Annals of African Medicine

: 2019  |  Volume : 18  |  Issue : 3  |  Page : 158--166

Intima-media thickness of femoral arteries and carotids among an adult hypertensive Nigerian population: A case–control study to assess their use as surrogate markers of atherosclerosis

Mayowa Abimbola Soneye1, Ademola Joseph Adekanmi2, Millicent Olubunmi Obajimi2, Akinyemi Aje3,  
1 Department of Radiology, University College Hospital, Ibadan, Nigeria
2 Department of Radiology, College of Medicine, University of Ibadan, Ibadan, Nigeria
3 Department of Medicine, Cardiology Unit, University College Hospital, Ibadan, Nigeria

Correspondence Address:
Dr. Ademola Joseph Adekanmi
Department of Radiology, College of Medicine, University of Ibadan, Ibadan


Background: Increased intima-media thickness (IMT) is an established and important surrogate marker for atherosclerosis. Intima-media thickening in the femoral arteries occur earlier and reflect the true extent of generalized atherosclerosis better than in the carotids. Aims: To study the ultrasound-detected morphological changes in the common femoral versus carotid artery wall. Patients and Methods: A case-control study design was used, with 61 adult hypertensive as cases and 61 age-, sex- and BMI-matched normotensive as controls. Variables were participants' characteristics, cardiovascular risk factors, and ultrasonographically evaluated IMT of the carotid and femoral arteries. Results: A total of 122 participants were studied. The mean femoral IMT in hypertensives and controls on the right and left was 0.63 ± 0.07mm vs. 0.52 ± 0.06mm [P < 0.0001] and 0.69 ± 0.0 mm vs. 0.55 ± 0.05mm [P < 0.0001]. Also, the mean carotid IMT among hypertensives and controls on the right =0.80 ±0.15mm vs. 0.64 ± 0.06mm [P < 0.0001], and 0.91 ± 0.22mm vs. 0.65 ± 0.06mm [P < 0.0001] on the left. Significant correlation was observed between IMT and age (B = 0.006, P < 0.001 and B = 0.003, P < 0.001), hypertension (B = 0.205, P < 0.001 and B = 0.122, p<0.001), and duration of hypertension (B = 0.02, P < 0.001 and B = 0.006, P = 0.02) the femoral and carotid arteries respectively. Conclusion: The femoral and the carotid artery show similar significantly increased IMT in hypertensive adults. The femoral IMT appears to be a good surrogate marker of atherosclerosis among hypertensive Nigerians.

How to cite this article:
Soneye MA, Adekanmi AJ, Obajimi MO, Aje A. Intima-media thickness of femoral arteries and carotids among an adult hypertensive Nigerian population: A case–control study to assess their use as surrogate markers of atherosclerosis.Ann Afr Med 2019;18:158-166

How to cite this URL:
Soneye MA, Adekanmi AJ, Obajimi MO, Aje A. Intima-media thickness of femoral arteries and carotids among an adult hypertensive Nigerian population: A case–control study to assess their use as surrogate markers of atherosclerosis. Ann Afr Med [serial online] 2019 [cited 2020 Jan 24 ];18:158-166
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Full Text


Increased intima-media thickness (IMT), the first structural change detected in atherosclerosis, is an important surrogate marker in atherosclerosis.[1] IMT assessed in the peripheral large arteries is known to correlate significantly with the presence and progression of atherosclerosis in smaller arteries such as the coronary arteries.[1] IMT measurements have become a proven tool in the selection of high-risk patients and to evaluate the efficacy of therapy.[1],[2] Although advancing age, sex, diabetes, and hypercholesterolemia have been identified as independent risk factors for abnormal IMT or atherosclerosis,[3] hypertension, which leads to complex interactions of increased smooth muscle mass, connective tissues deposition, endothelial dysfunction, and impaired production of endothelium-derived relaxing factors, is a proven and a major cause of arterial wall thickening.[4],[5]

