An evaluation of stage-based survival and renal prognosis in the general super-older population of Japan.

BACKGROUND

The risk of mortality and cardiovascular disease (CVD) may be higher among some super-older adults with chronic kidney disease (CKD). We assessed outcomes across CKD stages in an aging Japanese population.

METHODS

This retrospective cohort study using nationwide health examination and insurance claims database enrolled individuals aged 75-90 years whose renal function was measured > 2 times during the observation period. CKD stages were classified using eGFR and urinary protein levels. We used a Cox proportional hazards model to evaluate all-cause mortality and CVD events by CKD stage and a logistic regression model to assess dialysis initiation by renal function and proteinuria among patients with advanced CKD.

RESULTS

Of 365,664 individuals aged 75-90 years, > 30% met the CKD diagnosis criteria, mostly the CKD G3aA1 category. During follow-up, 18,238 deaths and 48,937 CVD events occurred. Mortality and CVD incidence increased with advancing CKD stages. Mortality risk was elevated only among G3a patients with urinary protein (A2/3: HR 1.64 [95% CI 1.53-1.76]), but not without (A1: HR 1.01 [0.97-1.05]). CVD risk increased significantly across all A2/3 stages, but not in A1. Dialysis was initiated in 9.5% of patients with CKD G4/5, with an earlier risk observed in the A2/3 group.

CONCLUSION

In older adults, CKD prognosis varies according to stage and proteinuria. Most individuals with early-stage, proteinuria-negative CKD do not experience adverse outcomes, whereas trace or greater proteinuria indicates higher risk. Outcome-based CKD management in a super-older population is essential to avoid overtreatment and ensure appropriate care.