Predictors of anemia in a multi-ethnic chronic kidney disease population: a case-control study

Anemia is a common complication of chronic kidney disease (CKD). However, risk factors of anemia in CKD patients in Singapore are not well established. Hence, a retrospective, case-control study involving non-dialysis CKD patients was conducted to determine possible predictors of anemia in the local CKD population. Non-dialysis adult CKD patients, not receiving renal replacement therapy or erythropoiesis-stimulating-agents were included. Parameters collected included demographics e.g. age, sex and race; clinical data e.g. CKD stage and medical/medication histories; and laboratory data e.g. serum electrolytes, urinary and hematologic parameters. Patients were classified as anemic or non-anemic using a threshold hemoglobin level of 10 g/dL. The parameters were evaluated for their predictive value for anemia development using multivariate logistical regression and calculation of odds ratios. Statistical analyses were performed using STATA. A total of 457 patients (162 anemic and 295 non-anemic) were analysed. Multivariate analysis showed that probability of developing anemia was greater for patients with stage 5 CKD (OR 16.76, p < 0.001), with hematological disorders (OR 18.61, p < 0.001) and with respiratory disorders (OR 4.54, p = 0.004). The probability of developing anemia was lower for patients with higher previous hemoglobin concentration (OR 0.32, p < 0.001) and in those receiving iron supplements (OR 0.44, p = 0.031). Gender and race were not found to be significant predictors of anemia. Risk of anemia is increased in patients with advanced CKD, haematological disorders, respiratory disorders, and those not taking iron supplements. This study has increased our understanding of the patient subgroups at risk for anemia.