While hypertension remains an important risk factor for the development of generalized atherosclerosis, it has also been implicated as a major risk factor in cardiovascular disease.[6] Hypertension, a chronic medical condition in which blood pressure measurement is at or above a systolic to diastolic blood pressure (DBP) of 140/90 mmHg,[7] is the most common cardiovascular disease in blacks including Nigerians, with a prevalence rate of 10%–48.8%.[8],[9],[10],[11]

Recent reports have shown an increasing prevalence in Africa and beyond, with the developing countries projected to have an enormous share of this rising global burden of hypertension, accounting for about 75% of the world's hypertensive patient population by the year 2025.[12] The increasing prevalence of hypertension in low- and middle-income countries such as Nigeria is also associated with an increase in mortality rates from its complications, including stroke, cardiac failure, and renal diseases.[13]

It is, therefore, imperative to have a simple but precise measurable indicator of atherosclerosis in this group of patients. Among many imaging modalities, B-mode ultrasonographic measurement of IMT has emerged as one of the best methods for evaluating early atherosclerosis, thus helping in the implementation of early treatment.[14]

A recent large population study validated IMT measurement as a valid noninvasive method of monitoring atherosclerotic changes, particularly the progression of IMT and increased plaque burden in the carotid arteries.[15] IMT, an established surrogate marker of generalized atherosclerosis,[3],[16],[17] particularly of the carotids, is an established method in the evaluation of cardiovascular disease morbidity or mortality and for the study of associations with risk factors [18],[19],[20] and coronary or cerebrovascular events.[21],[22],[23],[24],[25],[26]

Although atherosclerosis is a generalized disease process, the extent of atherosclerosis and its effects is known to differ in different vascular beds.[27] In the carotid artery, for example, the intima layer is majorly involved in the intima-media thickening. In the femoral artery, however, the media layer has been documented to be mostly involved in the intima-media thickening process.[4] There is competent and corroborative evidence that cardiovascular risk factors and events are significantly related to an increased IMT in the carotid and the femoral arteries.[18],[19],[20],[21],[22],[23],[24],[25],[26],[28],[29] Treatment of these risk factors was documented to decrease or diminish the progression of the IMT, with consequent reduction in cardiovascular events.[28]

Recent advances in ultrasonography have solidified the place of ultrasonography and positioned IMT and plaques assessment as an important tool in cerebrovascular disease evaluation.[29]

It is worthy of note that despite the wide acceptance of carotid IMT (CIMT), the femoral IMT (FIMT) has been documented as a more representative indicator of generalized atherosclerosis.[30] In addition, the femoral artery shows atherosclerosis earlier and at a more advanced stage than the carotid arteries [31] and yields a better correlation with coronary heart disease and the need for revascularization procedures.[32] While authors have reported the relationship between femoral artery IMT and hypertension in the developed world,[28],[33] there are no published data on this subject in our population to ascertain if FIMT could be a surrogate marker of atherosclerosis in native black hypertensive Nigerians. In this present investigation, we measured and compared the IMT of the femoral arteries with that of carotid arteries, as a marker of atherosclerosis in adult hypertensive Nigerians. We also assessed if the femoral artery IMT may also be used as a marker of atherosclerosis in hypertensive patients in this population.

 Materials and Methods

Study design

This is a prospective case-control study that was carried out in the Department of Medicine (Cardiology unit) and Radiology of a foremost referral Teaching Hospital in South Western Nigeria between January and May 2016. Patients with essential hypertension were enrolled randomly from the Cardiology Clinic of our Institution, and controls were enrolled using the convenience sampling method from the general public and healthy volunteers. This study was approved by the University of Ibadan/University College Hospital Ethical Review Committee.

Inclusion criteria

Adults with only essential hypertension were recruited after the reason for the study and the consent form was adequately explained to the participants, after which the patient either signed or had to thumbprint. To enhance ease of communication, translation was done to the participant in local dialect if there was a need for it.

