Excerpt

Anemia is a common complication of chronic kidney disease (CKD), which develops early in the course of CKD and becomes increasingly severe as kidney function deteriorates. Iron deficiency anemia is a continuous process evolving in three stages. The first phase is the depletion of storage iron (stage I), where total body iron is decreased but hemoglobin (Hb) synthesis and red cell indices remain unaffected. Both these indices change when the supply of iron to bone marrow becomes problematic (iron deficient erythropoiesis, or stage II). In stage III the iron supply is insufficient to maintain a normal Hb concentration, and eventually iron deficiency anemia develops.

The management of anemia in CKD patients must strike an appropriate balance between stimulating generation of erythroblasts (erythropoiesis) and maintaining sufficient iron levels for optimum Hb production. It is important to assess iron stores and the availability of iron for erythropoiesis, as adequate iron status is integral to both iron and anemia management in CKD patients. The major cause of iron deficiency is blood loss, particularly for dialysis patients. Dialysis patients are in a state of continuous iron loss from gastrointestinal bleeding (very common), blood drawing, and/or, most importantly, with hemodialysis, the dialysis treatment itself. A CKD patient who receives treatment with erythropoietic-stimulating agents (ESAs) for the anemia often develops iron deficiency, because the iron requirements for achieving a response to ESA treatment usually cannot be met by mobilization of the patient’s iron stores alone. Therefore, supplemental iron therapy, either given orally or intravenously, is often needed among dialysis patients who receive recombinant human erythropoietin (EPO) or darbepoetin alfa treatment. Thus, iron management (iron status assessment and iron treatment) is an essential part of the treatment of anemia associated with CKD, as there are concerns regarding the adverse effects associated with both elevated doses of ESAs and supplemental (intravenous or oral) iron.

Classical iron status tests, of which ferritin and transferring saturation (TSAT) are the most widely used, reflect either the level of iron in tissue stores or the adequacy of iron for erythropoiesis. Though widely used, classical laboratory biomarkers of iron status are not without drawbacks when used in CKD patients: CKD is a pro-inflammatory state, and the biological variability of serum iron, transferrin saturation, and ferritin is known to be large in the context of underlying inflammation. Furthermore, results from a meta-analysis of 55 studies (published before 1990) showed that ferritin radioimmunoassay was the most powerful test (a mean area under the receiver operating characteristic curve of 0.95; 95% CI 0.94, 0.96), compared with mean cell volume determination, TSAT, and red cell volume distribution, for diagnosing adult patients with iron deficiency, but test performances varied between patients with and those without inflammatory (e.g., CKD patients) or liver disease. The accurate assessment of iron status is dependent on the validity and reliability of laboratory test results, and differences in test performance pose a dilemma regarding the most appropriate test to guide treatment decisions.

Contents

• Preface
• Acknowledgments
• Contributors
• Executive Summary
• Background
  • Context
  • Scope of Comparative Effectiveness Review
  • Comparative Effectiveness Review Findings
  • Identification of Evidence Gaps
  • Analytic Framework
• Methods
  • Identification of Evidence Gaps
  • Criteria for Prioritization
  • Engagement of Stakeholders, Researchers, and Funders
  • Research Question Development and Research Design Considerations
• Results
  • Research Needs
• Discussion
  • Challenges
  • Out-of-Scope Future Research Needs Topics
• Conclusions
• References
• Abbreviations
• Appendix A Future Research Needs Process
• Appendix B Effective Health Care Program Selection Criteria
• Appendix C Yield of Ongoing Studies

Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services¹, Contract No. 290-2007-10055-I, Prepared by: Tuft Evidence-based Practice Center, Boston, MA

Suggested citation:

Chung M, Chan JA, Moorthy D, Hadar N, Ratichek SJ, Concannon TW, Lau J. Biomarkers for Assessing and Managing Iron Deficiency Anemia in Late-Stage Chronic Kidney Disease: Future Research Needs. Future Research Needs Paper No. 33. (Prepared by the Tufts Evidence-based Practice Center under Contract No. 290-2007-10055-I.) AHRQ Publication No. 13-EHC038-EF. Rockville, MD: Agency for Healthcare Research and Quality. January 2013. www.effectivehealthcare.ahrq.gov/reports/final.cfm.

This report is based on research conducted by the Tufts Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. 290-2007-10055-I). The findings and conclusions in this document are those of the author(s), who are responsible for its contents; the findings and conclusions do not necessarily represent the views of AHRQ. Therefore, no statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

The information in this report is intended to help health care researchers and funders of research make well-informed decisions in designing and funding research and thereby improve the quality of health care services. This report is not intended to be a substitute for the application of scientific judgment. Anyone who makes decisions concerning the provision of clinical care should consider this report in the same way as any medical research and in conjunction with all other pertinent information, i.e., in the context of available resources and circumstances.

None of the investigators have any affiliation or financial involvement that conflicts with the material presented in this report.

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