Anemia is a common complication of chronic kidney disease (CKD), and is largely due to a decrease in erythropoietin production. In both pediatric and adult cases of CKD, anemia is associated with an increased risk of hospitalization and mortality. Several large observational studies in adults have shown that irrespective of dialysis status, CKD patients have lower mortality and morbidity when higher hemoglobin (Hb) levels are achieved. However, the results of randomized, controlled interventional trials in these populations suggest that targeting higher Hb levels may be associated with an increased risk of adverse outcomes. Little is known about the relationship between achieved Hb levels and outcomes in pediatric patients with CKD. Thus, a recent study by Staples et al assessed the prevalence of anemia in children with predialysis CKD, and described the association between anemia and morbidity (hospitalization).

The retrospective cohort study included 2,779 patients (aged 2-20 years) with CKD that were enrolled in the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS). Patients were categorized by disease severity into one of five stages (I-V) of CKD based on glomerular filtration rate; anemia was defined by a hematocrit <33%. The study’s primary outcome was hospitalization during the 1-year follow-up period after enrollment.

Overall, the prevalence of anemia increased from 18.5% in CKD stage II to 68% in CKD stage V, and more anemic patients were hospitalized than nonanemic patients. After adjusting for a variety of factors such as erythropoietin use, race, height, and albumin, statistical analysis revealed that anemic patients were 55% more likely to be hospitalized than were nonanemic patients. Finally, patients with a hematocrit above 36% did not have an increased rate of hospitalization, nor did patients who underwent a complete correction of anemia.

The results of this study underline important issues regarding the potential care of pediatric CKD patients who are not on dialysis. However, the NAPRTCS database is a voluntary registry, and thus a significant number of pediatric CKD patients may not be enrolled. Furthermore, many patients were excluded from the study because of missing data or failure to follow-up. These limitations allow focus on only a specific cohort of patients that may not be generalizable to the overall pediatric CKD population. Such studies are clearly hypothesis generating and suggest that future controlled, interventional trials should focus on the effects that correction of anemia has on hospitalization rates, quality of life, and other outcomes in this patient population.

Staples AO, Wong CS, Smith JM, Gipson DS, Filler G, Warady BA, Martz K, Greenbaum LA. Anemia and Risk of Hospitalization in Pediatric Chronic Kidney Disease. Clin J Am Soc Nephrol. 2008 Dec 3.

NAAC Expert Commentary:
Anemia is highly prevalent in adult patients with CKD, but the prevalence and consequences are less well documented in pediatric patients. This is particularly important since nephrologists have effective tools to treat this condition, including erythropoiesis-stimulating agents and oral and parenteral iron. The current study adds significant new information to help us better understand the association of anemia and outcomes in younger patients. It is clear that those children with lower Hb levels have increased morbidity, as measured by hospitalizations. While of considerable interest, this study should be considered hypothesis generating, rather than definitive. As the authors point out, future studies need to be prospective, controlled, and interventional. Additional key outcomes need to be evaluated, such as mortality, and other factors that are unique to this population such as growth and development. The authors should be congratulated for conducting and reporting a rigorous analysis of a growing administrative database, and the renal community should urge support for more rigorous studies in pediatric CKD patients in the future.

Last Updated: January 7, 2009