Exclusion criteria

Those with secondary hypertension, diabetic patients, hypertensives with hyperlipidemia, and hypertensives with previous history of stroke, hypertensives with previous history of coronary heart disease, pregnancy-induced hypertension, unwilling and uncooperative patients, unstable patients, and patients with peripheral arterial disease were all excluded from this study.

Inclusion criteria for controls

Healthy normotensive individuals older than 18 years who were age-, sex-, and body mass index (BMI)-matched with the cases.

Exclusion criteria for controls

Individuals with history of diabetes, unwilling and uncooperative individuals, normotensives with family history of hyperlipidemia, individuals with history of sickle cell disease, individuals with previous history of stroke, and smokers were all excluded from this study.

Clinical evaluation

History of previous cardiovascular disease (stroke, peripheral vascular disease, and cardiac disease), age of the patient, and time since diagnosis of hypertension were obtained and documented. The blood pressure of the patients was measured using an Accuson mercury sphygmomanometer with the patient in seated position after 5 min of rest. Three measurements were taken and the average of the three values recorded for each patient.

The individual height in meters (m) was measured using a stadiometer with the individual standing erect, and the weight in kilogram (kg) was measured using a standing weighing scale that has been zero corrected. The BMI (kg/m 2) was then calculated as weight (kg) ÷ height 2 (m 2). Patients were screened for diabetes mellitus using the fasting blood sugar (normal = 70–110 mg/dl). Fasting lipid profile was used to screen for hyperlipidemia (normal lipid profile – total cholesterol <200 mg/dl, triglycerides <150,200 mg/dl, low-density lipoprotein 80–120 mg/dl, and high-density lipoprotein 35–86 mg/dl).[34],[35]

Ultrasound evaluation

B-mode ultrasonographic measurement of the CIMT and FIMT was done using Ultrasonix SonixSP ultrasound machine with a 7.5–10 MHz linear transducer. The procedure was adequately explained to the patients and consent was obtained. The individuals were in the supine position for the examination. Each patient was well positioned with the neck properly exposed and slightly extended for carotid ultrasound scanning. The head was then rotated 45° away from the side under examination and was supported using a pillow. Ultrasound gel was applied to the neck to reduce tissue-air interface. The common carotid arteries were scanned, and IMT of the far wall [36] of both the arteries were measured after freezing the image. Measurement of IMT was taken from the leading edge of the lumen–intima interface to the opposite media-adventitia interface at 2 cm below the bifurcation of the arteries on both sides.[37],[38] and the IMT measured thrice and the mean recorded [Figure 1]. After the procedure, the rotated neck was returned to the anatomical position, the acoustic coupling gel was completely cleaned off the neck, and the patient made comfortable as much as possible.{Figure 1}

For the B-mode ultrasound measurement of the FIMT, the thigh was adequately exposed and flexed at the hip and knee, and the thigh was externally rotated. The patient was draped and the acoustic gel was applied to the skin of the thigh to minimize the air interface between the probe and skin. The scanning of both common femoral arteries was done, one after the other, just from above the inguinal ligament to its bifurcation into profunda femoris and superficial femoral branches. The IMT was measured twice at the leading edges of lumen–intima interface and of the media-adventitia interface [37],[39],[40] at a point 1–2 cm proximal to the bifurcation of common femoral arteries, and the mean was recorded.[37],[40] This measurement was done at the far wall because of the near wall's gain dependency and unreliability,[41] as shown in [Figure 2].{Figure 2}

Plaques seen within the vessels were documented as a distinct area of localized thickness with an IMT more than 1.5 mm.[41] The flexed thigh and knee were returned to the neutral position after the procedure and the acoustic coupling gel was completely wiped off after the examination. The scanning time on the average, was about 20 minutes.

