Research Article: Cardiovascular risk factors in adult general out-patient clinics in Nigeria: a country analysis of the Africa and Middle East Cardiovascular Epidemiological (ACE) study

Date Published: December , 2017

Publisher: Makerere Medical School

Author(s): Geoffrey C Onyemelukwe, Oluwagbenga Ogunfowokan, Amam Mbakwem, A Kayode Alao, Kodjo Soroh, Osahon Omorodion, Paula Abreu.


With globalization and rapid urbanization, demographic and epidemiologic transitions have become important determinants for the emergence of cardiovascular disease (CVD).

To estimate the prevalence of CVD risk factors in adult out-patients attending general practice and non-specialist clinics in urban and rural Nigeria.

As part of the Africa and Middle East Cardiovascular Epidemiological (ACE) study, a cross-sectional epidemiologic study was undertaken for the presence of hypertension, diabetes mellitus, dyslipidemia, obesity, smoking and abdominal obesity in Nigeria.

In total, 303 subjects from 8 out-patient general practice clinics were studied, 184 (60.7%) were female and 119 (39.3%) were male. Mean age was 42.7±13.1 years; 51.8% were aged <45 years; 4% ≥65 years. Over 90% of subjects had ≥1 of 6 selected modifiable cardiovascular risk factors: 138 (45.6%) had 1–2; 65 (21.5%) had 3; 60 (19.8%) had 4; and 11 (3.6%) had 5 concurrent risk factors. Screening identified 206 subjects (68.0%) with dyslipidemia who did not have a prior diagnosis. Cardiovascular risk factors are highly prevalent in Nigerian subjects attending out-patient clinics. Moreover, many subjects were undiagnosed and therefore unaware of their cardiovascular risk status. Opportunistic screening alongside intensive national, multisectoral education or risk factor education is needed, should be scaled up nationwide and rolled out in both urban and rural communities in Nigeria.

Partial Text

Cardiovascular disease (CVD) has emerged in recent decades as a major cause of morbidity and mortality worldwide1–3. An estimated 17-million deaths globally were due to CVD in 2002, and CVD or stroke are projected to become the worldwide leading cause of morbidity and mortality by 20203. This projection applies especially to low and middle-income countries, including Nigeria. Countries like Nigeria are undergoing major demographic transition associated with a progressive ageing population, as well as epidemiologic transition.

The ACE study (July 2011 to April 2012) was a cross-sectional epidemiologic study (described in full elsewhere21). This post-hoc analysis of ACE study data includes Nigerian subjects enrolled from January to February 2012 in general out-patient clinics of the National Hospital Abuja, University of Abuja Teaching Hospital Gwagwalada, Calabar General Hospital Cross River State Calabar, University of Nigeria Teaching Hospital Enugu, Federal Medical Centre Keffi Nassarawa State, General Hospital Akamkpa Cross River State and General Hospital Akpabuyo Cross River State. These sites were chosen specifically to reflect both urban and rural populations21. The Nigerian study sites were part of 94 out-patient general practice clinics in 14 countries (2337 out-patients from 8 African countries; 2041 out-patients from 6 Middle Eastern countries21).

Eligibility criteria were confirmed and demographic data including date of birth/age and gender were captured on a case report form (CRF). Medical history comprising all past/present diseases or syndromes that in the investigator’s judgment were considered to be clinically significant with particular relevance to cardiovascular risk were recorded. Family history of premature coronary heart disease (CHD) was considered as positive if CHD occurred in a male first-degree relative aged <55 years and/or a female first-degree relative aged <65 years. CHD includes history of myocardial infarction, unstable/stable angina, coronary artery procedures (angioplasty or bypass surgery) or evidence of clinically significant myocardial ischemia. The full methodology for the ACE study has been reported elsewhere21. Male or female subjects aged >18 years who signed and dated the informed consent document were included while subjects who presented with any life-threatening disease/condition as well as pregnant women and/or lactating mothers were excluded.

A total of 303 subjects were enrolled into the ACE study from Nigeria, and 301 completed. Participants were a subset of the multi-country ACE sample size which was determined by assuming that >90% of enrolled subjects contribute to the primary analyses, percentage of subjects with dyslipidemia and percentage of subjects with hypertension. The ACE study had a planned total sample size of 4300 subjects which permits the estimation of these percentages to within ± 1.6% with 95% confidence; i.e. the half-width of the 95% confidence interval (CI) will be 1.6 or less21. A minimum of 150 subjects were enrolled per country to obtain a sample size sufficient for exploring the primary endpoint within sub-groups (country, urban vs rural, age, etc.). Enrolment per country had a maximum number of subjects determined by the healthcare infrastructure and ability to provide subjects, based on pre-study feasibility assessment. In the full ACE study and this sub-analysis, every fifth patient seen on a particular day, fulfilling the inclusion and exclusion criteria, was included in the study.

Analyses were primarily descriptive in nature. Binary data were summarized using the percent of subjects with the event and a 95% CI. Continuous data were reported using n, mean, standard deviation, median and range; a 95% CI for the mean was also computed. No interim analyses were planned. All statistical tests were two-sided and conducted at the 0.05 level of significance. P-values ≤0.05 were considered statistically significant. No adjustments for multiple testing were undertaken.

Approval of the ACE study protocol, protocol amendments and informed consent forms were obtained from the IRB/IEC as reported elsewhere21. The study was conducted in accordance with the Declaration of Helsinki on Ethical Principles for Medical Research Involving Human Subjects, adopted by the General Assembly of the World Medical Association (1996).

Primary prevention, early detection and prompt, effective control as well as health promotion strategies are critical in the attempt to reverse the global burden of CVD27,28. This cross-sectional study of Nigerian out-patients revealed a low prevalence of smoking (2.3%), but it importantly highlights the high prevalence of hypertension (43.9%) and the more alarmingly, the high prevalence of dyslipidemia (71.1%), most frequently associated with low HDL-C in almost 39% of patients. Furthermore, we report that obesity, defined either by BMI (24.4%) or in particular by abdominal circumference (63.7%) was also highly prevalent, possibly suggesting poor nutrition or an inadequate exercise culture among these Nigerian out-patients. Reorganization of the Nigerian food-pyramid, together with a national exercise incentive program may aid reducing the prevalence of obesity, targeting everywhere from homes to schools. Obesity and being overweight have been documented to start early in Nigerian pre-school and school children30,31, thus prompting the extension of control measures to age groups below those of the adult population in this study. Such a radical plan would need to be implemented by a multisectoral, multidisciplinary team involving communities, for example the Nigerian Labour Congress, women’s organizations or religious groups29,30.

Cardiovascular risk factors are highly prevalent in adults attending general out-patient clinics in Nigeria, many of whom were undiagnosed and therefore unaware of their cardiovascular risk status prior to screening. We recommend that opportunistic cardiovascular disease risk factor screening alongside intensive national, multisectoral cardiovascular education needs to be implemented, scaled up nationwide, and rolled out in both urban and rural communities in Nigeria.




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