Clinical and economic outcomes in Medicare beneficiaries with stage 3 or stage 4 chronic kidney disease and anemia: the role of intravenous iron therapy.

Abstract

Anemia in patients with chronic kidney disease (CKD) is associated with increased morbidity and mortality, decreased quality of life, and substantial health care costs. Iron therapy is recommended, usually in combination with an erythropoiesis-stimulating agent (ESA), in many CKD patients with anemia and low iron levels to raise hemoglobin levels to a range of 10 to 12 grams per deciliter; iron deficiency is defined by a ferritin score less than 100 micrograms (mcg) per liter and transferrin saturation (TSAT) less than 20%. To examine the use of intravenous (IV) iron and its associated economic and clinical outcomes in Medicare beneficiaries with stage 3 or stage 4 CKD and anemia. This was a retrospective cohort analysis using 2006 and 2007 Medicare 5% Standard Analytic Files (SAF). Use of therapy with IV iron and/or ESAs was identified among patients diagnosed with CKD and anemia. The study index quarter was the first quarter in 2006 during which the patient had primary or secondary diagnoses of both CKD and anemia. Based on the receipt of IV iron or ESA treatment in the index quarter, patients were classified into 1 of 4 treatment groups: IV iron and ESA; IV iron without ESA; ESA without IV iron; neither IV iron nor ESA. Therapy with oral iron was not measurable with this database. Clinical and economic outcomes, including the progression to advanced CKD stages, development of anemia, mortality, hospitalization, and net Medicare reimbursement (i.e., not including patient or supplemental plan contribution) for all-cause health care services, were examined for 1 year following the index quarter. Between-group differences were tested using Pearson chi-square for categorical variables and the Kruskal-Wallis nonparametric test for reimbursement. Multivariate logistic regression models were estimated to assess the associations of mortality, inpatient hospitalization, skilled nursing facility (SNF) admission, and hospice care with treatment regimen, controlling for patient demographic and clinical characteristics. Of the 4,310 study patients with both CKD and anemia, 2,913 (67.6%) received neither IV iron nor ESA; 984 (22.8%) received ESA without IV iron; 277 (6.4%) received IV iron and ESA; and 136 (3.2%) received IV iron without ESA in the index quarter. Logistic regression analyses showed that patients receiving neither IV iron nor ESA (reference group) were at increased risk of death compared with patients receiving both IV iron and ESA (OR = 0.62, 95% CI = 0.42-0.90). Additionally, patients receiving neither IV iron nor ESA were more likely to be hospitalized compared with patients receiving both IV iron and ESA (OR = 0.66, 95% CI = 0.50-0.87), IV iron without ESA (OR = 0.55, 95% CI = 0.38-0.79), and ESA without IV iron (OR = 0.73, 95% CI = 0.62-0.87). Further, patients not receiving IV iron or ESA were more likely to be admitted to an SNF than patients receiving both IV iron and ESA (OR = 0.44, 95% CI = 0.32-0.61), IV iron without ESA (OR = 0.57, 95% CI = 0.36-0.88), and ESA without IV iron (OR = 0.56, 95% CI = 0.47-0.67). Patients receiving neither IV iron nor ESA in the index quarter had the highest mean [SD] total Medicare reimbursement per patient in the subsequent year ($42,353 [$52,887]) compared with patients receiving IV iron without ESA ($28,654 [$32,068]), IV iron and ESA ($34,152 [$30,506]), or ESA without IV iron ($38,172 [$35,591], P = 0.001). Use rates of IV iron and ESA in a sample of Medicare enrollees with CKD and anemia in 2006 suggest that anemia management therapies may be underutilized; however, oral iron therapy use was not measurable with the study database, and therapies initiated after the index quarter were not measured. Patients not treated with IV iron or ESA had significantly higher rates of hospitalization and SNF admission than patients treated with either IV iron or ESA. Further, mortality was significantly higher in patients receiving neither IV iron nor ESA than in patients who received IV iron and ESA. Additionally, total all-cause health care costs were higher among patients receiving neither IV iron nor ESA treatment compared with patients treated with IV iron and/or ESA.