Kidney Week

Abstract: FR-PO519

Iron Status and Mortality Risk in Diabetic and Non-Diabetic 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 mortality risk associated with abnormal iron balance has not been compared between diabetic and non-diabetic CKD populations.

Methods

We performed a historical cohort study using 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. Matching weights were used to determine the effects of FID, HI, and LI on all-cause mortality, 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 covariates were evenly distributed among the iron groups. During the mean±SD follow-up period of 4.0±2.7 years, FID exhibited the greatest risk for all-cause mortality [Risk Ratio, RR (95% CI): 1.21 (1.17, 1.25)], after being stratified by the diabetes status and matching for age, sex, race, BMI, dyslipidemia, eGFR, albumin, hemoglobin, eGFR, and CV history. The RRs for mortality with HI and LI were similarly increased, 1.09 (1.06, 1.13). The association between iron status and mortality risk was not modified by the diabetes status.

Conclusion

Abnormal iron status, particularly FID, is associated with increased all-cause mortality risk in pre-dialysis CKD, regardless of the diabetes status. Further studies are needed to investigate the underlying mechanism.

Funding

• Veterans Affairs Support