Low CD4 Cell Counts Are Associated with Carotid Plaque and Intima–Media Thickness in Virologically Suppressed HIV-Infected Asians Older Than 50 Years

Abstract

Information about the prevalence, and risk factors for subclinical atherosclerosis in an Asian HIV-infected population is limited. Carotid intima–media thickness (cIMT) is one predictor for the risk of cardiovascular disease (CVDs) and mortality. We evaluated the prevalence and risk factors related to carotid atherosclerosis among well-suppressed HIV-infected adults receiving long-term ART from Thailand. This was a cross-sectional study of HIV-infected adults >50 years of age and free from CVDs from Thailand during 1 March 2016 and 30 May 2017. Ultrasonography of the carotid was performed and read by cIMT experienced neurologists who were blinded from the patient care. Subclinical atherosclerosis was defined by carotid plaque or cIMT of the common carotid artery (CCA) >0.9 mm. Totally 316 HIV-infected adults (61% males) were included. Median age was 54.4 years and 15.8% were diabetic, 40.2% had hypertension, and 12.7% were current smokers. The median duration of ART was 16.3 years and 32% were currently on boosted protease inhibitor. The mean overall cIMT of the common carotid arteries were 0.63 (IQR 0.55–0.72) mm. Men had higher cIMT than women, 0.64 (IQR 0.56–0.76) vs. 0.60 (IQR 0.53–0.70), p = .03. Overall, 3.8% had cIMT >0.9 mm and 24.4% had carotid plaque. From the multivariate logistic regression analysis, age per 1 year increase [odds ratio (OR) 1.06; 95% confidence interval (CI) 1.003–1.12; p = .04] and nadir CD4 < 200 cells/mm³ (OR 1.8; 95%CI 1.02–3.18, p = .04) were significantly associated with subclinical atherosclerosis. High-sensitivity C-reactive protein was not associated with subclinical atherosclerosis. In this well-suppressed HIV-infected Aging Asian cohort with relatively low prevalence of current smokers, 26.9% of them had subclinical atherosclerosis. Advanced age and low nadir CD4 cell count were significantly associated with subclinical atherosclerosis. Given that approximately a quarter of the patients had carotid plaques, longitudinal studies to evaluate the development of future overt coronary artery disease and stroke are warranted.

Introduction

The risk of atherosclerosis and cardiovascular disease (CVD) seems to be higher among HIV-infected patients versus HIV-uninfected population.^1,2 However, there are limited data describing CVDs among HIV-infected compared with HIV-uninfected Thais. Although the pathogenic mechanisms of higher CVD risks are poorly understood, existing data suggest an interplay between traditional CVD risk and factors related to HIV infection, including antiretroviral therapy (ART) and chronic inflammation, play important roles in driving atherosclerosis.^2
–4 Given the high morbidity and mortality related to CVDs, early interventions to reduce CVD risk are important.

With the campaign to “end AIDS in 2030” and scale up of life saving ART in many countries, the population of aging individuals living with HIV has increased, and the incidence of CVDs is expected to rise. There is therefore a need to understand the burden and risk of subclinical atherosclerosis in this population, to enable the National HIV program to develop appropriate strategies to prevent CVD risk among HIV-infected individuals.

Atherosclerosis is commonly found in the coronary and carotid arteries.⁵ Atherosclerosis has a long latent period from onset to developing overt clinical disease, so measuring subclinical atherosclerosis may have important implications for understanding its progression to clinical disease. It also offers the possibility of early intervention to prevent or eliminate the vast majority of future atherosclerotic cardiovascular disease (ASCVD) in clinical and public health practice. Measurement of carotid intima–media thickness (cIMT) and atherogenic plaques using ultrasound is a noninvasive, sensitive, and reproducible method to identify and predict the risk for developing CVDs and mortality in the general population.⁶ cIMT is a known surrogate marker for atherosclerosis,⁷ and is significantly related to myocardial infarction, coronary artery disease, and stroke in patients without symptomatic ASCVD.^8,9 Additionally, carotid plaque and/or cIMT levels >0.9 mm among HIV-infected populations show a highly significant association with all CVDs.^10,11

cIMT and carotid plaques have been shown to be associated with future risk of ASCVD, independent of traditional risk factors. The vast majority of studies have been conducted in the United States and Europe,^{5

–9,11,12} but the prevalence of coronary atherosclerosis among people of different ethnicities is likely to be different and few studies have documented subclinical atherosclerosis among HIV-infected adults from Asia.^13,14 In this study, we measured cIMT to determine the prevalence of subclinical atherosclerosis among an aging HIV-infected population from Thailand, who had been on long-term cART for a median of 16 years. We also evaluated the predictive risks and the correlation between high-sensitivity C-reactive protein (hs-CRP) with abnormal cIMT.