Data management

The data generated was entered and analyzed using the Statistical Package for the Social Sciences software version 20 (SPSS Inc., Chicago, IL, USA). Frequency tables, percentages, graphs, and means ± standard deviation were used to present the results of the sociodemographic characteristics, anthropometric, and blood pressure measurements of the respondents, after normality test was done. Student's t-test at 95% level of significance was used to measure difference of CIMT and FIMT between categorical variables such as sex (males and females) and study group (cases and controls). Multivariate regression was used to test the correlation between two quantitative variables such as hypertension, age, BMI, and CIMT/FIMT. Chi-square test at 95% level of significance was used to test the association of the presence of carotid and femoral plaques with the study group hypertensive cases and controls. The presence of carotid and femoral plaques were grouped according to the absence or presence of plaques; absent on the right or left side, present on the left, and present right. Two-tailed tests P < 0.05 were considered statistically significant.


A total of 122 adults participated in this study; 61 had hypertension and the remaining 61 were normotensive controls. The individuals had a slight male (50.8%) preponderance in both cases and control groups [Table 1]. The mean age of the hypertensive patients was 51.05 ± 14.69 years with majority (29.5%) within the age of 51–60 years. The average age for control individuals was 51.2 years. There were no statistical differences in gender, occupation, and educational status between the groups with P > 0.05. The distribution of the educational status of the respondents between cases and control showed that the majority of cases (44.3%) and control (45.9%) groups had tertiary education [Table 1].{Table 1}

Among the hypertensive cases, 31/61 (50.8%) had controlled systolic blood pressure (SBP; <140 mmHg and DBP <90 mmHg). Expectedly, there was significant difference in blood pressure between cases and control.

The mean SBP among hypertensive (134.34 ± 15. 02 mmHg) was significantly higher than the mean SBP among the control group (122.80 ± 10.98 mmHg). Similarly, the mean DBP was significantly higher among hypertensives (82.36 ± 9.24 mmHg) than in the controls (77.11 ± 8.76 mmHg). However, there were no significant differences in weight and height. The BMI also showed no significant differences and majority of the cases 43 (70.5%) and controls 40 (65.5%) also had normal weight [Table 2].{Table 2}

Carotid and femoral artery intima-media thickness

The right CIMT (mm) was significantly higher in the hypertensive individuals (0.80 ± 0.15 mm) compared to control group (0.64 ± 0.06 mm), P < 0.001. The mean left CIMT (mm) was also shown to be significantly higher in the hypertensives (0.91 ± 0.22 mm) compared to the control group (0.65 ± 0.06 mm), P < 0.001.

Similarly, the mean right FIMT (mm) was also significantly higher in the hypertensive patients (0.63 ± 0.07 mm) compared to control group (0.52 ± 0.06 mm), P < 0.001. The mean FIMT on the left was also significantly higher in the hypertensive (0.69 ± 0.09 mm) than the control group (0.55 ± 0.05 mm), P < 0.0001 as shown in [Table 3].{Table 3}

There was a progressive increase in both CIMT and FIMT with increasing age in both cases and control. The mean CIMT was significantly different between age groups in the hypertensives (P < 0.001). Among hypertensive patients age 60 years and above, the mean CIMT (0.99 ± 0.16 mm) was significantly higher than in hypertensives who were within 41–50 years (0.75 ± 0.08, P ≤ 0.001) and those not more than 40 years old (0.71 ± 0.07). Similarly, the mean CIMT was significantly higher among hypertensives who were within 51–60 years (0.93 ± 0.16 mm) than in hypertensives who were within 41–50 years (0.75 ± 0.08 mm) and those were than 40 years old and below (0.71 ± 0.07 mm). However, there was no significant difference in the mean CIMT between hypertensives >60 years and those within 51–60 years age group and between hypertensive patients within age group 41–50 years and those not more than 40 years.

