Serum Osteoprotegerin Level as a Risk Factor for Atherosclerosis in Systemic Lupus Erythematosus Patients: A Cross Sectional Study

Abstract

Background: Prediction ofthe risk of atherosclerosis in Egyptian patients with systemic lupus erythematosus (SLE) by measuring serum osteoprotegerin (OPG) level and correlation between OPG levels and SLE disease activity (assessed by Systemic Lupus Erythematosus Disease Activity Index [SLEDAI] score), is the aim of this study. Methods:A cross sectional study in which all patients were subjected to full medical history, full clinical examination (with special emphasis to SLE symptoms and signs e.g. photosensitivity, arthralgia, arthritis, malar rash, blood pressure and lower limb edema), laboratory investigations (CBC, random blood sugar [RBS], ESR, albumin/creatinine ratio, serum urea and creatinine, serum albumin, C3, total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, calcium and phosphorus). Electrocardiography (ECG) was done to calculate QTc interval using Bazett’s formula: QTC = QT / √ RR. Serum osteoprotegerin level was measured using ELISA technique. All participants were subjected to imaging in the form of: Carotid duplex: to assess intima-media thickness just two cm before carotid bifurcation, and to assess any plaques, if present. Also brachial artery flow mediated dilatation method: for detection of subclinical atherosclerosis. Results: There was a statistically significant negative correlation between serum levels of osteoprotegerin and brachial flow mediated dilation percentage (FMD %) values (P value > 0.001) which means a significant correlation between high serum OPG levels and subclinical atherosclerosis in SLE patients. There were statistically significant differences between SLE cases and controls in right and left carotid intima-media thickness (P value: 0.034 & 0.036 respectively), serum osteoprotegerin levels (P value: > 0.001) and QTc values (P value: 0.011) which were all statistically significantly higher in SLE patients, while brachial FMD % was statistically significantly lower in SLE patients than in controls (P value: > 0.001). Also, there was a statistically significant positive correlation between serum OPG levels and QTc interval (P value: 0.006). Conclusion: We have concluded that serum OPG level has a significant correlation with subclinical atherosclerosis and endothelial dysfunction, which was measured by CIMT and brachial mediated flow dilation method.