Methods

Study population and design

This cross-sectional study was conducted on 1 March 2016 and 30 May 2017. HIV-infected participants >50 years of age who had received cART for more than 1 year in a long-term cohort (HIV-NAT 006: clinical trial number NCT00411983) at the HIV Netherlands Australia Thailand Research Collaboration (HIV-NAT), Bangkok, Thailand, were asked to participate in this study. Participants with known CVDs, including myocardial infarction, silent myocardial infarction, myocardial ischemia, angina pectoris (stable and unstable), ischemic or hemorrhagic stroke, and those who had previously undergone coronary procedures, such as coronary angioplasty and coronary artery surgery, in addition to those currently treated for opportunistic infection, or who were pregnant, were excluded. This study was approved by the Ethics Committee of the Faculty of Medicine, Chulalongkorn University. All participants provided written informed consent to participate in the study.

Study participants were given a physical examination, where heart rate, blood pressure, weight and height measurements, waist and hip circumferences were assessed. Lipodystrophy was captured from medical history. Blood samples were obtained after a 12 h overnight fast for complete blood count, fasting plasma glucose, lipid profiles, CD4 counts, HIV-1 RNA, and hs-CRP (Roche Diagnostics GmbH, Mannheim, Germany). Kidney function was assessed by the Chronic Kidney Disease Epidemiology Collaboration¹⁵ (CKD-EPI formula). Chronic kidney disease (CKD) ≥ stage III was defined as having had two consecutive (>6 months apart) estimated glomerular filtration rate measurements (eGFR) of ≤60 mL/min/1.73 m².

Based on the modified NCEP/ATPIII and International Diabetes Federation (IDA) criteria for Asians,¹⁶ metabolic syndrome was defined as having three or more of the following components: (1) waist circumference >90 cm in men or >80 cm in women; (2) systolic blood pressure (SBP) ≥130 mm Hg or diastolic blood pressure (DBP) ≥85 mm Hg or use of antihypertensive medications; (3) triglyceride (TG) ≥150 mg/dL or use of lipid-lowering medications; (4) fasting blood glucose ≥100 mg/dL, physician-diagnosed diabetes or use of antidiabetic medications; and (5) HDL-c < 50 mg/dL in women or <40 mg/dL in men. Diabetes Mellitus (DM) was defined as having fasting plasma glucose ≥126 mg/dL on two consecutive study visits, or reported onset of diabetes and initiation of antidiabetic therapy. Hypertension (HT) was defined as SBP ≥140 mm Hg or diastolic blood pressure (DBP) ≥90 mm Hg on two or more clinic visits over a 6-month period and/or initiation of antihypertensive therapy.

Participant cardiovascular risk was determined by ASCVD risk calculators.¹⁷ Participants were categorized as high risk (≥7.5% ASCVD risk) or low risk (<7.5% risk). Body mass index (BMI) was calculated as weight in kilograms divided by the square of the height in meters, then categorized as <18.5 (underweight), >18.5–23 (normal), >23–24.9 (overweight), or ≥25 (obese) as per the BMI criteria for Asians by the Regional Office for the Western Pacific Region of WHO.¹⁸

cIMT measurement

Carotid Doppler ultrasound was performed by a well-trained neurologist who was blinded from the patient care. A GE LOGIQ 9 model (LOGIQ 9; GE Medical System, Milwaukee, WI) ultrasound machine equipped with a 9MHz linear probe was used. Images of the three segments of the CCA: proximal, middle, and distal (1 cm distal to the bifurcation) were separately obtained longitudinally. Far wall cIMT images were obtained and digitalized for each patient. The mean of the three measurements of each side (right and left) were used for each site to calculate the mean for all proximal, mid, and distal CCAs, to provide an overall cIMT measurement. The average distance between the inner echogenic line representing the luminal–intimal interface and the outer echogenic line representing the media–adventitia interface was measured. Carotid plaque was defined as a thickness more than 1.5 mm measured from the luminal–intimal interface to the media–adventitia interface.¹⁹

