Hypertensive Retinopathy in Patients With Indications for Kidney Transplantation: A Cross-sectional Study

doi:10.21203/rs.3.rs-1869187/v1

Purpose: Patients with end-stage renal failure are very susceptible to hypertensive retinopathy. This study explores the relationship between hypertensive retinopathy and risk factors.

Methods: The 115 patients with end-stage renal failure are indicated for a kidney transplant. The outcome variable was the hypertensive retinopathy condition of the participants. Wong's classification of hypertensive retinopathy. Using linear regression to evaluate the association

Results: According to levels, the rate of retinal damage due to hypertension is 65.22%. When univariate analysis found the level of visual acuity was statistically significant, the other factors were not statistically significant. In multivariable logistic regression analysis, sex (odds ratio: 3.4, p<0.05), hemodialysis (odd ratio: 3.5, p<0.05), visual acuity (odd ratio: 14.0, p<0.05) is considered to be an influence factor for disease progression.

Conclusion: Sex, hemodialysis, visual acuity are factors for hypertensive retinopathy in patients preparing to receive a kidney. These results reinforce the evidence for multifactorial hypertensive retinopathy disease in patients with renal impairment.

Hospital Medicine

hypertensive retinopathy

renal failure

renal transplant

Hanoi Vietnam

The retina is a part of the eye, but some symptoms of many systemic diseases can be observed. Furthermore, some eye diseases have systemic causes[1, 2]. For many systemic disorders, monitoring at the eye allows the detection of lesions in the eye. It helps in the diagnosis, prognosis, monitoring, and evaluation of the treatment results of systemic diseases.

Hypertension retinopathy in patients with chronic renal failure is a common complication when prolonged high blood pressure [2–4]. These lesions are primarily chronic but can also be acute. Currently, kidney transplantation is still considered the most effective and economical treatment for patients with end-stage renal failure[5, 6]. Patients with indications for a kidney transplant are often examined for a general examination to evaluate the damage to organs related to kidney disease, including the eyes. These patients all underwent a thorough evaluation of the body and specialized organs. However, the comprehensive assessment of damage in the eye organ is still not focused. Patients themselves do not see that it is an urgent problem compared to the treatment of kidney disease.

In Vietnam, there are many kidney transplant centers, but there is no report on the rate of hypertension retinopathy in this subject. The specific objective of this study is: "Evaluate hypertensive retinopathy and some related factors in kidney transplant patients."

Ethical approval

was obtained according to Decision No. 467/GCN-HDDDNCSYHN-ĐHYHN dated 04/05/2021, Hanoi Medical University, Vietnam. All patients provided written informed consent, and that this study was conducted following the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

The formula for calculating sample size uses the formula for determining the sample size of a proportion of the World Health Organization [7]. The study group included 115 patients with end-stage renal failure with an indication for kidney transplantation. Only the left eye was analyzed.

Inclusion criteria

Patients diagnosed with renal failure grade 3 to 4 who are indicated for kidney transplantation with glomerular filtration rate < 60 ml/min/173m2 according to the KDIGO formula (Kidney Disease Improving Global Outcomes 2012)[8]. Chronic kidney disease is due to various causes, including chronic glomerulonephritis, hypertension, and other reasons such as polycystic kidney, chronic pyelonephritis, lupus, gout. Research in both male and female, age at the time of study is over 18, and disease detection is different.

Exclusion criteria: The systemic has a combination of acute diseases such as sepsis, respiratory failure, pneumonia, stroke. There are inflammatory diseases of the ocular surface: acute and chronic glaucoma, chronic uveitis, keratoconjunctivitis, diabetic retinopathy, and history of retinal surgery.

Variables

The outcome variable is hypertension retinopathy as graded by author Mitchell Wong [9] including the normal retina, mild, moderate, and malignant. Other variables such as best corrected visual acuity (in logMar units), intraocularpressure measured by Goldmann method (mean value is 13.42 ± 2.33 mmHg)[10]. Systemic factors include age (years), sex (male or female), body nutritional status as calculated by BMI = weight /(height/100)² [11]. Diastolic and systolic blood pressure readings (calculated as hypertension when diastolic blood pressure ≥ 140 mmHg and/or systolic blood pressure ≥ 90 mmHg) [12]. The patient was measured systolic and diastolic blood pressure (BP) with an automatic sphygmomanometer (Omron, Japan). The causes of renal failure included glomerulonephritis, hypertension, other reasons. Procedures of using dialysis (hemodialysis, peritoneal dialysis). Patient data on education, residence, history of smoking, and occupation as an estimate of socioeconomic status.

Protocol

Each participant underwent a physical examination that included a height/weight measurement in determining body mass index (BMI). Systolic and diastolic blood pressure was measured using an automatic sphygmomanometer (Omron, Japan). The patient has measured the blood pressure in the early morning, a total of three measurements, the results of which were the average of the three measurements.

