Effects of age on polycythemia, cardiometabolic risk and their associations in middle-aged men.

Background: Polycythemia has been reported to be associated with cardiometabolic risk factors. However, it remains to be determined whether age affects their associations. Methods: The subjects were 11,261 men at ages of 30 ~ 65 years who had received annual health checkup examinations. They were divided by age into four groups of 30 ~ 39, 40 ~ 49, 50 ~ 59 and 60 ~ 65 years. Variables related to polycythemia and cardiometabolic risk and their associations were compared in the different age groups. Results: The prevalences of polycythemia and metabolic syndrome tended to be lower and higher, respectively, with an increase of age. Odds ratios (ORs) of subjects with vs. subjects without polycythemia for high LDL-C/HDL-C ratio and metabolic syndrome were significantly high in the age group of 30 ~ 39 years when compared with the reference level (OR with 95% confidence interval: 3.21 [2.35 ~ 4.37] [high LDL-C/HDL-C ratio] and 3.49 [2.38 ~ 5.12] [metabolic syndrome]) and tended to be lower with an increase of age (60 ~ 65 years, OR with 95% confidence interval: 1.36 [0.63 ~ 2.93] [high LDL-C/HDL-C ratio] and 1.88 [1.16 ~ 3.03] [metabolic syndrome]). Conclusion: The prevalence of polycythemia was higher and its associations with cardiometabolic risk such as high LDL-C/HDL-C ratio and metabolic syndrome were stronger in the youngest group than in the older groups. The results suggest that early detection and correction of polycythemia are more effective than its later correction for prevention of cardiovascular disease in middle-aged men.