Purpose of the study: To study the content of cystatin C and to identify the factors reducing the glomerular filtration rate in patients with comorbid pathology.

Materials and methods: 383 patients with comorbid pathology aged from 25 to 88 years (mean age 58.8±12.0 years) were examined, of whom 51.4% were men and 48.6% women. In the structure of comorbid pathology, arterial hypertension (AH) was observed in 76.5%, coronary heart disease (CHD) in 48.8%, diabetes mellitus (DM) type2 in 29.7%, obesity in 47, 5% and chronic obstructive pulmonary disease (COPD) in 28.9% of patients. The examined patients were divided into 4 groups: 1st persons with hypertension+type2 diabetes (n = 99); 2nd - AH + CHD (n = 138); 3rd -AH + COPD (n = 102) and the 4th group patients with severe comorbid pathology, i.e. AH + DM + CHD + COPD (n = 44). All patients were studied for lipid spectrum parameters [total cholesterol (cholesterol), high-density lipoprotein cholesterol (HDL cholesterol), low-density lipoprotein cholesterol (LDL cholesterol), triglycerides (TG)] and cystatin C of blood plasma. The glomerular filtration rate (GFR) was calculated according to the formula F.J. Hoek. The severity of renal dysfunction was assessed according to the recommendation of KDIGO (Kidney Disease: Improving Global Outcomes) 2012. The analysis of the prevalence of reduced GFR in patients with comorbid pathology was also carried out.

Results: The presence of reduced GFR gradations of C2 and C3 “A” was detected in 46.7% and 24.8% of the examined individuals, respectively. Severe reduction in GFR was observed in 11.7% of patients. Sharply reduced GFR (C4 gradation) was significantly more frequently registered in women than in men (10.7% versus 5.0%; p <0.05). In the examined cohort, persons of middle and old age made up 36.8% and 42.2%, respectively. In patients with comorbid pathology, cases of hypercholesterolemia (41.7%), hypertriglyceridemia (45.4%) and elevated levels of LDL cholesterol (46.9%) were frequently detected, and in the 4th group, the mean age and body mass index (BMI) were significantly higher, and cholesterol levels of HDL and GFR were significantly lower compared with other groups. In the 1st group (AH+DM type2), systolic blood pressure (SBP), total cholesterol and cystatin C plasma levels were significantly higher than in the AH+CHD, AH+COPD groups and patients with severe comorbid pathologies. Higher concentrations of LDL cholesterol were observed in patients with hypertension and COPD. In the 1st group of patients, the GFR value closely correlated with age (r=-0.21; p=0.03), the level of SBP (r=-0.34; p=0.03), and concentration cystatin C of blood plasma (r=-0.87; p=0.01). In the 2nd subgroup, the GFR index was associated with the level of the SBP (r=-0.32; p=0.03) and the concentration of cystatin C in the blood plasma (r=-0.86; p=0.03). In patients with AH, COPD negative association of GFR was recorded with age (r=-0.44; p=0.03), heart rate (r=-0.36; p=0.03), total cholesterol concentration (r=-0.20; p=0.04), HDL cholesterol levels (r=-0.27; p=0.03), LDL cholesterol levels (r=-0.27; p=0.03), as well as cystatin C (r=-0.89; p=0.01). In the 4th subgroup, the magnitude of GFR was significantly correlated with the level of SAP (r=-0.33; p=0.03) and the concentration of cystatin C of blood plasma (r =-0.86; p=0.01).

Findings: In patients with comorbid pathology, the frequency of reduction in glomerular filtration rate of the C2 gradation was 46.7%, and the C3 “A” gradation was 24.8%. Severe decline in renal function was observed in 11.7% of patients, and it was more often detected in women. In comorbid pathology, a decrease in renal function is associated with the presence of hypercholesterolemia, hypertriglyceridemia, and an elevated level of cholesterol of low-density lipoprotein. In individuals with comorbid pathology, the incidence and severity of chronic kidney disease are influenced by age, body mass index, systolic blood pressure, total cholesterol and cystatin C concentrations of blood plasma.

Keywords:Cystatin C; Glomerular filtration rate; Chronic kidney disease; Comorbid pathology