Carotid intima-media thickness, flow-mediated dilatation and proteinuria in patients of human immunodeficiency virus-positive patients: A case-control study.

INTRODUCTION: Endothelium-dysfunction (ED) is a surrogate marker of coronary atherosclerotic disease. Carotid intima-media thickness (CIMT), flow-mediated dilatation (FMD), and proteinuria are surrogate markers of ED. Few studies have shown that patients with HIV have impaired endothelial function and are thus at risk of accelerated atherosclerosis.
MATERIALS AND METHODS: The present study assessed ED in HIV patients by various biophysical parameters as brachial artery FMD, CIMT, and proteinuria. A total of 43 HIV-infected patients were compared with 25 healthy controls who were healthy.
RESULTS: Mean age of patients with HIV was 33.84 ± 5.61 years while that of healthy controls was 31.48 ± 5.40 years. Male to female ratio among cases was 24:19 while among controls was 17:8. Mean CIMT was significantly higher among cases than control (0.513 ± 0.079, 0.452 ± 0.050 mm, respectively, P = 0.001). Percentage change in FMD was significantly lower among cases than control (3.27 ± 2.01, 6.96 ± 1.28, respectively, P = 0.001). Urine protein grading was significantly different between cases and controls (P = 0.007), with stable HIV cases having significantly higher urine protein grading compared to healthy controls. However, no correlation was seen between CIMT, FMD, and proteinuria overall among cases and controls.
CONCLUSIONS: HIV-infected patients have significant impairment of endothelial function, in the form of increased CIMT, impaired FMD, and more proteinuria as compared to healthy controls.

Introduction

HIV-infected patients are at higher risk for cardiovascular events.[1] Thus, we need to identify the patients at risk at the earliest using easily obtainable, noninvasive, and inexpensive markers. Endothelial dysfunction (ED) is an early step that leads to progression of atherosclerosis. Proteinuria is another marker which predicts future cardiovascular events.[2]

The development of systemic ED has been suggested as the link between the presence of proteinuria and development of cardiovascular disease.[3] Not only HIV, its therapies have also been associated with ED.[4] Endothelial function can be assessed by flow-mediated dilatation (FMD).[5] Carotid intima-media thickness (CIMT) is a measure of the extent of early arterial wall changes. Increased carotid IMT is a strong predictor of acute coronary events.[6] Thus, we conducted a study to look at the endothelial cell dysfunction in stable HIV patients and compare with healthy controls.

Materials and Methods

The study population included forty-three consecutive stable HIV patients attending Medical OPD and HIV clinic at a tertiary care hospital at New Delhi.

The aims of our study were:

To study endothelial cell dysfunction in stable HIV patients as a marker of premature atherosclerosis by FMD, proteinuria, and carotid intima-media thickness

To study its correlation with healthy controls.

We included stable patients of HIV (confirmed by IGM ELISA).

Patients with age <18 years and >40 years, overweight (body mass index >25 kg/m2), suffering from preexisting diabetes mellitus or hypertension, receiving highly active antiretroviral therapy, suffering from known renal disease (serum creatinine >1.4 mg/dl or >124 μmol/L), history of cardiovascular and ischemic heart disease, fever (temperature >38.0°C) currently or 2 days before enrolment in the study, suffering from any opportunistic infection, smokers, alcoholics, or other active substance abuse, on drugs such as growth hormone, systemic steroids, ketoconazole, any form of estrogen, progesterone, testosterone, or any anabolic agents within 3 months before enrolment in the study and pregnant women were excluded from the study.

Twenty-five apparently healthy controls were residents and nurses working in the same tertiary care hospital. Exclusion criteria for controls were same as that for the HIV cases.

All the patients and controls in the study group were subjected to detailed history and physical examination. Informed consent was taken from both cases as well as controls. The study protocol has been evaluated and approved by the hospital Ethical Committee.

Following investigations were carried out in all the patients and controls:

Brachial FMD using 10MHZ linear array transducer

Common Carotid Ultrasonography-Using 7.5MHZ B-mode ultrasound with high-density lipoprotein 3500 machine, (ATL, USA) equipped with color flow imaging and pulse Doppler and one examiner examined the result of all the patients

Urine examination-single spot urine sample for proteinuria and cells/casts was obtained.

Statistical analysis

The data of all patients were entered into Microsoft Excel version 2007. The data analysis was done by the SPSS software for window version 17(IBM Corporation, New York, United States). Quantitative variables were reported as mean ± standard deviation and were compared by Student's t-test or Mann–Whitney test as appropriate. One-way analysis of variance (ANOVA) model was used to compare cases and controls for difference of urine protein grading. Qualitative variables were reported and compared by Chi-square test or by Fischer's exact test as appropriate. P < 0.05 was considered statistically significant. Continuous variables were correlated using Pearson's correlation coefficient.

Results

Our study included 43 cases and 25 healthy controls. Proteinuria was estimated by dip stick method which is represented in Table 1. Baseline characteristics of both cases and controls are shown in Table 2.