Furthermore, the mean FIMT of hypertensive patients who are above 60 years (0.71 ± 0.05 mm) and the mean FIMT of hypertensive patients who are within 51–60 years old (0.66 ± 0.06 mm) both were statistically significantly higher than mean FIMT of hypertensive patients who are above 60 years (0.71 ± 0.05 mm) and the mean FIMT of hypertensive patients who are within 41–50 years (0.64 ± 0.03 mm) and those aged >40 years (0.59 ± 0.05), P < 0.001. A similar trend was also seen in the control. Normotensive individuals who were above 60 years of age had statistically significant higher mean CIMT (0.73 ± 0.06) than in normotensive individuals who were within 51–60 years (0.63 ± 0.04), 41–50 years (0.62 ± 0.02), and individual not more than 40 years of age (0.60 ± 0.02), P < 0.001. However, there was no statistically significant difference in mean CIMT among the other age groups in normotensive individuals. Furthermore, in the femoral arteries, the normotensive individuals who were above 60 years of age had statistically significant higher mean FIMT (0.60 ± 0.05) than in normotensive individuals who were within 51–60 years (0.52 ± 0.03), 41–50 years (0.53 ± 0.04), and individual not more than 40 years of age (0.50 ± 0.02), P < 0.001 [Table 4].{Table 4}

Multivariate analysis showed that age and hypertension were independently associated with CIMT and FIMT. There was an increase in CIMT by 0.006 mm for every year increase in age (95% confidence interval [CI] for B: 0.005; 0.007, P < 0.001). Likewise, there was an increase in CIMT by 0.205 mm in hypertensive patients (95% CI for B: 0.169; 0.241, P < 0.001). There was an increase in FIMT by 0.003 mm with an increase in age (95% CI for B: 0.003; 0.004, P < 0.001). Similarly, there was an increase in FIMT by 0.122 mm in hypertensive patients (95% CI for B: 0.105; 0.138, P < 0.001) [Table 5].{Table 5}

There was an increase in CIMT by 0.02 mm for each year increase in the duration of hypertension (95% CI for B: 0.010; 0.022, P < 0.001) [Figure 3]. Furthermore, FIMT increased by 0.006 mm for each year increase in the duration of hypertension (95% CI for B: 0.003; 0.009, P < 0.001) as shown in [Figure 4].{Figure 3}{Figure 4}

Carotid and femoral plaques

Plaques were seen in the femoral artery in 26.2% (16) of the hypertensive patient and in 18% (11) of the normotensive controls. Femoral plaques were seen more in hypertensive cases than controls, but there was no statistically significant difference(P = 0.276). Similarly, carotid plaques were seen more in hypertensive cases in 26.2% (16) than controls (19.7%; 12 patients), and again, there was no statistically significant association (P = 0.3890) [Table 6].{Table 6}


The mean age of the hypertensive cases in this study is at par with the average age reported in an earlier study in Nigeria.[36] We observed a significantly higher CIMT in hypertensives than in controls, in agreement with the findings of the previous researchers.[21],[36],[42],[43],[44],[45] The CIMT (0.92 ± 0.22 mm) in hypertensives in this study is at par with figures from the developed world [46],[47] and the Jos Nigeria study.[48] This is, however, significantly higher (P < 0.001) than the CIMT measured in hypertensives by Umeh et al.[36] in Ibadan, Nigeria. This may be attributed to continued westernization of our diet and increasing prevalence of hypertension.[8],[9],[10] Another reason from the Jos study [48] may be due to early westernization due to the influx of expatriates into this city with attendant change in, diet, and different prevalence of hypertension.[44]

The left carotid artery has been documented to have higher IMT than the right by Guarini et al. in Italy [46] and Rosfors et al. in Sweden,[49] similar to our findings in this study. The higher CIMT on the left when compared to the right, in both hypertensives and controls, has been attributed to the fact that the left common carotid artery is a direct branch of the arch of the aorta and it is, and therefore, exposed to higher hemodynamic changes.[15]

The gender of the study population also has significant impact on the CIMT. We observed that the CIMT was higher in males than females, in both cases and controls. This observation is also similar to the findings of Ayoola et al.[43] and Gariepy et al.[41] in France. The higher IMT in males may be due to the higher cardiovascular risk factor levels in males.[49]

