Slow progression of chronic kidney disease and what it is associated with.

INTRODUCTION: The risk factors for CKD include diabetes, hypertension, smoking, systemic inflammation, obesity, proteinuria, dislipidaemia and anaemia, as well as gender, age, ethnic minority status and positive family history. By screening and adequate treatment of modifiable risk factors we are able to prevent or delay the progression of the disease.

AIM: The aim of the study was to assess the risk factors associated with rapid progression of CKD and to see what factors are protective of slow progression.

METHODS: The study is retrospective. The medical charts of 116 patients with CKD who had been followed up for several years at the Outpatient Department of the Nephrology Clinic in Skopje were analysed. Patient age ranged from 19 to 78 years. The patients were divided into two groups: fast progressors - group I (n = 82; GFR decline > 0.1 ml/min/month) and slow progressors - group II (n = 34; GFR decline = or < 0.1 ml/min/month) with an average follow-up time of 55 months. Patients with diabetic nephropathy were excluded from the study because they are known to be fast progressors. The following variables were analysed: underlying cause of CKD, gender, age, time of follow-up, initial GFR (calculated creatinine clearance according to the Cockroft and Gault formula), final GFR, systolic and diastolic blood pressure, mean and pulse blood pressure, haemoglobin, cholesterol and 24h protein excretion rate. Progression of CKD was assessed by linear regression analysis of the mean monthly decrease of calculated creatinine clearance (delta CCcr).

RESULTS: There was no statistically significant difference between fast and slow progressors regarding their systolic, diastolic, mean and pulse arterial blood pressure. With regard to the other risk factors, it appeared that progressors are significantly younger (50.50 vs 59.20; p = 0.001, more anaemic Hb-116.68 g/l vs 123.27; p = 0.0036), more proteinuric (1.46 g/d vs 0.76; p = 0.003) and have higher diastolic blood pressure (92.25 mmHg vs 84.75 mmHg; p = 0.005) compared to non-progressors. There was no statistical difference between the groups in terms of gender (p = 0.451). Regarding renal diagnosis, there was a statistically significant difference in progression among the four diagnostic groups, p = 0.00208. Chronic glomerulonephritis (GN) was associated with significantly faster progression (delta KKK = -0.5525 ml/min/mo) compared to interstitial nephritis/nephrosclerosis (IN/NS) (delta KKK = -0.2542 ml/min/mo), p = 0.03918, and compared to unknown renal disease (Unkn) (delta KKK = -0.1487 ml/min/mo), p = 0.0245. Polycystic kidney disease (PKD) had faster progression (delta KKK = -0.5704 ml/min/mo) compared to IN/NS, p = 0.04340 and compared to Unkn, p = 0.0251.

CONCLUSION: Timely recognition of risk factors for CKD progression and their treatment by correction of high blood pressure, reduction of proteinuria, correction of anaemia and dyslipidaemia (to lower cardiovascular risk) may retard progression of CKD to end-stage renal disease, thus delaying the need for renal replacement therapy.