Statistical analysis

According to the joint European Society of hypertension and European Society of cardiology guidelines 2018, subclinical atherosclerosis was defined as having cIMT >0.9 mm or having carotid plaques. We also did a subgroup analysis of subclinical atherosclerosis, using cIMT >0.78 mm or having carotid plaques because cIMT >0.78 was found to correlate with aortic atherosclerosis accessed by transesophageal echocardiography, and cardiovascular sources of embolus.²⁰ Continuous covariate parameters were summarized by median (IQR) and compared between atherosclerosis groups using t-tests or Wilcoxon rank-sum tests as appropriate. Categorical data were expressed as n (%) and formal comparisons between study groups were made with a chi-square or Fisher's exact test, as appropriate.

Multiple logistic regression with an outcome of prevalence of subclinical atherosclerosis was used to predict the relationship between other covariates. Potential predictor covariates included sociodemographics, HIV disease makers, and history of ARV, traditional CVD risk factors, and biomarker concentrations. Covariates with a p ≤ .10 in univariate analysis were included in the multivariate model. Statistical significance was set at 0.05. All data were analyzed using STATA 14.2 (StataCorp, College Station, TX).

Results

Baseline characteristics and cIMT data

cIMT was performed on 329 HIV-infected patients; 13 participants previously had CVDs and hence were excluded, leaving 316 in this analysis. Baseline demographics and clinical characteristics are shown in Table 1.

Table 1.

Demographic Characteristics of HIV-Infected Patients With and Without Subclinical Atherosclerosis

Characteristics	Total (n = 316)	Normal (N = 231)	Subclinical atherosclerosis (N = 85)	p-value
Age, year	54.4 (51.7–59.4)	54.1 (51.4–57.6)	57 (52.9–61.6)	.0003
Male, N (%)	193 (61.1)	133 (57.6)	60 (70.6)	.04
Smoking, N (%)				.04
Never smoker	208 (65.8)	161 (69.7)	47 (55.3)
Former smokers	68 (21.5)	42 (18.2)	26 (30.6)
Current smokers	40 (12.7)	28 (12.12)	12 (14.1)
Family history CVD, N (%)	151 (48.4)	110 (48.46)	41 (48.24)	.97
ASCVD risk score	6 (2.8–11.5)	5.2 (2.5–10.2)	8.9 (4.7–16.4)	.0002
ASCVD risk score >7.5%, N (%)	128 (40.5)	82 (35.5)	46 (54.1)	.003
Diabetes mellitus, N (%)	50 (15.8)	32 (13.9)	18 (21.2)	.11
Hypertension, N (%)	127 (40.2)	86 (37.2)	41 (48.2)	.08
Ever used Statin drug, N (%)	128 (40.5)	87 (37.7)	41 (48.2)	.09
Current statin use, N (%)	92 (29.1)	63 (27.3)	29 (34.1)	.24
Body mass index, kg/m²	23.2 (20.8–25.4)	23.3 (21–25.4)	22.9 (20.5–24.8)	.22
18.5–22.9, N (%)	124 (39.2)	87 (37.7)	37 (43.5)
23–24.9, N (%)	80 (25.3)	59 (25.5)	21 (24.7)
>25, N (%)	89 (28.2)	68 (29.5)	21 (24.7)
Waist circumference >80 cm for women and >90 cm for men, N (%)	122 (38.6)	94 (40.7)	28 (32.9)	.21
Waist/hip ratio	0.93 (0.88–0.97)	0.92 (0.88–0.97)	0.93 (0.88–0.97)	.72
Hepatitis B infection, N (%)	41 (12.8)	33 (14.3)	8 (9.4)	.25
Hepatitis C infection, N (%)	28 (8.9)	22 (9.6)	6 (7.1)	.48

Subclinical atherosclerosis defined as CIMT >0.9 mm and/or carotid plaques.

CVD, cardiovascular disease; ASCVD risk, atherosclerotic cardiovascular disease risk.

