, 69 patients (66.3%) were under hydroxychloroquine, 22 (21.2%) under azathioprine, 16 (15.4%) under mycophenolate mofetil, 5 (4.8%) under belimumab, 4 (3.8%) under methotrexate, 1 (1.0%) under leflunomide and 1 (1.0%) under rituximab.

Ten patients (9.6%) had previous fragility fractures, 54 patients (51.9%) had DXA in the last 3 years and 81 (77.9%) were taking calcium and/or vitamin D supplements.

Sixteen (15.4%) had indication for treatment by FRAX without DXA and 8 of these (50%) were under treatment. Moreover, thirteen (12.5%) had indication for treatment by FRAX with DXA and 8 of these (61.5%) were under treatment.

Five patients (4.8%) were reclassified in FRAX with DXA: 3 patients (2.9%) had no indication for treatment by FRAX without DXA but conquered it by FRAX with DXA and 2 patients (1.9%) had indication for treatment by FRAX without DXA but lost it by FRAX with DXA. We found a good level of agreement in the indication for treatment between FRAX with and without DXA (kappa=0.741; p<0.001).

There was no significant difference in the risk of fracture estimated by FRAX with or without DXA, both for major osteoporotic fracture and for hip fracture. Correlations between fracture risk and some clinical variables can be seen in table 1 .

Conclusion: A higher number of patients had indication for pharmacological treatment by FRAX with DXA in comparison with FRAX without DXA. However, we found no statistically significant difference in the estimated fracture risk with and without DXA. This, together with the good level of agreement between FRAX with and without DXA, suggests that the fracture risk estimation, even without DXA, may be an appropriate approach. The low number of patients with indication for pharmacological treatment by FRAX, with and without DXA, may be explained by their low mean age and the high number of them under vitamin D/calcium supplementation.

Disclosure of Interests: Bruno Miguel Fernandes: None declared, Salomé Garcia: None declared, Sara Ganhão: None declared, Maria Rato: None declared, Filipe Pinheiro: None declared, Miguel Bernardes Speakers bureau: Abbvie, Amgen, Biogen, Eli-Lilly, Glaxo-Smith-Kline, Pfizer, Janssen, Novartis, Lúcia Costa: None declared