Does stage III chronic kidney disease always progress to end-stage renal disease? A ten-year follow-up study

Objective. Clinically, it may be appropriate to subdivide patients with stage 3 chronic kidney disease (CKD) into two subgroups, as they show different risks for kidney outcomes. This study evaluated the proportion of patients with stage 3 CKD who progressed to stage 4 or 5 CKD over 10 years and independent predictors of progression of renal dysfunction. It sought to validate whether stage 3 CKD patients should be subdivided. Material and methods. This retrospective cohort study enrolled 347 stage 3 CKD patients between January 1997 and December 1999, who were followed up through June 2010. The baseline clinical characteristics and outcomes were compared in patients with stage 3A [45 <estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2)] and stage 3B (30 < eGFR < 45 ml/min/1.73 m(2)) CKD. Results. Of the 347 patients, 196 (58.2%) were in stage 3A. The only difference in baseline characteristics between stages 3A and 3B patients was the degree of albuminuria. During follow-up, 167 patients (48.1%) did not progress, 60 (17.3%) progressed to stage 4 and 120 (34.6%) progressed to stage 5, with 91 (26.2%) starting dialysis. Multivariate Cox regression analysis showed that macroalbuminuria [(hazard ratio (HR) 3.06, 95% confidence interval (CI) 1.48-2.89, p < 0.001], microalbuminuria (HR 1.99 95% CI 1.04-3.85, p = 0.038), microscopic haematuria (HR 2.07 95% CI 1.48-2.89, p < 0.001) and stage 3B CKD (HR 2.99 95% CI 2.19-4.10, p < 0.001) were independent predictors of progression of renal dysfunction. Stage 3B patients had higher risks of adverse renal and cardiovascular outcomes than stage 3A patients. Conclusions. About half of the patients with stage 3 CKD progressed to stage 4 or 5, as assessed by eGFR, over 10 years. Degree of albuminuria, stage 3 subgroup and microscopic haematuria were important risk factors for progression of stage 3 CKD. It would be appropriate to divide the present stage 3 CKD into two subgroups.