The overall median age was 54.4 years, 61.1% were males, and 12.7% were current smokers (21.5% former smoker, and 65.8% never smoked). All participants had been taking ART for a median duration of 16.3 years. The most common current ART regimen was 2 NRTI (tenofovir disoproxil fumarate and lamivudine or emtricitabine) plus an NNRTI (55.4%) or boosted protease inhibitor (32%). Only 11.1% had been exposed to abacavir for a median duration of 1.0 (IQR 0.1–3.5) years. Current median CD4 cell count was 628 cells/mm³ and 96.8% had plasma HIV RNA <50 copies/mL. No participants had opportunistic infections when cIMT was performed.

Subclinical atherosclerosis

The median overall cIMT of the common carotid arteries was 0.63 (IQR 0.55–0.72) mm. As expected, cIMT was thicker in males than females 0.64 (IQR 0.56–0.76) versus 0.60 (IQR 0.53–0.70), p = .03. Overall, 12 (3.8%) participants had cIMT >0.9 mm and 77 (24.4%) had carotid plaques, giving a total of 85 patients with subclinical atherosclerosis and a prevalence of 26.9%. Demographics, comorbidities, and ART information are compared between subclinical atherosclerosis groups in Tables 1 and 2, respectively.

Table 2.

HIV-Disease and Antiretroviral Therapy Characteristics Among HIV-Infected Patients With and Without Subclinical Atherosclerosis

Characteristics	Total (n = 316)	Normal (N = 231)	Subclinical atherosclerosis (N = 85)	p-value
Duration of HIV infection, year	18.5 (15–20.9)	17.9 (14.8–20.7)	19.7 (15.9–21.9)	.05
Duration of ART, year	16.3 (12.4–19.1)	16.2 (11.9–18.8)	16.7 (14.9–19.7)	.00
Current ART regimen, N (%)				.01
NNRTI	175 (55.4)	139 (60.2)	36 (42.4)
PI	101 (31.9)	69 (29.9)	32 (37.7)
Both NNRTI and PI	24 (7.6)	12 (5.2)	12 (14.1)
Others	16 (5.1)	11 (4.8)	5 (5.9)
Lopinavir/ritonavir exposure, N (%)	137 (43.4)	99 (42.9)	38 (44.7)	.77
Duration of Lopinavir/ritonavir, years	3.2 (1.6–6.6)	3.1 (1.6–6.7)	3.3 (1.2–6.2)	.98
Atazanavir/ritonavir exposure, N (%)	101 (31.9)	69 (29.9)	32 (37.7)	.19
Duration of Atazanavir/ritonavir, year	3.9 (1.6–6.8)	3.8 (1.5–6.8)	4.0(2.4–7.4)	.48
Efavirenz exposure, N (%)	188 (59.5)	142 (61.5)	46 (54.1)	.24
Duration of efavirenz exposure, year	7.0 (2.8–11.8)	7.3 (2.8–11.6)	6.2 (3.2–13.5)	.74
Abacavir exposure, N (%)	35 (11.1)	25 (10.8)	10 (11.8)	.81
Duration of abacavir exposure, year	1.0 (0.1–3.5)	0.5 (0.1–1.9)	1.9 (0.3–3.7)	.21
Stavudine exposure	197 (62.30)	142 (61.5)	55 (64.70)	.60
Duration of stavudine exposure, year	3.0(1.20–5)	3.1(1.2–4.8)	3 (1.9–5.6)	.42
Current CD4, cells/mm³	628 (485–814)	627 (489–815)	649 (444–803)	.44
<500 cells/mm³, N (%)	92 (29.1)	63 (27.3)	29 (34.1)	.24
Nadir CD4, cell/mm³	176 (81–260)	191 (101–264)	143 (57–235)	.04
NadirCD4 < 200 cells/mm³	179 (56.7)	120 (52)	59 (69.4)	.01
Current HIV RNA <50 copies/mL, N (%)	303 (96.8)	224 (98.3)	79 (92.9)	.02
Lipodytrophy/lipoatrophy	182 (57.59)	124 (53.68)	58 (68.24)	.02

Subclinical atherosclerosis defined as CIMT >0.9 mm and/or carotid plaques.

NRTI, nucleoside reverse transcriptase inhibitor; NNRTI, non-nucleoside reverse transcriptase inhibitor; PI, protease inhibitor; ART, antiretroviral therapy.

The subclinical atherosclerosis group had significantly higher traditional risks for ASCVD (older age, male sex, had ever smoked, longer duration of ART use, lower nadir CD4 cell counts, higher lipodystrophy prevalence, and Fib-4 scores). Additionally, the subclinical atherosclerosis group had higher median 10-year risk of CVDs (8.9% vs. 5.2%, p = .0002) and a higher proportion of participants had 10-year risk of CVDs >7.5% (54.1% vs. 35.5%, p = .003) by the ASCVD equation.

