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ORIGINAL ARTICLE
Year : 2013  |  Volume : 16  |  Issue : 1  |  Page : 15-18

Prevalence of peripheral artery disease in adult hypertensive patients in Nnewi, Nigeria


Department of Medicine, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Nigeria

Date of Web Publication17-May-2013

Correspondence Address:
Charles U Odenigbo
Department of Medicine, Nnamdi Azikiwe University Teaching Hospital, P.O. Box 910 Nnewi, Anambra State
Nigeria
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DOI: 10.4103/1118-8561.112058

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  Abstract 

Background: Peripheral artery disease (PAD) is usually due to artherosclerosis obliterans of the arteries of the lower limbs. Patients with PAD are at increased risk of mortality from major cardiovascular events, such as myocardial infarction and stroke. This study aims to find the prevalence of peripheral artery disease in adult hypertensive subjects in Nnewi. Materials and Methods : The study was carried out among adult hypertensive subjects in the medical outpatient clinics and the medical wards of the NnamdiAzikiwe University Teaching Hospital, Nnewi.Two-hundred and fifty subjects were recruited between August 2004 and December 2004 for this study. The Rose Intermittent Claudication Questionnaire was administered and the Ankle-Brachial Index (ABI) was assessed with a hand-held Doppler device. PAD was defined as ABI > 0.9.TheEpi info (2002 version) statistical software was used for statistical analysis. Results: The mean age of the study subjects was 58.9±8.9 years. They comprises106 (42.5%) males and 144 (57.6%) females. The overall prevalence of PAD was 24.8% in the total study group. The ratio of asymptomatic to symptomatic subjects was 3.4:1. Hypertensive subjects with diabetes mellitus had a slightly higher prevalence rate (26%), compared to those with hypertension only (24%). The prevalence of PAD was much higher in patients above 55 years (30.7%) than in those below 55 yearsof age (15.5%). Conclusion : Peripheral artery disease is common, though largely asymptomatic in Nigerian hypertensive subjects. More efforts at screening and unmasking subjects are required.

Keywords: Ankle-Brachial Index, diabetes mellitus, Hypertension, Peripheral artery disease


How to cite this article:
Odenigbo CU, Ajaero C, Oguejiofor OC. Prevalence of peripheral artery disease in adult hypertensive patients in Nnewi, Nigeria. Sahel Med J 2013;16:15-8

How to cite this URL:
Odenigbo CU, Ajaero C, Oguejiofor OC. Prevalence of peripheral artery disease in adult hypertensive patients in Nnewi, Nigeria. Sahel Med J [serial online] 2013 [cited 2019 Aug 18];16:15-8. Available from: http://www.smjonline.org/text.asp?2013/16/1/15/112058


  Introduction Top


Cardiovascular disease may be grouped onto a triad consisting ofcerebral,coronary andlower limb circulation. This triad is interwoven. Therefore, clinically evident coronary artery disease (CAD) coexists with peripheral artery disease (PAD) in 40% of cases. [1] CAD is also the major cause of death in patients with PAD. [2] Chronic occlusive PAD is usually the result of atherosclerosis and this makes the assessment of other arms of the triad imperative once it is detected.

In the past, it was reported that atherosclerotic vascular disease is rare in native Africans, however, postmortem studies of Ethiopians between 1982 and1986, surprisingly found that 47% had atherosclerotic lesions of the aorta. [3] Guerchet et al. in a population study in the Central African Republic found a prevalence of 24% for lower extremity PAD in elderly patients using Ankle-Brachial Index (ABI) measurements. [4] Also Tracie C. Collins and co-researchers found a higher prevalence of PAD in African-Americans (22.8%), compared to whites (13.2%) and Hispanics (13.7%), [5] while Amir HS and co-workers found a higher prevalence of PAD among females (23.6%) than males (17.2%), undergoing coronary catheterization. [6] In these groups, independent predictors of PAD included black race, older age, female sex, tobacco use, CAD, diabetes mellitus and triglyceride level.

