Background: Patients with renal impairment are at risk of not only end-stage kidney disease but also cardiovascular disease (CVD). The current definition of CKD stage G3a is eGFR 45-59 ml/min/1.73 m2 and of G3b is 30-44 ml/min/1.73 m2, and subjects in the CKD 3a category are considered to be at lower risk of mortality than are those in CKD 3b.
Methods: We evaluated the outcome of 97,043 people (33,131 men and 63,912 women) living in Ibaraki Prefecture who underwent annual community-based health checkups beginning in 1993 at age 40-80 years and who were followed for a mean of 17.1 years.
Results: The number of all-causes deaths was 20,534 (10,375 men and 10,159 women), of which 5,995 (2,695 men and 3,300 women) were deaths due to CVD. Multivariable-adjusted hazard ratio for CVD death in the eGFR 45-49 ml/min/1.73 m2 category was significantly increased (1.82; 95% confidential interval, 1.23-2.69) in non-elderly men, whereas all-cause mortality and CVD mortality in elderly men with eGFR 45-49 ml/min/1.73m2 were non significant. In contrast, both in non-elderly women and in elderly women with eGFR 45-49 ml/min/1.73 m2 showed small, but significant, increases in the risks of all-cause mortality and CVD.
Conclusions: We demonstrated proportionate increases in mortality with decreasing eGFR in a Japanese CKD population. Like patients in the CKD G3b subgroup, non-elderly men and women with an eGFR of 45-49 ml/min/1.73 m2 (i.e. a part of CKD G3a) are at considerable risk of CVD mortality. Age dependent and eGFR dependent finer risk recognition were required for CVD prevention in clinical practice with regard to CKD patients.