In the subgroup analysis, 47 participants (14.9%) had cIMT >0.78 mm, and 77 (24.4%) had carotid plaques, giving a total of 108 patients with subclinical atherosclerosis (34.2%). Demographic data among subclinical atherosclerosis (cIMT >0.78 mm/carotid plaque) and normal groups were similar to the demographic data mentioned above for the cIMT >0.9 mm/carotid plaque group. Additionally, the subclinical atherosclerosis group had higher median 10-year risk of CVDs (9.3% vs. 4.6%, p < .001) and a higher proportion of participants had 10-year risk of CVDs >7.5% (47.7% vs. 25%, p < .001) by the ASCVDS equation.

Fasting glucose, lipid abnormality, and hs CRP

Lipid profiles, fasting glucose, and hs-CRP were not different between participants with subclinical atherosclerosis and normal cIMT. There was no difference in the median hs-CRP between the two groups [1.2 (IQR 0.6–2.6) vs. 1.1 (IQR 0.7–2.6) mg/dL; p = .64], and overall, 67(21.2%) participants had high hs-CRP levels (>3.0 g/dL), Table 3.

Table 3.

Metabolic Profiles and Laboratory Data Among HIV-Infected Patients With and Without Subclinical Atherosclerosis

Characteristics	Total (n = 316)	Normal (N = 231)	Subclinical atherosclerosis (N = 85)	p-value
Total cholesterol, mg/dL	203 (180–236)	202 (177–233)	211 (184–249)	.10
Triglycerides, mg/dL	155 (105–216)	152 (102–209)	166 (111–247)	.10
LDL-cholesterol, mg/dL	124 (101–148)	124 (102–147)	125 (101–149)	.54
HDL-cholesterol, mg/dL	47 (39–56)	47 (39–55)	44 (39–58)	.90
Fasting glucose, mg/dL	93 (85–102)	92 (84–101)	94 (87–105)	.07
Metabolic syndrome, N (%)	131 (41.5)	91 (39.4)	40 (47.1)	.22
Serum creatinine, mg/dL	0.86 (0.76–1.05)	0.84 (0.76–1)	0.91 (0.78–1.12)	.09
eGFR by CKD EPI, mL/min/1.73 m²	88.62 (73.78–98.21)	89.27 (75.8–98.52)	86.18 (71.98–97.48)	.26
<60 mL/min/1.73 m², N (%)	25 (7.91)	17 (7.36)	8 (9.41)	.55
ALT, U/L	28 (21–40)	28 (20–40)	28 (23–39)	.40
Fibrosis-4	1.03 (0.84–1.4)	1.01 (0.83–1.31)	1.2 (0.85–1.53)	.04
≥1.45, N (%)	72 (22.78)	47 (20.35)	25 (29.41)	.09
Insulin (uU/mL), Median (IQR)	7 (4.8–11.2)	6.8 (4.8–10.5)	7.5 (5–12.6)	.22
Hs-CRP (mg/dL), Median (IQR)	1.2 (0.6–2.6)	1.2 (0.6–2.6)	1.1 (0.7–2.6)	.64
hs CRP ≥3 mg/dL	67 (21.2)	50 (21.65)	17 (20.00)

eGFR, estimated glomerular filtration rate; CKD-EPI, chronic kidney disease epidemiology collaboration; hs-CRP, high-sensitivity C-reactive protein; ALT, alanine aminotransferase.

Factors associated with subclinical atherosclerosis

In univariate analysis, traditional risk factors, including age, sex, and ever having smoked, as well as HIV-specific factors, including nadir CD4 cell counts <200 cells/mm³, PI, PI and NNRTI regimen, duration of ART, and lipodystrophy were associated with cIMT >0.9 mm and/or carotid plaques. In the multivariate logistic regression model, only age per 1 year increase [odds ratio (OR) 1.06; 95% confidence interval (CI) 1.003–1.12; p = .04] and CD4 nadir <200 cells/mm³ [OR 1.8; 95%CI 1.02–3.18, p = .04] were significantly associated with cIMT >0.9 mm and carotid plaque (Table 4).

Table 4.

