Relationship of anemia with disease activity and renal damage in patients with systemic lupus erythematosus

Objective To explore the relationship of anemia with disease activity and renal damage in patients with systemic lupus erythematosus(SLE).Methods A total of 187 SLE patients and 187 healthy controls were recruited for this retrospective study.The prevalence of anemia was compared.They were divided into three groups of mild anemia,moderate-severe anemia and non-anemia based upon level of hemoglobin(Hb)and severity of anemia.According to renal function state,they were also classified as two subgroups of renal insufficiency anemia and renal normal anemia.Clinical parameters of Hb,complement C3/C4,C-reactive protein(CRP),urea,creatinine,uric acid,24-hour urine protein and systemic lupus erythematosus disease activity index(SLEDAI)were collected and compared.Spearman's correlation analysis was performed for evaluating the correlations between anemia and various clinical parameters.Multivariate Logistic regression was utilized for analyzing the risk factors for SLE disease activity and renal damage.Receiver operating characteristics curve(ROC)was employed for evaluating the predictive value of Hb for SLE disease activity and renal damage.Results The prevalence of anemia was 52.41% in SLE patients and it was significantly higher than that in healthy control group(P<0.05).As compared with SLE non-anemia group,C3 decreased markedly while CRP,SLEDAI,24-hour urine protein,urea,creatinine,uric acid and the incidence of renal damage were significantly elevated in moderate-severe anemia group(both P<0.05).And SLEDAI and uric acid increased significantly in mild anemia group(both P<0.05).As compared with SLE mild anemia group,SLEDAI,24-hour urine protein,urea,creatinine and the incidence of renal damage rose markedly in moderate-severe anemia group(both P<0.05).As compared with SLE renal normal anemia subgroup,Hb declined obviously while SLEDAI,24-hour urine protein and uric acid spiked markedly in renal insufficiency anemia subgroup.Hb of SLE patients was correlated positively with C3/C4(both P<0.05)and negatively with C-reactive protein(CRP),24-hour urine protein,urea,creatinine,uric acid and SLEDAI(both P<0.05).Multivariate Logistic regression indicated that anemia was independently associated with SLE disease activity and renal damage.According to ROC curve,area under curve of Hb for predicting the disease activity and renal damage in SLE patients were 0.768 and 0.716 respectively.At the most optimal cut-off values of 106.5 and 102.5 g/L,the sensitivity was 72.62% and 74.75% and the specificity 71.85% and 64.77% respectively.Conclusions Hemoglobin may be a potential inflammatory marker for evaluating disease activity and renal damage in SLE patients.And varying severity of anemia may reflect different degrees of disease activity and renal damage.