The age, gender, and BMI of hypertensive patients, among other factors, are known to be associated with the increased IMT. In this study, the age, gender, and BMI were matched between the cases and controls to remove the confounding effect of these variables on IMT. Nonetheless, we found a strong significant correlation between increasing chronological age and CIMT in hypertensives and normotensives (r = 0.72, P < 0.0001), with a remarkable increase from the 51 to 60 age group and above, as reported by previous authors.[43] However, the relative significant increase in IMT among the hypertensives when compared to the control, as suggested by Plavnik et al.,[50] may be due to the additional effect of hypertension on the aging vessels.

In this study, the SBP and DBP were not correlated with CIMT and FIMT as all cases were already on treatment for hypertension. Previous studies where systolic and diastolic pressure were directly correlated with IMT were conducted among new cases, untreated or uncontrolled hypertensive cases, or combination of these cases.[50],[51],[52] However, the diagnosis of hypertension among hypertensive cases already on treatment, in this study, had significant effect on the IMT. Hypertension in this study showed independent correlation with IMT, in accordance with the study of Naseh et al.[48] among treated hypertensive cases. Similar findings between hypertension and CIMT were reported among untreated and uncontrolled hypertensives cases studied by Sasaki et al.[51] and Chironi et al.,[52] respectively. Furthermore, the duration of hypertension showed significant but moderately positive correlation with the CIMT (r = 0.58, P < 0.001). This may be attributed to the increasing damage that hypertension causes on the vessel wall as the duration of the ailment increases.[53]

There is a paucity of information about the femoral artery IMT in the Nigerian population. The observed FIMT values are significantly higher in hypertensive patients than in the normotensive control individuals, where the mean FIMT values were 0.525 mm on the right and 0.54 mm on the left.

In the previous studies, Rietzschel et al.[37] in Belgium reported a higher mean FIMT in males than in females (0.596 mm vs. 0.511 mm) and Kirhmajer et al.,[14] in Spain, observed a higher FIMT in males when compared to females (0.88 mm vs. 0.75 mm). Furthermore, Plavnik et al.[50] in Brazil as well reported a mean of 0.54 mm ± 0.11 mm versus 0.50 mm ± 0.11 mm in males and females, respectively, all in agreement with the findings of a higher FIMT in males when compared to females in this study. The increase in the mean FIMT in males may be due to a similar reason of higher cardiovascular risk factors level in men accounting for higher CIMT values in males.[54]

Furthermore, in the femoral vessels, the age of the hypertensive patients also correlate positively (albeit moderately) and significantly with FIMT in hypertensives in the index study (r = 0.58, P < 0.001). This is in agreement with the findings by Rietzschel et al.[37] This may be attributed to the vascular aging changes and additional effect of hypertension as explained for the carotid arteries IMT increase with age.

Previous studies affirm that age is the strongest determinant of carotid wall thickening, and SBP is considered as a secondary determinant in both hypertensive and normotensives.[55] The duration of hypertensive disease among the cases similarly showed correlation with the FIMT in this study. Similar to our findings in the carotid arteries, hypertension also showed independent correlation with the FIMT.

We observed that plaques were more frequent in the femoral artery when compared with the carotid arteries, in agreement with Wendelhag et al.[15] in Sweden who reported that the femoral artery is exposed to higher hydrostatic pressure and a larger variation of blood pressure than the carotid artery. In the carotid arteries, the plaques were more frequent in the left common carotid artery than in the right common carotid artery, which may be due to the origin of the left common carotid artery which is a direct branch of the aortic arch and therefore exposed to more hemodynamic changes.[15]

A study with a larger sample size in the same locality is recommended to corroborate the findings observed in this study.


The study shows that FIMT was significantly higher in hypertensives than normotensives, just as the CIMT was. Significant differences existed in CIMT and FIMT in patients with longstanding hypertension. FIMT and CIMT are both accurate markers of atherosclerosis in the study population.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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