Best corrected visual acuity using the Snellen electronic table at a distance of 5m, in logMAR units, divided into three levels: group reaching maximum visual acuity 0.0, group achieving visual acuity 0.1, and group 3 remaining visible acuity levels. Apply one drop of Alkain 0.1% (Alcon) to each eye, Goldmann tonometer Fluorescein stain, model BQ-900 (Haag-Streit; Haag Streit, Bern Switzerland) to obtain IOP readings from each eye. Evaluation of the anterior segment, including cornea, anterior chamber, iris, pupil, and vitreous by CSO microscope (Italy). Mydrin-P pupil dilation evaluates the posterior segment, including vitreous, optic disc, central retina.

Statistical analysis

Data entry was completed using EpiData software 3.1 (EpiData, Odense, Denmark). Statistical analysis and data cleaning with STATA 16.0 (Stata Corp, College Station, TX, USA). Quantitative data are presented as mean and standard deviation, while qualitative data were presented as absolute values and percentages. Test of normal distribution, comparing the mean of two groups by t-student test, of many groups by ANOVA test. For non-normal distributions, we test the mean of two independent groups using the Wilcoxon-Mann-Whitney test and test the mean of more than two separate groups using the Kruskal-Wallis test. Compare two proportions of one group by Chi-square test, two independent groups by Fisher test for qualitative variables. Using logistic regression equation to evaluate the association between hypertensive retinopathy with several independent systemic and ocular variables.

We compared the sign of hypertension retinopathy status and factors in patients with renal failure. The results are highlighted in Table 1.( TABLE1)

INSERT TABLE1 HERE

Table 1 shows an overview of participant characteristics, with differences in non-dialysis and dialysis with hypertensive retinopathy (p < 0.05, Fisher's test).

Table 2 provides the results obtained from the preliminary analysis of the systemic and eye characteristics. (TABLE2)

INSERT TABLE2 HERE

The differences are highlighted in visual acuity between the group with hypertension retinopathy and no lesion retina, as shown in Table 2 (p<0.05, Wilcoxon-Mann – Whitney test).

Figure 1 shows the intercorrelations between hypertension retinopathy degrees with visual acuity. (FIGURE1)

INSERT FIGURE1 HERE

We performed logistic regression to evaluate the multivariate correlation between hypertensive retinopathy in renal failure patients with indications for kidney transplantation and risk factors. The results are shown in Table 3.

INSERT TABLE3 HERE

What is striking about the figures in this table is a correlation between hypertensive retinopathy and gender, hemodialysis, and visual acuity (p < 0.05). The other factors did not show any correlation.

This study was first conducted in Vietnam on renal failure patients with indications for kidney transplantation. We found that the prevalence of hypertensive retinopathy was high in this group of patients (70.1%). Men have more retinal damage due to hypertension. Prolonged dialysis time is a factor in worsening retinal damage associated with vision loss. This study provides evidence on the prevalence of hypertensive retinal damage in renal failure patients who are indicated for kidney transplantation and also points out the existence of some related factors that may suggest guidelines for preventing or minimizing this damage.

Several reports have been shown that age is a risk factor for hypertensive retinopathy [13-15]. This study has been unable to demonstrate a correlation between age and hypertensive retinopathy in this patient population. We may explain this result because, in our study, participants were of lower age and were selected for kidney transplantation. While previous studies only studied subjects with hypertensive retinopathy alone.

A strong relationship between sex and hypertension retinopathy has been reported in the literature[13, 15, 16]. This study confirms that sex is associated with hypertension retinopathy. These results are likely related to the lifestyle and activities between the sexes [16, 17].

In reviewing the literature, data was found on the association between education and risk of chronic kidney disease[18, 19] including hypertensive retinopathy. In contrast to earlier findings, however, no evidence was detected.

Prior studies have noted the importance of regional and chronic kidney disease, highlighting that rural has a significantly higher incidence than urban[19]. However, the current study's findings do not support the previous research.

This finding is contrary to previous studies which have suggested that smoking is associated with hypertensive retinopathy as the conclusion of several previous studies [20, 21]. In general, therefore, it seems that our patients have tried to quit smoking.

These results are in accord with recent studies indicating that decreased vision acuity is a symptom of chronic kidney failure [22]. This finding, while preliminary, suggests that the assessment of retinal damage in end-stage CKD by optometry is essential.

Our results show that in the group of patients with end-stage renal failure on dialysis, the retinal damage caused by hypertension is significantly different than in the group of patients without dialysis. This finding is consistent with Pilly Chillo (20109), who concluded that the incidence of hypertensive retinopathy in patients with end-stage renal failure increases with renal disease severity.[23].