Multivariate Regression Analysis for Factors Correlated with Subclinical Atherosclerosis (cIMT >0.9 mm/Carotid Plaque)

HIV-positive	cIMT		Univariate			Multivariate
HIV-positive	Normal	Subclinical atherosclerosis	OR crude	95%CI	p	OR adjust	95%CI	p
Age, per 1 year increase			1.08	(1.03–1.13)	.002	1.06	(1.003–1.12)	.04
50–59	189 (77.46)	55 (22.54)
60+	42 (58.33)	30 (41.67)
Sex
Male	133 (68.91)	60 (31.09)	1.77	(1.04–3.02)	.04	1.64	(0.71–3.78)	.25
Female	98 (79.67)	25 (20.33)	Ref			Ref
Body mass index, kg/m²
<25	163 (71.81)	64 (28.19)	1.27	(0.72–2.24)	.41
>25	68 (76.40)	21 (23.60)	Ref
Waist/hip ratio
≤1	210 (73.43)	76 (26.57)	Ref
>1	19 (67.86)	9 (32.14)	1.31	(0.57–3.02)	.53
Abdominal obesity (waist circumference >90 cm in men and >80 cm in women
No	137 (70.62)	57 (29.38)	1.40	(0.83–2.36)	.21
Yes	94 (77.05)	28 (22.95)	Ref
Smoking
Never smoke	161 (77.40)	47 (22.60)	Ref			Ref
Ever smoker	70 (64.81)	38 (35.19)	1.86	(1.12–3.10)	.02	1.65	(0.88–3.08)	.12
CD4 Nadir, cells/mm³
≤200	120 (67.04)	59 (32.96)	2.10	(1.24–3.56)	.006	1.80	(1.02–3.18)	.04
>200	111 (81.02)	26 (18.98)	Ref			Ref
Current regimen					.009			.32
NNRTI base only	139 (79.43)	36 (20.57)	Ref			Ref
PI base only	69 (68.32)	32 (31.68)	1.79	(1.03–3.12)		1.45	(0.79–2.66)
Both NNRTI and PI/other	23 (57.50)	17 (42.50)	2.85	(1.38–5.90)		1.68	(0.75–3.76)
Duration on ART, year
<15	94 (81.03)	22 (18.97)	Ref			Ref
≥15	137 (68.50)	63 (31.50)	1.96	(1.13–3.41)	.02	1.72	(0.94–3.16)	.08
Family history CVD
No	117 (72.67)	44 (27.33)	Ref
Yes	110 (72.85)	41 (27.15)	0.99	(0.60–1.63)	.97
Ever used statin drug
No	144 (76.60)	44 (23.40)	Ref			Ref
Yes	87 (67.97)	41 (32.03)	1.54	(0.93–2.55)	.09	1.48	(0.83–2.62)	.18
Current statin use
No	168 (75.00)	56 (25.00)	Ref
Yes	63 (68.48)	29 (31.52)	1.38	(0.81–2.35)	.24
Hypertension
No	145 (76.72)	44 (23.28)	Ref			Ref
Yes	86 (67.72)	41 (32.28)	1.57	(0.95–2.60)	.08	1.47	(0.52–4.19)	.47
Diabetes mellitus	199 (74.81)	67 (25.19)	Ref			Ref
No	32 (64.00)	18 (36.00)	1.67	(0.88–3.17)	.12	1.05	(0.5–2.18)	.91
Yes
Metabolic syndrome
No	140 (75.68)	45 (24.32)	Ref
Yes	91 (69.47)	40 (30.53)	1.37	(0.83–2.26)	.22
Fib 4
<1.45	184 (75.41)	60 (24.59)	Ref			Ref
>1.45	47 (65.28)	25 (34.72)	1.63	(0.93–2.87)	.09	1.20	(0.63–2.31)	.58
Lipodystrophy/lipoatrophy
No	107 (79.85)	27 (20.15)	Ref
Yes	124 (68.13)	58 (31.87)	1.85	(1.10–3.13)	.02
Hs-CRP (mg/dL)
hs CRP <3	181 (72.69)	68 (27.31)	Ref
hs CRP ≥3	50 (74.63)	17 (25.37)	0.91	(0.49–1.68)	.75

In the subgroup analysis, age per 1 year increase [odds ratio (OR) 1.08; 95% confidence interval (CI) 1.02–1.14; p = .01] and CD4 nadir <200 cells/mm³ [OR 2.57; 95%CI 1.49–4.42, p = .001] remained significantly associated with cIMT >0.78 mm and carotid plaques.