Hypertension is the most important cardiovascular disease and risk factor all over the world and in Nigeria. [7] It is also a major risk factor for PAD. In Nigeria, hypertension affects 25% of the population above 15 years of age. [8]

The lower limb vessels are far more accessible than the cerebral and coronary vessels, making the assessment of the lower limb vessels a preferred initial choice for the rest of the triad. This however requires an objective, sensitive, and affordable method of assessment. The hand held Doppler device fulfils these criteria and has rarely been used to evaluate the actual prevalence of PAD in Nigerian subjects.

Data on prevalence of PAD in Nigeria are sparse. This study is therefore intended to fill this gap using ankle brachial index (ABI) measurements, which are reliable, non-invasive and by far superior to traditional methods like anamnesis and physical examination. [9]


  Materials and Methods Top


This study was carried out at the NnamdiAzikiwe University Teaching Hospital, Nnewi, Nigeria. Ethical clearance was obtained from the research and ethical committee of the hospital. Informed consent as obtained from the each participant.

Two-hundred and fifty hypertensive patients that presented consecutively at the medical out patients clinics and medical wards were recruited for the study.

Inclusion criteria: Adults aged 18 years and above with hypertensiondefined as sustained elevation of blood pressure above 140/90 mmHg.

Exclusion criteria: Patients who had major limb trauma.

Eighty control subjects were drawn from the general out patients department and hospital workers, who were non-hypertensives and non-diabetics. They were sex and age matched with the study group.

Each subject was administered a questionnaire, detailing the subjects demographics and relevant history of hypertension, diabetes mellitus, and social habits. Then the Rose Intermittent Claudication Questionnaire (RICQ) was administered. The RICQ is the WHO's adopted questionnaire on intermittent claudication. General physical examination was carried out. Blood pressure was measured in both erect and supine positions. The ankle-brachial index (ABI) was then assessed. The mode of calculation of ABI in our study was based on a previous study [10] which showed that better results are obtained when mean systolic blood pressures (SBP) of the posterior tibial and dorsalispedis arteries are used to calculate the ABI for each leg. We therefore calculated ABI for each leg by dividing the mean of both brachial pressures with the mean of each leg's posterior tibialis and dorsalispedis arteries. If one brachial arterial SBP differed from the other by up to 10mmHg, subclavian stenosis was suspected and the higher value used to calculate ABI. In all cases, to enhance sensitivity and specificity, measurements from the leg with the lower ABI was used for diagnosis and PAD was deemed present if ABI was ≤ 0.90.These factors minimized in our study, the impact on results with methodologies that used higher or lower SBP values at the ankle.

Diabetes mellitus was defined as being a known diabetic (currently on treatment with oral hypoglycemic agents and/or insulin); or a newly diagnosed diabetic subject. [11]

Epi info [2002 version] statistical software was used for data entry, validation, and analysis. Microsoft excel 2003 worksheet was also used. Mean, standard deviation, chi-square, z-test, and student t-test were done where appropriate. Variables were retained only if they met P < 0.05 significance level. Mean values and standard deviations were calculated for continuous variables and the means compared, using z test. The chi-square test was used to compare categorical variables. P-value of ≤ 0.05 was taken to indicate statistical significance.


  Results Top


A total of 250 hypertensive subjects made up the study population. One-hundred and six of them (42.6%) were male, while 144 (57.4%) were female, giving a male:female ratio of 1:1.36. One-hundred and fifty of the study population had hypertension only, while 100 had both hypertension and diabetes mellitus. Eighty subjects acted as controls. Of this number, 38 [47.5%] were male, while 42 (52.5%) were female, giving a male: female ratio of 1: 1.11.

Gender did not have any significant impact on the prevalence of PAD. Male subjects (106; 42.4%) had a PAD prevalence of 25.5%, while female subjects (144;57.6%) had a PAD prevalence rate of 24.3% (Z 0.22; P > 0.80).

Level of education was also considered and the findings mirrored that of gender. Subjects with Primary school level education or less (184; 73.6%) had a PAD prevalence rate of 25.5% while those with above primary school level education (66; 26.4%) had a prevalence of 22.7% (Z 0.46; P > 0.6).

