To analyze the distribution levels of complete blood count parameters of apparently healthy elderly population in China, and explore the correlation between blood count parameters and age based on data derived from 7 613 participants.

A total of 7 613 apparent healthy elderly people aged over 60 years were recruited from 10 clinical centers across China between April to July 2018. There were 3 808 participants aged between 60 and 69 years, 2 222 aged between 70 and 79 years, and 1 133 aged ≥80 years. Blood routine examination was performed using automated complete blood analyzer of Sysmex company and blood smear microscopic examination were conducted by experienced clinical laboratory technician. Rank sum test, one-way ANOVA and t test were used to compare the results of different age groups (60-69, 70-79, ≥80 years) and the differences between genders. The 2.5 percentiles and 97.5 percentiles of each parameter were taken as the distribution levels of the population.

(1) Red blood cell count (RBC), hemoglobin (Hb), hematocrit (Hct) reduced and mean corpuscular volume (MCV) increased with increasing age (P<0.05). The count of red blood cells and hemoglobin levels decreased slightly in women than men (P<0.05). The proportion of anemia in men is higher than in women in all age groups (1.47% (31/2 102) vs 1.00% (17/1 706) in 60-69 years old, 2.18% (30/1 376) vs 1.65% (14/846) in 70-79 years, 7.06% (55/779) vs 6.21% (22/354) in age ≥80 years group; χ²=108.074,P<0.001). (2) The white blood cell count was similar among various age groups. Neutrophil and monocyte percentage increased (P<0.05), and lymphocytes decreased with increasing age (P<0.05). (3) Platelets count (PLT) decreased with aging (P<0.01). There is a certain difference in the distribution level of common items such as RBC, Hb, Hct, MCV, neutrophil percentage, lymphocyte percentage, monocyte percentage, and PLT count between elderly apparent healthy people (over 60 years) and the reference interval for blood cell analysis of Chinese adults issued by national industry standards.

There are some differences between the distribution levels of apparent elderly healthy people (over 60 years) and the reference intervals commonly used in our country. More attentions should be paid to these differences in the diagnosis and treatment of disease and chronic disease management. Further studies are needed to determine the reference intervals of healthy elderly population in China, which would be helpful to clinical diagnosis and treatment in this population.

Blood cells; Aged; Multicenter study