Abstract

Background: Patients diagnosed with chronic kidney disease (CKD) have a heightened risk of developing masked uncontrolled hypertension (MUCH), leading to hypertension-induced organ damage. This study aimed to estimate the prevalence and characteristics of MUCH and to investigate risk factors of left ventricular hypertrophy (LVH) in those with CKD.

Methods: A retrospective study was conducted on data from 178 patients diagnosed with CKD and having controlled office blood pressure at Nhan Dan Gia Dinh Hospital between October 2018 and June 2019. These participants underwent 24-hour ambulatory blood pressure monitoring (ABPM) using the SunTech Oscar 2 device. Subsequently, echocardiography was performed to assess for the presence of LVH.

Results: The prevalence of MUCH was 48.9%. Notably, all patients with MUCH demonstrated elevated nighttime blood pressure. LVH was more prevalent in the MUCH group when compared to those with controlled hypertension (55.2% and 38.5%, respectively). MUCH and CKD staging 4-5 were independent risk factors of LVH with ORs 1.97 (95% CI, 1.03-3.85) and 2.58 (95% CI, 1.16-5.94), respectively.

Conclusions: We recommend routinely using ABPM to detect MUCH in CKD patients even with controlled office hypertension. Screening for LVH is necessary in those with MUCH.

Introduction

Ambulatory blood pressure monitoring (ABPM) provides valuable data on mean 24-hour, daytime, and nocturnal blood pressure (BP). Patients with masked uncontrolled hypertension (MUCH) exhibit controlled office BP but elevated out-of-office BP. Similar to sustained hypertension, MUCH increases the risk of cardiovascular events and mortality compared to controlled BP1, 2. Notably, MUCH in CKD patients contributes to the progression of left ventricular hypertrophy (LVH) and end-stage renal disease (ESRD), but there are few related studies on the Vietnamese CKD population3, 4, 5. Therefore, this study aimed to estimate the prevalence and characteristics of MUCH and to examine the risk factors associated with left ventricular hypertrophy (LVH) in individuals with chronic kidney disease (CKD).

Method Study design and participants

We revisited data from 196 patients with CKD and controlled office BP undergoing 24-hour ABPM at Nhan Dan Gia Dinh Hospital from October 2018 to June 2019 with the following study criteria as follows:

Inclusion criteria were (1) age ≥ 18 years and consented, (2) an estimated glomerular filtration rate (eGFR) by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI, 2009) equation 6, and (3) controlled office blood pressure with systolic BP 120-139 mmHg and diastolic BP 80-89 mmHg7. Exclusion criteria included patients with acute illness, pregnancy, acute glomerulonephritis, systemic lupus erythematosus, as well as those with ESRD receiving renal replacement therapy.

We excluded 4 patients since they stopped engaging in the study and 14 patients who had inadequate ABPM recordings, thus yielding 178 subjects completing the investigation. The recruitment flow is illustrated in Figure 1.

× Figure 1 . Recruitment flow . Figure 1 . Recruitment flow . Data collection

Office BP readings were taken from the Yamasu sphygmomanometer, Japan, by trained nurses at clinics. Three sitting readings were recorded in a row, and office BP was calculated as the average of the last two measurements. Ambulatory blood pressure in 24 hours was measured by the American SunTech Oscar 2 device. The size of the cuff was selected according to the patient's arm circumference. AccuWinPro version 3.0 software was used to process the results. The daytime and nighttime measuring intervals were set to be every 30 minutes and 60 minutes, respectively. BP readings were not displayed on the meter screen. Patients with acceptable BP measurements greater than 70% of total measurements were considered to have adequate ABPM assessments. Controlled office BP was defined as having systolic BP 7. Left ventricular mass (LVM) was assessed by echocardiography. The procedure was performed by a certified cardiologist using an American Philips Affiniti 50G ultrasound machine. LVM (g) was calculated by the equation 0.832 x [(IVSd + LVEDd + PWTd)³ – LVEDd³] + 0.6 (g) in which LVEDd: LV end-diastolic dimension (mm), IVSd: interventricular septal thickness at end-diastole (mm), PWTd: posterior wall thickness at end-diastole (mm). LVM index was expressed as LVMI = LVM/Body surface area (g/m²) in which body surface area = 0.007184 x W⁰.⁴²⁵ x H⁰.⁷²⁵ (m²) (W = Weight, H = Height). LVH was defined as LVMI ≥ 115 g/m² in men and LVMI ≥ 95 g/m² in women8. Serum creatinine and other laboratory tests were measured at Nhan Dan Gia Dinh Hospital. Quality control for laboratory testing complied with the regulations of the Vietnamese Ministry of Health. Grading of CKD was based on eGFR6.

Statistical analyses

Continuous variables with normal distribution were displayed as the means ± standard deviation (SD). Continuous variables with skewed distributions were presented as the medians (M25–M75). Shapiro–Wilk test of normality was used to determine the normal distribution of data. Categorical variables were presented by percentage (%) and compared using the Chi-squared test or Fisher’s exact test when appropriate. For continuous variables, we compared the average values of the two groups by Student’s t-test. In the case of a non-normal distribution, a Mann–Whitney non-parametric test was utilized. Univariate and multivariate logistic regression analyses were conducted to ascertain risk factors of LVH. Multivariate logistic regression analysis was done using confounders that were significant in the univariate model. Univariate and multivariate logistic regression analyses examined 1-SD changes in continuous variables. The presence of dichotomous variables was coded as 1 and the absence as 0. All probabilities were expressed as 2-tailed, with statistical significance inferred at P

Results

A total of 178 patients with CKD and controlled office BP completed the study. After assessing 24-hour ABPM, 87 patients had MUCH (48.9%) and 91 patients were in the CH group.

Baseline characteristics

Compared with patients with CH, those having MUCH had longer hypertension duration at baseline. There was no significant difference in CKD stages between the two groups. Notably, LVH was more prevalent in the MUCH group. All laboratory results did not have a statistically significant difference in the two groups (Table 1).

Table 1.

Baseline characteristics according to BP groups

All (N = 178) MUCH (N = 87) CH (N = 91) P-value Age (year) 68.2 ± 8.8 67.5 ± 9.2 68.8 ± 8.4 0.558 Male 92 (51.7) 41 (47.1) 51 (56.0) 0.294 BMI (kg/m 2 ) 24.4 ± 3.0 24 ± 3.2 24.7 ± 2.8 0.079 Current smoker 24 (13.5) 14 (16.1) 10 (11.0) 0.627 CKD staging G3a G3b G4 G5 53 (29.8) 85 (47.8) 33 (18.5) 7 (3.9) 23 (26.4) 42 (48.3) 18 (20.7) 4 (4.6) 30 (33.0) 43 (47.3) 15 (16.5) 3 (3.3) 0.738 Diabetes mellitus 114 (64.0) 55 (63.2) 59 (64.8) 0.876 Dyslipidemia 162 (91.0) 78 (89.7) 84 (92.3) 0.606 Stroke 13 (7.3) 6 (6.9) 7 (7.7) 0.999 Heart failure 9 (5.1) 5 (5.7) 4 (4.4)