Background Osteoporosis (OP) and subsequent fragility fractures (FFx) are a common comorbidity in patients with Systemic Lupus Erythematosus (SLE). A chronic therapy with glucocorticoids (GC) is one of the main risk for their development. Due to the severe impairment of the quality of life they could cause, prevention and treatment of OP is a central issue in the management of SLE.
Objectives In this work we aimed at evaluating (i) the prevalence of OP and clinically evident FFx in a cohort of SLE patients under chronic GC therapy, (ii) the presence of some additional risk factors with identification of possible strategies to improve their quality of care.
Methods The following data were retrospectively collected from clinical charts of SLE patients under regular follow up: age, sex, menopausal status (MP), Body Mass Index, smoking habits, disease duration, daily dose and cumulative GC, presence and type of organ involvement, comorbidities and concomitant medications potentially affecting bone metabolism. Bone Mineral Density (BMD) scores, presence of FFx, phosphocalcic metabolism, supplementation with calcium and vitamin D and therapy with bisphosphonates (BPs) were also recorded. BMD of lumbar spine and non-dominant hip was measured by DXA and expressed as T-scores and in g/cm2. OP was defined according to the World Health Organization. Only FFx occurring after the onset of SLE and unrelated to trauma were included. Univariate and multivariate logistic regression were used to analyze the associations of both OP and FFx with possible risk factors.
Results One hundred and eighty six patients (F 175, M 11; mean age 46.4±13 years, mean disease duration 14.9±9 years, mean fu 11±8 years) were included into the analysis. The mean BMI value was 23,95 kg/m2, 56 (30.1%) were smokers, 68 (36.8%) had a thyroid disorder, 61 women (34.9%) were MP and 26 patients (14%) had a CRF. All patients have been treated with GC: mean daily dose of 5-4±2.3 mg and mean cumulative dose of 34.9±25.3 g (prednisone equivalent). At their last visit, 97 patients (52.2%) had a reduced BMD and 52 (27.9%) had OP. At least one FFx was recorded in 22 out of 186 patients (11.8%); patients with FFx were all women and 6 (27.3%) were pre-menopausal; in 16 cases more than one FFx were present, for a total of 40 fractures. Univariate analysis showed a correlation between OP and age, cumulative dose of GC, MP, therapy with AEDs and with CRF (p<0.03); the multivariate logistic model confirmed a direct association of OP and age, MP and AEDs therapy (p≤0.01). At the univariate analysis, the development of FFx was associated with age, total amount of GC, MP, CRF, AC and AEDs therapy (p<0.05). The multivariate analysis showed age, chronic therapy with AC and with AEDs as the best independent predictors for FFx (p<0,03).
Conclusions In conclusion, low BMD is frequently observed in SLE patients chronically treated with GC, and FFx are observed also in premenopausal patients. Together with well known risk factors (age, MP and GC) CRF and a chronic treatment with AC or AEDs seem to be associated with a higher risk profile for OP and FFx in these patients. Thus, these variables should be considered for a patient's tailored risk stratification and, eventually, for a stricter monitoring or more aggressive treatment strategies.
Disclosure of Interest None declared