title: Haemoglobin concentration and the risk of death in older adults: differences by race/ethnicity in the NHANES III follow-up.
abstract: Mildly low haemoglobin concentration is associated with increased mortality in older adults. However, this relationship has not been well characterized in racial/ethnic minorities. Therefore, this study determined the haemoglobin threshold below which risk of death is significantly increased in older non-Hispanic whites, non-Hispanic blacks, and Mexican Americans. Data on 4089 participants of the 1988-94 US National Health and Nutrition Examination Survey who were > or =65 years of age were analyzed with mortality follow-up through December 31, 2000. Mean haemoglobin in non-Hispanic whites (n = 2686) and Mexican Americans (n = 663) was 140 g/l, while in non-Hispanic blacks (n = 740) the mean was 10 g/l lower. A total of 1944 (47.5%) participants died. Among non-Hispanic whites and Mexican Americans, age- and sex-adjusted models showed that the haemoglobin thresholds below which mortality risk was significantly increased were 4 and 2 g/l respectively, above the World Health Organization (WHO) cut-off points for anaemia. In contrast, the threshold for non-Hispanic blacks was 7 g/l below the WHO criteria. Similar threshold effects were observed when analyzing haemoglobin in categories and adjusting for multiple confounders. In conclusion, the haemoglobin threshold below which mortality rises significantly is a full g/dl lower in non-Hispanic blacks than in non-Hispanic whites and Mexican Americans.
authors.affiliation: Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, NIH, Bethesda, MD 20892-9205, USA. patelku@mail.nih.gov
authors.forename: Kushang V
authors.initials: KV
authors.lastname: Patel
authors.forename: Dan L
authors.initials: DL
authors.lastname: Longo
authors.forename: William B
authors.initials: WB
authors.lastname: Ershler
authors.forename: Binbing
authors.initials: B
authors.lastname: Yu
authors.forename: Richard D
authors.initials: RD
authors.lastname: Semba
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.forename: Jack M
authors.initials: JM
authors.lastname: Guralnik