Background Osteonecrosis of the femoral head (ONF) occurs frequently (3-40%) in patients who are treated with corticosteroids for SLE, and it seems to be important to detect early changes in the femoral head by MRI and early clinical events caused by steroid therapy. For treatment of SLE, several strategies have been selected according to the clinical conditions of patients, and there are slight differences between multicenter hospitals. However, in studies performed at single hospital, the treatment strategy, selection of steroid, initial dose of steroid and drugs used together with steroid have been quite similar. In addition, the speed at which the steroid has been tapered off has also been quite uniform. Therefore, it should be possible to clarify the background factors associated with ONF.
Objectives To clarify the factors related to early change of ONF in patients with SLE.
Methods Seventy-seven patients (8 males and 69 females) with SLE were selected on the basis of having been newly diagnosed and requiring high-dose prednisolone, including pulse therapy with methylprednisolone, as the initial treatment. All the patients initially underwent plain radiography and MRI at three months after the start of treatment with corticosteroids to detect any early changes in the femoral head. Subsequently these examinations were performed three months thereafter. The laboratory parameters were evaluated at the beginning of steroid treatment and at one month thereafter. All statistical analyses were performed with SPSS v. 13 (SPSS Inc., Chicago, IL, USA). Tests were 2-tailed, and differences at p<0.05 were considered significant.
Results By three months after the start of corticosteroid treatment, ONF was diagnosed by MRI in 21 patients (27.3%), being bilateral in 11 patients and unilateral in 10. Clinical features, Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), serological activity (C3, C4, CH50 and anti-ds DNA antibody) and renal function (eGFR, serum creatinine and urinary protein) were not correlated with ONF. In addition, anti-phospholipid antibodies were not correlated with ONF. Body mass index (BMI), Body serfece area (BSA), and the initial dose of prednosolone per unit body weight, BMI and BSA were not correlated with ONF. However, habitual cigarette smoking tended to increase the incidence of ONF. The total cholesterol level at 4 weeks after the start of steroid treatment tended to be higher in patients with ONF but the levels of LDL-C and HDL-C were not correlated with ONF. Patients with a higher triglyceride level showed a significantly higher frequency of ONF (P-0.001).
Conclusions ONF is common in patients with SLE. A high triglyceride level is an important risk factor for ONF, and large epidemiologic surveys are necessary to prevent early events such as ONF in patients receiving steroid therapy.
Acknowledgements This study was supported by a research grant from the Research Committee on Idiopathic Osteonecrosis of the Femoral Head of the Ministry of Health, Labour, and Welfare of Japan.
Disclosure of Interest None declared