Objective Chronic kidney disease (CKD) is an important worldwide health problem. The incidence of end-stage renal disease (ESRD) is increasing steadily around the world, however few studies have discussed the risk factors for progression in patients with early-stage CKD. Therefore, we designed a retrospective cohort study of patients with early-stage CKD to identify the risk factors influencing the annualized slope of the estimated glomerular filtration rate (eGFR).
Methods and Patients In this longitudinal cohort study, baseline examination was conducted in 2012 outpatients treated at the Kidney Center, Tokyo Women's Medical University. Follow-up examinations were completed in 485 patients with stage 1 and stage 2 CKD within the study period (2002-2007). The conventional risk factors for CKD progression, such as proteinuria, blood pressure, serum triglyceride, serum HDL, fasting plasma glucose, smoking habit, hypertension or treatment with antihypertensive medication and body mass index, were examined. The annualized eGFR slope was calculated at the start and end of the study period. Multivariate analysis was performed to determine the associations of the eGFR slope with the predisposing risk factors.
Results The mean annualized eGFR slope was -1.64 mL/min/1.73 m²/year. Concerning the relationship between etiology and the GFR decreasing slope, IgA nephropathy was defined as the worst (-1.80 mL/min/year) due to the high ratio of proteinuria. Proteinuria (-2.13 mL/min/1.73 m²/year, p=0.005), smoking habit (-2.06 mL/min/1.73 m²/year, p=0.014), low serum HDL (-1.95 mL/min/1.73 m²/year, p=0.035), and hypertension (-1.73 mL/min/1.73 m²/year, p=0.045) were all significantly related to the eGFR slope. The estimated GFR for the highest BMI quartile was significantly higher than that of the eGFR for the lowest BMI.
Conclusion Proteinuria, smoking habit, hypertension and low HDL were clearly related to accelerated disease progression in patients with early-stage CKD. Therefore, aggressive treatment of these risk factors is essential in the early stages of CKD.