Age was the only variable which had a statistically significant impact on the prevalence of PAD in our study. Subjects aged <55years (97; 38.8%) had a PAD prevalence rate of 15.5% while subjects aged ≥55years (153; 61.2%) had a PAD prevalence rate of 30.7% (Z 2.90; P<0.005).

A total number of 36 (14.4%) of our subjects were smokers and had a PAD prevalence rate of 30.6% while 214(85.6%) were non-smokers, with a PAD prevalence of 23.8%. Smoking did not influence the prevalence of PAD in our study subjects(Z 0.93; P>0.40).

Ankle brachial index values >1.3 were not recorded since the diagnostic criteria for ABI in our study was ≤0.9, using mean SBP values.

[Table 1] shows the age distribution of subjects. Mean age of the study group was 58.9 years ± 8.9. Mean age of the control group was 58.8 ± 10.5 years. There is no statistical difference between the mean ages of the study and the control groups [z = 0.31; P > 0.10].
Table 1: Age distribution of subjects

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[Table 2] shows the prevalence of PAD using ABI. Sixty-two [24.8%] of the entire study population had PAD. In the hypertension only sub group, PAD was detected in 36 (24%) of the 150 subjects, while in subjects with both diabetes and hypertension, 26 (26%) out of 100 subjects had PAD. Seven (8.7%) out of the 80 control subjects had PAD. Prevalence of PAD in the study group, compared with the control group was very significant statistically [x 2 = 9.40; P < 0.01]. However, the prevalence of PAD in the different sub groups in the study population (hypertensive only and hypertensive diabetics) was not statistically significant [x 2 = 0.13; P > 0.80].
Table 2: Prevalence of PAD

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[Table 3] shows the comparison of symptomatic and asymptomatic PAD among subjects. The hypertension only sub group had eight (22.2%) of its PAD positive subjects with symptoms of PAD, while the rest were asymptomatic. This was statistically significant [z = 3.34; P> 0.003].
Table 3: Comparison of symptomatic and asymptomatic PAD

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In the diabetic hypertensive subgroup, 6 (23.1%) had symptoms of PAD, while the remaining 20 (76.9%) were asymptomatic. This is also statistically significant [z = 2.75; P < 0.007].

In the control group, 2(28.6%) of those with PAD were symptomatic, while 5 (71.4%) were asymptomatic. The difference between these two groups was not statistically significant [z = 1.13; P > 0.2].


  Discussion Top


This study demonstrated that contrary to widely held view, PAD is relatively common in Nigerians (though largely asymptomatic) in our adult hypertensive subjects.

The overall prevalence of PAD in this study was 24.8%. This figure agrees with the finding of Guerchet and co-workers [4] who found a prevalence of 24% (using ABI measurements) in elderly subjects. Our results also compares favorably with earlier studies in Caucasians by Farkough et al, [12] and Fowkes et al, [13] that showed a prevalence of 18-23% in patients aged 55 years and above. Though this study also used ABI as its diagnostic tool, most of the subjects were not hypertensive.

Our result also agrees with the PARTNERS study, [14] which found a prevalence of 29% in at risk group (i.e. aged 70 years and above or aged 50-69 years with a history of smoking and/or diabetes).

Our results differ significantly from that of Premalatha et al, [15] who found a prevalence of 7.8% in diabetics in non European population of Chennai urban population. This difference may be because of differences in methodology between the twostudies. The study by Premalatha et al. only used Doppler ultrasound on 50% of their study population and diagnosed PAD only if ABI is less than 0.90 (we used ≤ 0.90).

Our study also showed that most of the subjects with PAD were asymptomatic (77.9% in hypetension only group and 76.9% in the diabetic hypertensive subgroup). This is in agreement with findings in the PARTNERS study [14] which reported that classic intermittent claudication was distinctively uncommon (11%) in those with PAD. Also Mc Dermott et al. [9] found that only 33% of patients studied had classic intermittent claudication. Collins et al, [5] in 2003, found a lower prevalence of intermittent claudication in racially diverse subjects in the United States of America.


