Usefulness of the blood hematocrit level to predict development of heart failure in a community.

Current data suggest that increases in hemoglobin may decrease nitric oxide and adversely affect vascular function. In the preclinical setting, these changes could precipitate the development of heart failure (HF). We hypothesized that higher hematocrit (HCT) would be associated with an increased incidence of new-onset HF in the community. We evaluated 3,523 participants (59% women) from the Framingham Heart Study who were 50 to 65 years old and free of HF. Participants were followed prospectively until an HF event, death, or the end of 20 years of follow up. HCT was subdivided into 4 gender-specific categories (women: HCT 36.0 to 40.0, 40.1 to 42.0, 42.1 to 45.0, >45.0; men: 39.0 to 44.0, 44.1 to 45.0, 45.1 to 49.0, >49.0). Gender-pooled multivariable Cox proportional hazards models were used to estimate the association of HCT with incident HF, adjusting for clinical risk factors. During the follow-up period (61,417 person-years), 217 participants developed HF (100 events in women). There was a linear increase in risk of HF across the 4 HCT categories (p for trend = 0.002). Hazards ratios for HF in the low-normal, normal, and high HCT categories were 1.27 (95% confidence interval 0.82 to 1.97), 1.47 (1.01 to 2.15), and 1.78 (1.15 to 2.75), respectively, compared to the lowest HCT category (p for trend <0.0001). Adjustment for interim development of other cardiovascular diseases and restriction of the sample to nonsmokers did not alter the results. In conclusion, higher levels of HCT, even within the normal range, were associated with an increased risk of developing HF in this long-term follow-up study.