Background. Chronic kidney disease (CKD) has become a pandemic in recent decades, being the fifth most common cause of death from noncommunicable diseases. CKD is a risk factor for the development of cardiovascular diseases and associated mortality, and the treatment of these diseases requires significant health care costs. Early diagnosis and promptly prescribed diet and treatment for CKD can prevent or slow the progression of the disease.
Objective. Determination of the proportion of primary care patients with risk factors, signs and symptoms of CKD who are not be followed up by a nephrologist.
Material and methods. A prospective non-interventional observational study "Early diagnosis of chronic kidney disease in primary health care facilities" ("CKD screening") in routine clinical practice was carried out in 12 regions of the Russian Federation. All patients who met the inclusion criteria and had at least one sign, symptom or risk factor for CKD who visited participating primary health care (PHC) physicians during the project period were screened for the purposes of this study. Primary care physicians assessed risk factors, signs and symptoms of possible CKD using a questionnaire developed by the study authors. Patients with suspected CKD were advised to see a nephrologist. Descriptive statistics methods were used. No comparative analysis has been carried out. Continuous variables are represented by the number of observations, mean (Mean) with standard deviation (SD) and standard error (SE), first (Q1), second (Median) and third (Q3) quartiles, range of values (Min; Max).
Results. 13,968 patients visited the PHC physicians participating in the project; 1124 (8%) of them were referred to a nephrologist by the PHC physician. The diagnosis of CKD was confirmed in 95% of patients further examined by a nephrologist. Distribution by CKD stages: C1 - 2.4%, C2 - 11.6%, C3 - 71.9%, C4 - 10.8% and C5 - 2.9%. Among patients with CKD C3: 33.4% had CKD C3a and 30.7% had CKD C3b. Among patients with confirmed CKD: 59% had uncontrolled arterial hypertension (AH), 50% were over 65 years old, chronic heart failure was present in 44% of patients, diabetes - in 34%, abdominal obesity - in 32%. Other diseases were less important as a risk factor for the development of CKD. The low-protein diet was prescribed by the nephrologists in 84.6% of patients.
Conclusion. The prevalence of CKD in the Russian Federation is similar to the global rates. Among patients with CKD, stage C3 disease with high risk of progression to end-stage CKD, as well as the risk of cardiovascular mortality and morbidity prevails. The study reaffirmed that uncontrolled hypertension, age over 65, chronic heart failure, diabetes and abdominal obesity are the most important risk factors for CKD, and patients with these conditions or diseases need mandatory CKD screening. The scoring system for assessing the risks of CKD proposed by the authors, along with the traditional assessment of glomerular filtration rate and albuminuria, seems to be a suitable tool for early detection of renal dysfunction; further research to study the specificity and sensitivity of the proposed method is planned.

Keywords: kidney dysfunction, chronic kidney disease, prevalence, screening, risk factors