  Conclusion Top


Peripheral artery disease is common and largely asymptomatic in Nigerian hypertensive subjects. This has obvious negative cardiovascular health implications. We recommend actively evaluation of hypertensives for PAD.

 
  References Top

1.Szilagyi ED, Elliot JP, Smith RF, Reddy DJ, McPharlin M. A thirty year survey of the reconstructive surgical treatment of aortoiliac occlusive disease. J Vasc Surg 1986;3:421-36.  Back to cited text no. 1
    
2.Müller-Bühl U, Diehm C, Sieben U, Berger B, Schuler G, Zimmermann R, et al. Prevalence and risk factors of peripheral arterial occlusive diseases and coronary heart disease. Vasa Suppl 1987;21:1-46.  Back to cited text no. 2
    
3.Maru M. Prevalence of atherosclerosis of the aorta in Ethiopians: A post mortem study. East Afr Med J 1992;69:214-8.  Back to cited text no. 3
    
4.Guerchet M, Aboyans V, Mouaya AM, M'Belesso P, Salazar J, Tabo A, et al. High prevalence of lower extremities peripheral artery disease in Central Africa. Circulation 2009;120:S431.  Back to cited text no. 4
    
5.Collins TC, Petersen NJ, Suarez-Almazor M, Ashton CM. The prevalence of peripheral artery disease in a racially diverse population. Arch Intern Med 2003;163:1469-74.  Back to cited text no. 5
    
6.Rafie AH, Stefanick ML, Sims ST, Phan T, Higgins M, Gabriel A,et al. Sex differences in the prevalence of peripheral artery disease in patients undergoing coronary catheterization. Vasc Med 2010;15:443.   Back to cited text no. 6
    
7.Akinkugbe OO, Nicholson LD, Cruickshank JK. Heart disease in blacks of Africa and the Caribbean. Cardiovasc Clin 1991;21:377-91.  Back to cited text no. 7
    
8.Mabadeje AF 1999 WHO - ISH Guidelines for management of hypertension: Implementation in Africa - the Nigerian experience. Nigeria Guidelines. Clin Exp Hypertens 1999;21:671-81.  Back to cited text no. 8
    
9.McDermott MM, Greenland P, Lui K, Guralnik JM, Celic L, Criqui MH,et al. The ankle brachial index is associated with leg function and physical activity: The walking and leg circulation study. Ann Intern Med 2002;136:873-83.  Back to cited text no. 9
    
10.McDermott MM, Criqui MH, Liu K, Guralnik JM, Greenland P, Martin GJ, et al. Lower ankle/brachial index, as calculated by averaging the dorsalispedis and posterior tibial arterial pressures, and association with leg functioning in peripheral arterial disease. J Vasc Surg 2000;32:1164-71.  Back to cited text no. 10
    
11.Diagnosis and classification of Diabetes mellitus and its complications. Report of WHO part 1 Geneva:World Health Organization; 1999 (WHO / NCD/NCS/1992).  Back to cited text no. 11
    
12.Farkouh MA,Oddone EZ, Simel DL. For the International Cooperative Group for Clinical Examination Research:Improving the clinical examination for a low ankle-brachial index. Int J Angiol 2002;11:41-5.  Back to cited text no. 12
    
13.Fowkes FG, Housley E, Cawood EH, Macintyre CC, Ruckley CV, Prescott RJ. Edinburgh artery study: prevalence of asymptomatic and symptomatic peripheral artery disease in the general population. Int J Epidemiol 1991;20:384-92.  Back to cited text no. 13
    
14.Hirsch AT, Criqui MH, Treat-Jacobson D,Regensteiner JG, Creager MA, Olin JW, et al. Peripheral artery disease detection, awareness and treatment in primary care. JAMA 2001;286:1317-24.  Back to cited text no. 14
    
15.Premalatha G, Shanthirani S, Deepa R, Markovitz J, Mohan V. Prevalence and risk factors of peripheral vascular disease in a selected south Indian population: The Chennai urban population study. Diabetes Care 2000;9:187-91.  Back to cited text no. 15
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3]


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