SALT LAKE CITY—Is abnormal iron balance associated with increased mortality in predialysis patients with chronic kidney disease?

A study in Kidney International suggested that the answer is not clear, because parameters have not been well characterized.

To remedy that, VA Salt Lake City Health Care System-led researchers performed a historical cohort study using data from the VA Corporate Data Warehouse to evaluate the relationship between iron status and mortality.

Researchers identified a predialysis CKD cohort with at least one set of iron indices between 2006 and 2015. The cohort was divided into four iron groups based on the joint quartiles of serum transferrin saturation (percent) and ferritin concentration (ng/ml):

  • reference (16-28%, 55-205 ng/ml),
  • low iron (0.4-16%, 0.4-55 ng/ml),
  • high iron (28-99.6%, 205-4941 ng/ml), and
  • function iron deficiency (0.8-16%, 109-2783 ng/ml).

Mortality risk between the iron groups was compared using matching weights based on multinomial propensity score models and Poisson rate-based regression. The study team also evaluated if the association between iron groups and mortality differs between the diabetic and nondiabetic subgroups.

Of 80,067 eligible veterans, 32,489 were successfully matched, according to the study, which reported that, during the mean follow-up period of 4.0 years, adjusted relative rate (95% confidence interval) for all-cause mortality in three abnormal iron groups were increased compared to the reference: functional iron deficiency [1.21 (1.17, 1.25)], low iron [1.10 (1.07, 1.14)] and high iron [1.09 (1.06, 1.13)].

“The mortality risk was similar between diabetic and non-diabetic subgroups for each iron group,” the authors wrote. “Thus, an abnormal iron balance, particularly functional iron deficiency, is associated with increased mortality in CKD.”

1.    Cho ME, Hansen JL, Peters CB, Cheung AK, Greene T, Sauer BC. An increasedmortality risk is associated with abnormal iron status in diabetic andnon-diabetic Veterans with predialysis chronic kidney disease. Kidney Int. 2019Sep;96(3):750-760. doi: 10.1016/j.kint.2019.04.029. Epub 2019 May 15. PubMed PMID: 31345582.