Discussion

In this study, we determined the prevalence and factors associated with subclinical atherosclerosis defined as cIMT >0.9 mm/carotid plaques, in 316 well-suppressed, HIV-infected and aging (>50 years) Asian patients. The prevalence of study-defined subclinical atherosclerosis was 26.9%. Of note, 3.8% and 14.9% had cIMT 0.9 mm and >0.78 mm, respectively, and carotid plaques were detected in 77 participants (24.4%). The prevalence of abnormal cIMT in our aging cohort was low compared with other studies in non-Asian HIV-infected populations. A cohort from Spain reported that the prevalence of subclinical atherosclerosis (cIMT >0.8 mm) was 56.1% among 187 HIV-infected patients, many of whom were males, and 80% were cigarette smokers with a mean age of 45 years.²¹ The HERMES cohort from Italy (N = 140) reported a prevalence of subclinical atherosclerosis (cIMT >0.9 mm) of 41.7%; the majority were males (79.2%) with a median age of 40 years and 51.2% were cigarette smokers.¹¹ In a European cohort (75% males, 66% smokers), 32.2% of ART-treated patients had cIMT >1.0 mm.²² The SCOPE cohort from San Francisco, (N = 148, 83% males, mean age of 45 years, 55% current smokers) reported a high prevalence of carotid plaque (45%).¹² Our aging patients had relatively lower rates of subclinical atherosclerosis despite 16.3 years of ART and median age of 54.4 years compared with other studies.^11,12,21,22 This was partly due to a low rate of traditional CVD risk factors, especially smoking: only 12.7% of our cohort were current smokers and 65.8% had never smoked. Nevertheless, the high prevalence of carotid plaques has different clinical implications than cIMT >0.9 mm. Being unstable, the plaques can rupture leading to acute myocardial infarction or stroke.

There is very limited data on the prevalence of subclinical atherosclerosis in Asian populations, only mean cIMT has been reported. In our cohort of HIV-infected patients with median age of 54.4 years, the median cIMT was 0.63 (IQR 0.55–0.72) mm. In a study among hyperlipidemic (N = 216) and healthy Thai participants (n = 86) with mean age of 47.17 years, the mean cIMT were 0.7 and 0.71 mm, respectively.²³ Another study from Thailand among perimenopausal (N = 59) and menopausal women (N = 55) reported mean cIMT of 0.64 and 0.78 mm in study groups, respectively.²⁴ In healthy Indian adults, the average cIMT was 0.67 mm.²⁵ Healthy middle-aged Koreans had mean cIMT of 0.60 mm in men and 0.53 in women.²⁶ Based on these findings, the cIMT was relatively similar among our HIV participants and non-HIV-infected Asian. We have recently reported that cIMT was not different among HIV (N = 60) and non-HIV participants (N = 30), but carotid plaque (N = 6) was found only among the HIV-positive group.²⁷

Several studies have found associations with traditional CVD risk factors and cIMT in people living with HIV.^12,28
–30 However, in our study, advanced age was the only traditional CVD risk associated with high cIMT and carotid plaques. Interestingly, we also found an independent association between low nadir CD4 < 200 cells/mm³, and high cIMT/carotid plaques. This finding is inconsistent with findings from other studies,^11,21,22 and may be related to the high proportion of patients in our study with nadir CD4 counts <200 cells/mm³. Until 2012, Thai National Treatment Guidelines recommended initiating ART when CD4 count was <200 cells/mm³. However, our finding of low CD4 associated with cIMT was in line with the study from Hsue et al. who reported that nadir <200 was associated with progression of cIMT (p = .08).¹² We hypothesize that advanced HIV stage and low nadir CD4 cell counts, are associated with accelerated T cell proliferation, resulting in heightened T cell activation, high levels of inflammatory markers, and systemic inflammation, which likely exacerbate atherogenesis. These immunologic perturbations persist even after several years of successful ART.^12,31,32 Another explanation is that chronic low-grade inflammation contributes to accelerated atherosclerosis.^12,33 In a previous study, low CD4 cell counts were associated with more rapid progression to greater cIMT.¹² Furthermore, several studies in HIV-infected populations have shown an increased risk of CVDs and stroke that persist even after controlling for traditional CVDs risk factors, suggesting contributory effects of nontraditional risk factors (i.e., immune activation).^1,2,34
–36 HIV viral suppression with ART alleviates, but does not normalize immune activation in most HIV-infected patients³⁶; data shows markers of inflammation and monocyte activation decrease with effective ART, but remains higher compared with an HIV-uninfected population.^37
–39 Additionally, markers of endothelial cell activation and dysfunction are also altered in HIV-infected patients. Studies have shown that soluble VCAM-1, a marker of endothelial activation, is higher in HIV infection and it declines with ART, but remains elevated compared with an HIV-uninfected population.^40,41 Therefore, ART initiation at higher CD4 T cell counts may further reduce immune activation and endothelial cell activation, resulting in lower risk of atherosclerosis and CVDs.

