The relationship between renal and retinal parameters in uncomplicated hypertension in middle-aged people

Background. Controlled arterial hypertension (HTN) does not mean complete regression of preclinical target organ damage. Objective. To study the relationship between indicators characterizing the structural and functional state of the kidneys and retina in middle-aged patients with uncomplicated HTN, receiving combination antihypertensive therapy (AHT) and having office systolic (SBP) and diastolic (DBP) blood pressure levels < 140 and < 90 mmHg. Design and methods. We examined 87 patients (65 males and 22 females, average age 50,5 ± 4,87 years) with stage I and II HTN without clinically significant concomitant pathology taking double combined AHT (group average office level of SBP and DBP 134 ± 12,3 and 84 ± 14,5 mmHg, respectively). For at least the previous 12 months, patients had regularly received voluntary dual combination AHT based on pharmacological blockade of the renin-angiotensin-aldosterone system. HTN patients underwent a comprehensive assessment of the structural and functional state of the kidneys and fundus of the eye. To assess the relationships between biomarkers of kidney and retinal damage in the examined individuals within the entire set of studied parameters, correlation analysis and comparative analysis of the same quantitative (renal or retinal) indicators were used in subgroups of individuals divided according to a conditionally selected qualitative characteristic corresponding to the norm or deviation from the norm (value central retinal arterial equivalent (CRAE ≥ or < 145 μm), central retinal venous equivalent (CRVE ≥ or < 227 μm), albumin-creatinine ratio (ACR ≥ or < 10 mg/g), foveal avascular zone area (FAZ ≥ or < 0,36 mm²). Statistical processing of data was carried out using the Basic Statistics / Tables modules of the application package Statistica for Windows (version 12). The relationship between quantitative renal and retinal indicators was studied using the Pearson r correlation coefficient. Comparative analysis of quantitative parameters within the examined group, conditionally subdivided according to a certain qualitative criterion, was performed using the nonparametric Mann-Whitney U-test. Results. CRVE values directly correlated with ACR (r = 0,30; p = 0,037), FAZ area — with ACR (r = 0,40; p = 0,005), subfoveal choroidal thickness (SCT) — with estimated glomerular filtration rate (eGFR) (r = 0,45; p = 0,001); CRAE values inversely correlated with serum urea (r = –0,34; p = 0,019), SCT — with serum creatinine (r = –0,36; p = 0,011). Patients with ACR ≥ 10 mg/g compared with patients with ACR < 10 mg/g were characterized by significantly lower values of the retinal arteriovenous ratio (0,646 ± 0,09 and 0,689 ± 0,08, respectively, p = 0,016). Patients with FAZ area ≥ 0,36 mm² compared with those with FAZ area < 0,36 mm² had higher proteinuria values (0,101 ± 0,13 and 0,075 ± 0,14 mg/g, respectively, p = 0,01). Conclusions. Middle-aged patients with uncomplicated HTN without clinically significant concomitant pathology, receiving double combined AHT, demonstrate significant associations of indicators characterizing the structural and functional state of the kidneys and retinal microcirculation in terms of their preclinical damage.