Kidney Week

Abstract: FR-PO520

Iron Status and the Risk of Incident ESRD in Veterans with CKD

Session Information

• CKD: Epidemiology, Outcomes - Non-Cardiovascular - I
  November 03, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Chronic Kidney Disease (Non-Dialysis)

• 304 CKD: Epidemiology, Outcomes - Non-Cardiovascular

Authors

• Cho, Monique E., Veterans Health Administration, Salt Lake City, Utah, United States

Monique E. Cho,

• Hansen, Jared, Veterans Health Administration, Salt Lake City, Utah, United States

Jared Hansen,

• Peters, Celena B., Veterans Health Administration, Salt Lake City, Utah, United States

Celena B. Peters,

• Sauer, Brian C., Veterans Health Administration, Salt Lake City, Utah, United States

Brian C. Sauer,

Background

The risk for CKD progression associated with abnormal iron balance has not been evaluated in a large CKD population.

Methods

We performed a historical cohort study using the national data from the Veterans Affairs Informatics and Computing Infrastructure. We identified a pre-dialysis CKD cohort (MDRD eGFR <60 mL/min/1.73m²) with at least one set of iron indices between 2006-2015. The clinical characteristics were determined from the ICD-9 codes and laboratory data during the baseline period, defined as the year preceding the first available iron indices. Patients with ESRD, genetic, and chronic disorders affecting iron metabolism were excluded. The cohort was divided into 4 iron groups based on the joint quartiles (Q) of transferrin saturation (Tsat) and ferritin: functional iron deficiency (FID), 1^st Tsat Q + 3^rd−4^th ferritin Qs; Low Iron (LI), 1^st Tsat+ferritin Qs; High Iron (HI), 4^th Tsat+ferritin Qs; and Reference (R), 2^nd−3^rd Tsat+ferritin Qs. Incident ESRD was determined by the diagnosis and procedure codes reflecting renal transplantation or dialysis. Matching weights were used to determine the effects of FID, HI, and LI on incident ESRD, using R as the reference. Diabetes was examined as a potential effect modifier.

Results

Of the 1,159,371 Veterans with CKD, 148,611 met the inclusion criteria. The mean±SD for age and eGFR were 72±11 years and 43±11 mL/min/1.73 m², respectively. The median (IQR) Tsat and ferritin values were 20 (14, 26)% and 119 (64, 196) ng/mL. Of the study cohort, 42% could not be categorized into any of the 4 iron groups. In the remaining 83,439 Veterans, the prevalence for FID, HI, LI, and R were 13%, 17%, 20%, and 50%, respectively. After matching weights were implemented, the clinical covariates were evenly distributed among the iron groups. During the mean±SD follow-up period of 4.0±2.7 years, only HI exhibited increased risk for ESRD, [risk ratio, RR (95% CI): 1.16 (1.10, 1.23)]. The RRs for FID and LI were 0.97 (0.91, 1.03) and 0.78 (0.73, 0.83), respectively. The association between iron status and ESRD risk was not altered by the diabetes status.

Conclusion

High iron status is associated with increased risk for incident ESRD in CKD, while iron deficiency is associated with reduced risk for ESRD. Diabetes was not found to be an effect modifier. Further studies are required to confirm the finding and to investigate the underlying mechanisms.

Funding

• Veterans Affairs Support