Prevalence of anemia according to stage of chronic kidney disease in a large screening cohort of Japanese.

Background: The prevalence of chronic kidney disease (CKD) is high in developed countries, including Japan. However, little is known about the prevalence of anemia according to the estimated glomerular filtration rate (eGFR) among Japanese.

Methods: We studied screenees on the Okinawa General Health Maintenance Association (OGHMA) registry in 1993 (N = 94,602; 54,848 women and 39,754 men) who had both serum creatinine and hematocrit data. Anemia was defined as follows: hematocrit level <40% in men, <32% in women aged <50 years, and <35% in women aged >or=50 years. GFR was estimated using a new Japanese equation: eGFR (ml/min per 1.73 m(2)) = 194 x serum creatinine(1.094) x age(0.287) x 0.739 (if female).

Results: The prevalence of anemia clearly increased as CKD progressed below an eGFR of 60 ml/min per 1.73 m(2) in both genders. Logistic analysis adjusted with body mass index and older age (>or=70 years) revealed that the odds ratio for complications of anemia was significantly increased below an eGFR of 45 ml/min per 1.73 m(2) in women and 90 ml/min per 1.73 m(2) in men. The association of lower kidney function with anemia was found to be more prevalent: adjusted odds ratio >or=2.0, from approximately 50 ml/min per 1.73 m(2).

Conclusion: The present study suggested that there might be as many as 1,000,000 people with CKD stage 3-5 complicated with anemia in Japan.