High hs-CRP is associated with CVDs among HIV-infected population, especially those who have had a myocardial infarction.⁴² In HIV-infected patients, elevated hs-CRP levels can be from HIV infection or other HIV-related infections, which can be normalized after HIV infection is successfully treated.⁴³ In HIV-infected patients, hs-CRP has been associated with cIMT progression,⁴⁴ CVD risk, and mortality.^45,46 Both hs-CRP and cIMT are associated with all-cause mortality.⁴⁷ In our cohort of well-suppressed HIV-infected patients, hs CRP was not associated with subclinical atherosclerosis, despite the fact that 21% of the participants had hs CRP levels higher than 3 mg/dL. This lack of association is in line with previous reports among ART-treated HIV-infected patients.^14,28,41,48 These results suggest that hs-CRP may not be useful in predicting abnormal cIMT/carotid plaque risk among HIV-infected patients because high CRP level is associated with a higher risk score for coronary heart disease but not for carotid atherosclerosis.⁴⁹

Some limitations of our study should be acknowledged. First, this study was a cross-sectional study so there was no follow-up period to monitor the progression of cIMT and to evaluate the association of cIMT and future CVDs among HIV-infected patients over time. Therefore, further follow-up of this cohort is important. Second, it is difficult to distinguish between stable and vulnerable carotid plaques by B-mode ultrasound, because the measurement is reliable only at the far arterial wall and this does not indicate whether the thickening is attributed to intima or media infiltration/hypertrophy. Third, our study did not have an HIV-negative control population, however, this study was not designed to evaluate the effect of HIV on CVD risk but rather to explore the magnitude of CVD risk among an aging HIV-infected population from Asia. Fourth, we used hs-CRP as a single biomarker of systemic inflammation; other markers such as interleukin-6 and sCD14 have also shown associations with CVDs.³⁶

Conclusion

The prevalence of high cIMT and carotid plaques among virologically well-suppressed, aging HIV-infected patients from Thailand was 26.9%. Subclinical atherosclerosis was associated with advanced age and low nadir CD4 cell count. These data highlight the importance of early ART initiation. Given that approximately a quarter of the patients had carotid plaques, longitudinal studies to evaluate the development of future overt coronary artery disease and stroke are warranted.

Footnotes

Acknowledgments

The authors would like to thank the HIV-infected patients who participated in the study. They would also like to thank the Division of Neurology for performing carotid Doppler ultrasound, and all HIV-NAT staff, especially Pirapon June Ohata, Khuanruan Supakawee, and Jaravee Jamthong.

Author Disclosure Statement

O.P. is a recipient of the Research Chair Grant, the National Science and Technology Development Agency (NSTDA), Thailand. K.R. has received the Senior Research Scholar from Thailand Research Fund (TRF), and he received honoraria or consultation fees from Merck, Roche, Jensen-Cilag, Tibotec, Mylan, and GPO (Governmental Pharmaceutical Organization, Thailand). He also has participated in a company-sponsored speaker's bureau from Abbott, Gilead, Bristol-Myers Squibb, Merck, Roche, Jensen-Cilag, GlaxoSmithKline, and GPO (Governmental Pharmaceutical Organization). A.A. participated in a company-sponsored speaker's bureau from Jensen-Cilag. The rest of the authors declare that they do not have any conflict of interest.

Funding Information

This study was funded by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission (Project Code: NRU59-014-HR) and the Government Research Budget Year 2015 (Project Code: GRB_APS_12_58_30_09). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the article.

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