Table 1

Dipstick proteinuria ranges

Table 2

Baseline characteristics of cases and controls

The studied parameters were compared which is shown in Table 3.

Table 3

Comparison of studied parameters between cases and controls

Urine protein was also compared among cases and controls which is shown in Table 4.

Table 4

Comparison of urine protein grading between cases and controls

Urine protein grading was significantly different between cases and controls (P = 0.007), with stable HIV cases having significantly higher urine protein grading compared to healthy controls (one-way ANOVA). In urine microscopy, cells and casts were absent both in cases and controls.

The association between the parameters was calculated which is shown in Table 5.

Table 5

Association between various studied parameters overall in cases and controls

Discussion

In this study, we studied forty-three stable HIV patients and twenty-five apparently healthy controls and looked for any significant difference between stable HIV patients and controls with respect to CIMT, FMD, and proteinuria and examined the relationship between CIMT, FMD, and proteinuria and their use as a marker of ED for premature atherosclerosis.

In our study, we found higher baseline mean CIMT in HIV-positive patients (0.513 ± 0.079 mm), as compared to controls (0.452 ± 0.050 mm) with a significant difference (P = 0.001). Table 6 summarizes previous major studies on CIMT in HIV patients.

Table 6

Summary of previous major studies on carotid intima media thickness in human immunodeficiency virus patients

In our study, we excluded the patients on HAART to prevent its effect on CIMT.

We also found that in stable HIV patients have increased in brachial artery diameter in response to passive hyperemia which was significantly lower as compared to healthy controls (3.27 ± 2.01 mm vs. 6.96 ± 1.28 mm, P < 0.001). Furthermore, significantly lower HIV cases had percent FMD ≥4.5% as compared to controls (23.3% vs. 100%, P < 0.001). Table 7 summarizes previous major studies of FMD in HIV patients.

Table 7

Summary of previous major studies on flow-mediated dilatation in human immunodeficiency virus patients

Our finding of unequal percentage FMD in HIV patients and non-HIV participants is in agreement with previous studies that found decreased FMD in HIV patients compared to HIV-uninfected controls[2122] but in contrast to other studies[1920] that found equal FMD in HIV patients and non-HIV participants. Various explanations have been proposed for conflicting results regarding brachial FMD in the literature. These include heterogeneity in patient populations being studied, different measurement protocols or inadequate sample sizes.

We also found significant difference in urine protein grading between stable HIV cases and healthy controls, with overall urine protein grading significantly higher in HIV cases compared to healthy controls (P = 0.007). Table 8 summarizes the previous major studies on proteinuria in HIV patients.

Table 8

Summary of previous major studies on proteinuria in human immunodeficiency virus patients

The high prevalence of proteinuria in this cohort of HIV-infected patients in our study is similar to earlier reports[2324] from HIV-infected children and adults. The implication of this observation is that markers of kidney damage such as proteinuria should be searched for in HIV-infected patients with advanced clinical and or immunological stage of HIV disease.

We also found a weak inverse relationship between carotid IMT and brachial percent FMD but not significant (r = −0.197, P = 0.107), when data were combined both for HIV cases and healthy controls. There is only one previous study by Odueyungbo et al.[29] (257 HIV patients), that has validated this correlation in HIV patients with borderline significance (r = −0.126, P = 0.043).

We did not find any significant correlation between percentage FMD and proteinuria, overall in HIV cases and healthy controls (P = 0.177). After an extensive review of literature, we could find only one pilot study of its kind to study the relation between FMD and proteinuria in stable HIV patients. This study by Gupta et al.[30] of 34 stable HIV patients (28 nonproteinuric and 6 proteinuric), also could not establish any significant correlation between proteinuria and FMD.

We did not find any significant correlation between CIMT and proteinuria (P = 0.764), overall in HIV cases and healthy controls and also, separately for HIV cases (P = 0.178). To the best of our knowledge, this is the first study of its kind to study the association between CIMT and proteinuria.

Although HIV infection appears to be associated with substantial impairment of endothelial function, the degree to which this impairment translates into increased risk for cardiovascular disease in persons with HIV infection is still largely unknown. Large prospective, well-controlled studies are required to demonstrate that impaired endothelial functions translate into increased cardiovascular events and premature death in stable HIV patients.

Several limitations of our study need attention. First, the sample size of our study was small, limiting our ability to detect potentially clinically important associations. Second, proteinuria was determined by a semi-quantitative measure of urine protein concentration (dipstick), which is inferior to quantitative measures such as protein-to-creatinine ratio from a random or 24-h sample. Third, other potential confounders that were not accounted for include diet, physical activity, duration of HIV infection, and CD4 count.

Conclusions

Indian stable HIV patients have increased ED, as evidenced by increased carotid intima-media thickness, impaired FMD, and higher proteinuria. This subclinical ED would probably translate into premature atherogenesis and increased vascular events in these patients. However, the correlation between these various surrogates of endothelial cell function was poor in Indian stable HIV patients.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.