Sex Differences in Association of Hemoglobin with Survival

In women without kidney disease, lower hemoglobin levels are common. However, according to Norio Hanafusa, MD, PhD, and colleagues, there are few data available on the sex-specific management of anemia in patients on hemodialysis.

The researchers conducted a study designed to examine the role of sex differences in the association between categorical baseline or time-varying hemoglobin levels and all-cause mortality. Results were reported online in Nephrology [doi.org/10.1111.nep.14046].

The prospective cohort study utilized data from 6890 patients in J-DOPPS (Japan Dialysis Outcomes and Practice Patterns Study), 2005-2015. Cox regression and likelihood ratio tests were used to examine the associations of interest and the effect modification of sex on the relationship between hemoglobin and mortality.

During a median follow-up of 31 months, 781 patients died. Following adjustment for case mix, there was variation in mortality risk between five hemoglobin categories. The highest hemoglobin category (≥12 g/dL) had a hazard ratio of 0.73 (95% confidence interval [CI], 0.41-1.29) for women and 2.02 (95% CI, 1.03-3.95) for men, compared with hemoglobin category 10 to 10.9 g/dL.

Despite the difference, the P-value comparing the overall hazard ratio among men versus women was .35. In models stratified by patient age (<75 years), time of dialysis (≤1 year), and models lagging the hemoglobin exposure, similar associations were observed.

In conclusion, the researchers said, “The results based on this sample of Japanese hemodialysis patients did not support the hypothesis that the association between hemoglobin and survival differed by sex. We also could not conclude that the association was identical, as the parameter estimates are consistent with male patients having a relatively greater mortality risk than female patients at higher hemoglobin levels. More detailed investigations into the effects of higher hemoglobin levels by sex might help better understand strategies for anemia management.”