Hematocrit may predict mortality, study finds

Hematocrit measurements can predict long-term mortality in patients with hypertension, a recent study found.

The cohort study included more than 10,000 Scottish patients who were seen at a hypertension clinic. Hematocrit was measured at their initial clinic visits and at follow-up visits for up to 35 years. Overall, men had higher median hematocrit than women (0.44 vs. 0.41). The lowest mortality risk was seen in men with a hematocrit between 0.421 and 0.440 and in women between 0.381 and 0.400. In general, the researchers concluded that a hematocrit above 0.44 was associated with increased risk of death for hypertensive men or women.

The sexes differed in the pattern and causes of mortality, however. In general, men had an increased risk of death with hematocrit below 0.42, with a J-shaped pattern for cardiovascular mortality, but their risk for non-cardiovascular mortality had a linear relationship with hematocrit. Women had a lower threshold at which their mortality risk was increased (0.38) and a U-shaped pattern for non-cardiovascular mortality.

The study also found that patients with higher hematocrit at baseline had higher blood pressure on treatment, but that higher hematocrit was associated with increased mortality risk whether or not patients achieved blood pressure targets. Given the limitations of the data, researchers weren't able to determine whether more aggressive blood pressure management would lower the mortality risk of patients with high hematocrit.

Still, they concluded that hypertensive patients with hematocrit levels in the higher risk ranges should be targeted for aggressive blood pressure management and other cardiovascular risk reduction. Hematocrit levels should be considered an important risk predictor in these patients, the authors said. They called for additional research to assess the differing relationships between hematocrit and mortality in men and women, and to develop management strategies for high hematocrit levels. The study was published online July 16 by Hypertension.