Association of Lupus Nephritis With Coronary Artery Disease by ISN/RPS Classification: Results From a Large Real‐world Lupus Population

OBJECTIVE: Patients with systemic lupus erythematosus (SLE) are at an increased risk for developing coronary artery disease (CAD). Several studies suggest that the presence of lupus nephritis (LN) is independently associated with CAD. The purpose of our study was to assess whether the presence of LN is independently associated with CAD in our patient population and whether this association varies by class of LN. METHODS: A retrospective cross‐sectional analysis was performed using medical records of patients 18 years and older with SLE at University of North Carolina Hospitals from April 4, 2014, to December 31, 2017. Subjects were identified using International Classification of Diseases, Ninth Revision (ICD‐9) and International Classification of Diseases, 10th Revision (ICD‐10) codes specific for SLE. LN class was defined by International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification. CAD was the outcome of interest. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Our sample consisted of 3732 patients with SLE, of whom 598 (16%) had LN and 537 (14%) had CAD. When adjusting for demographics and factors associated with CAD and LN, the odds of having CAD were significantly higher for patients with SLE and LN compared with patients without LN (OR 1.47; 95% CI 1.07‐2.02; P = 0.017). Controlling for these factors, class III LN (OR 1.98; 95% CI 0.95‐4.12; P = 0.069) and class III/V LN (OR 2.23; 95% CI 1.09‐4.62; P = 0.028) were very strongly associated with CAD in subjects with LN compared with subjects without LN. CONCLUSION: We confirm the observations of previous studies that LN is significantly associated with CAD. Our study is the first to show the association between CAD and specific classes of LN.