The association of the difference in hemoglobin levels before and after hemodialysis with the risk of 1-year mortality in patients undergoing hemodialysis. Results from a nationwide cohort study of the Japanese Renal Data Registry.

BACKGROUND: Few clinical studies have directly examined the associations of hemoglobin (Hb) levels after hemodialysis (HD) and of the difference in Hb levels before and after HD (ΔHb) with patient outcomes. The present study aimed to determine ΔHb and post-HD Hb levels with nationwide data and to examine their associations with all-cause mortality in patients undergoing HD.

METHODS: This study is based on data from 2008 and 2009 recorded in the Japanese Renal Data Registry. Study endpoints were all-cause mortality within 1-year. The ΔHb and post-HD Hb level as categorical variables using Cox regression for 1-year mortality, adjusting for potential confounders.

RESULTS: The median ΔHb was 1.0 g/dl, and the post-HD Hb level was 11.3 g/d. The median pre-HD Hb level was 10.4 g/dl. The risk of mortality was lower with a ΔHb of 0 to 1.0 g/dl (adjusted hazard ratio [aHR], 0.90; 95% confidence interval [CI], 0.70-1.01) or > 1.0 g/dl (aHR, 0.73; 95% CI, 0.64-0.84) than with a ΔHb < 0 g/dl. The risk for mortality was also lower with a post-HD Hb of 10 to 11 g/dl (aHR, 0.82; 95% CI, 0.73-0.92), 11 to 12 g/dl (aHR, 0.77; 95% CI, 0.68-0.87), or > 12 g/dl (aHR, 0.77; 95% CI, 0.68-0.87) than with a post-HD Hb < 10 g/dl.

CONCLUSIONS: Both a low ΔHb and a low post-HD Hb level were associated with a higher risk of 1-year mortality.