Abstract

Introduction: This study examined the association between hemoglobin (Hb) levels and all-cause mortality in community-dwelling individuals in Japan.

Methods: Participants were 1,243 males (62 ± 14 years old) and 1,754 females (64 ± 12 years old). The research was based on a follow-up study with 7- and 19-year intervals.

Results: The follow-up survey revealed 448 male deaths (36.0% of male participants) and 419 female deaths (23.9% of female participants). Male  participants' hazard ratio (HR) for all-cause mortality was significantly higher for groups whose Hb level was < 11.0 g/dL (HR: 2.39; 95% confidence interval [CI]: 1.28-4.47) or in the range 11.0-11.9 g/dL (2.11; 1.23-3.62) or 12.0-12.9 g/dL (1.66; 1.15-2.41) than for the reference group (14.0-14.9 g/dL). For female participants, the HR for all-cause mortalitywas significantly higher in groups whose Hb level was < 11.0 g/dL (1.91; 1.19-3.05), in the range 11.0-11.9 g/dL (1.44; 1.03-2.03), or ≥ 15.0 g/dL (1.77; 1.10-2.85) than for the reference group (13.0-13.9 g/dL).

Conclusions: The study revealed a linear positive association between Hb levels and the risk of all-cause mortality for male participants. However, this association formed a J-shaped curve for female participants.