Hematocrit Level and Associated Mortality in Hemodialysis Patients

TLDR

Higher hematocrits have been linked to better cognitive function, less left ventricular hypertrophy, greater exercise tolerance, and improved quality of life, but the optimal survival‑associated level remains unknown. The study retrospectively examined how hematocrit levels relate to mortality in a national Medicare hemodialysis cohort. Hematocrit was measured during a six‑month entry period (July–December 1993) and patients were followed through December 1994, with comorbidities and disease severity extracted from Medicare claims and linked to entry hematocrit levels. Patients with hematocrit below 30 % had a 12–33 % higher all‑cause mortality risk, whereas those with 33–36 % had the lowest risk, and after adjusting for disease severity the 33–36 % group still showed a 4 % mortality reduction, indicating that sustained hematocrit increases improve survival. Abstract.

Abstract

Abstract. Although a number of clinical studies have shown that increased hematocrits are associated with improved outcomes in terms of cognitive function, reduced left ventricular hypertrophy, increased exercise tolerance, and improved quality of life, the optimal hematocrit level associated with survival has yet to be determined. The association between hematocrit levels and patient mortality was retrospectively studied in a prevalent Medicare hemodialysis cohort on a national scale. All patients survived a 6-mo entry period during which their hematocrit levels were assessed, from July 1 through December 31, 1993, with follow-up from January 1 through December 31, 1994. Patient comorbid conditions relative to clinical events and severity of disease were determined from Medicare claims data and correlated with the entry period hematocrit level. After adjusting for medical diseases, our results showed that patients with hematocrit levels less than 30% had significantly higher risk of all-cause (12 to 33%) and cause-specific death, compared to patients with hematocrits in the 30% to less than 33% range. Without severity of disease adjustment, patients with hematocrit levels of 33% to less than 36% appear to have the lowest risk for all-cause and cardiac mortality. After adjusting for severity of disease, the impact of hematocrit levels of 33% to less than 36% is vulnerable to the patient sample size but also demonstrates a further 4% reduced risk of death. Overall, these findings suggest that sustained increases in hematocrit levels are associated with improved patient survival.