As mentioned in the literature review, that the influence of BP and BMI on small vessels[24]. However, the findings of the current study do not support the previous research.

The present study was designed to determine the effect of intraocular pressure on hypertensive retinopathy[25]. However, this study's observed difference between intraocular and hypertensive retinopathy was not significant.

The limitation of the study is the cross-sectional study design. When concluding that hypertensive retinopathy is correlated with sex, dialysis status, and visual acuity, we need a longitudinal study to monitor whether such changes occur in each patient.

The main objective of the present study was to evaluate hypertensive retinopathy and some related factors in kidney transplant patients. The prevalence of hypertensive retinopathy is high; associated risk factors are female, dialysis status, and visual acuity. The evidence from this study suggests that eye health care should be taken into account for patients before and after kidney transplantation.

BP

blood pressure

BMI

body mass index

BCVA

best-corrected vision acuity

IOP

intraocular pressure

Acknowledgments

We thank all the Department of Opthalmology and Department of Nephrology staff, and the Director board of Military Hospital 103 for supporting this study.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request. If you have concerns about sharing the data, please contact [email protected].

Ethical statements

All participants were dispensed with written informed consents, and the protocol was approved by the Ethical Review Committee of the Hanoi Medical University, Vietnam (Decision no. 467/GCN-HDDDNCSYHN-DHYHN dated 05/04/2021). All patients provided written informed consent, and that this study was conducted following the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Consent for Publication

I understand that the Eye journal may be available in print and the internet and will be available to a broader audience through marketing channels and other third parties. Therefore, anyone can read material published in the journal. I understand that readers may include medical professionals, scholarly researchers and journalists, and general public members. If you have any queries, please contact [email protected].

Disclosure

The author(s) declared no potential conflicts of interest to this article's research, authorship, and publication.

Funding

The author(s) received no financial support for this article's research, authorship, and publication.

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Table 1. Some characteristics of Participants

Hypertension retinopathy N (%)

No

Yes

p

Gender

Male

Female

26 (65)

14 (35)

59(78.67)

16 (21.33)

> 0.05

Area

Urban

Rural

17 (42.5)

23 (57.5)

34 (45.33)

41 (54.67)

> 0.05

Education

Formal education

College

28(70)

12 (30)

61(81.33)

14 (18.67)

> 0.05

Smoking

Yes

No

28(70)

12 (30)

53 (70.67)

22 (29.33)

>0.05

Hemodialysis

No

Yes

11 (27.5)

29 (72.5)

1 (1.33)

74(98.67)

< 0.05

Table 2. Characteristics of participants systemic and eyes

	Hypertension Retinopathy N, mean (SD)				p
	No		Yes		p
Age	40	36.95 (8.4)	75	37.4 (10.9)	> 0.05
SBP	40	150.4 (18.5)	75	154.6 (20.5)	> 0.05
DBP	40	90.6 (12.6)	75	91.5 (14.1)	> 0.05
BMI	40	21.2 (3.3)	75	21 (2.5)	> 0.05
VA	40	(0.2)	75	0.3 (0.3)	<0.05*
IOP	40	14.6 (2.6)	75	14.7 (2.3)	> 0.05

SBP: systolic blood pressure, DBP: diastolic blood pressure, BMI: body mass index, VA: visual acuity, IOP: intraocular pressure.

Table 3. Correlation between hypertensive retinopathy and some risk factors: logistic regression

	Model 1			Model 2			Model 3
	OR	95%CI	P	OR	95%CI	P	OR	95%CI	P
Sex Female Male	1 3.4	1.1-10.3	< 0.05	1 2.5	0.8 – 7.5	>0.05	1 2.9	1.1-8.4	< 0.05
Age	1.0	1.0 – 1.1	> 0.05	1.0	1.0 – 1.1	>0.05	2.9	1.0-1.1	> 0.05
Education	0.6	0.2 – 1.7	> 0.05
Regional	1.4	0.5-3.6	> 0.05
Smoking	0.6	0.2 – 1.7	> 0.05
Hemodialysis No Yes	1 3.5	2.0 – 6.3	< 0.05	1 3.6	2.0-6.8	<0.05	1 4.4	2.3-8.3	< 0.05
BMI				1.0	0.9-1.2	>0.05
SBP				1.0	1.0 – 1.1	>0.05
DBP				1.0	1.0-1.1	>0.05
VA							14.0	1.9-101.1	< 0.05
IOP							1.1	0.9 – 1.3	> 0.05

Hypertensive Retinopathy in Patients With Indications for Kidney Transplantation: A Cross-sectional Study

Status:

Version 1

Abstract

Figures

Introduction

Patients And Methods

Statistical analysis

Results

Discussion

Conclusion

Abbreviations

Declarations

References

Tables

Status:

Version 1