VOLUME 11 NUMBER 3 • SEPTEMBER 2014
127
SA JOURNAL OF DIABETES & VASCULAR DISEASE
RESEARCH ARTICLE
routine ECG screening. Failure to perform regular ECGs means that
opportunities to improve cardiovascular health in this population
are being missed. Furthermore, our knowledge of the major ECG
abnormalities and their determinants in this environment remains
very limited.
In this study we assessed the distribution of ECG aberrations and
investigated their potential determinants in a group of individuals
with type 2 diabetes who were receiving chronic care in two referral
hospitals in the two largest cities of Cameroon, Central Africa.
Methods
The out-patient sections of the Yaoundé Central Hospital’s diabetes
and endocrine service, and the Douala General Hospital’s (DGH)
internal medicine service and sub-specialties served as settings for
recruitment of participants for this study. The Yaoundé Central
Hospital (YCH) has been described in detail elsewhere.
5,6
The DGH
internal medicine and sub-specialities service has an individualised,
dedicated endocrine section, which is the main referral centre for
endocrine diseases and diabetes in Douala, the second major city
of Cameroon (approximately 2.5 million people). Patients with
diabetes and its complications, residing in Douala and surrounding
regions were the most likely to receive care in our clinic during the
study period.
Overall, the healthcare system in Cameroon is organised into
primary, secondary and tertiary levels. Care at the primary level
is provided by nurses and general practitioners and is essentially
geared towards acute conditions. Secondary-level facilities provide
access to some form of specialist care. Tertiary-level facilities
(including YCH and DGH) serve as a referral hospital for primary-
and secondary-level health facilities, and for routine consultations
and follow up, as in our study.
From January 2010, the Yaoundé health service has had three
endocrinologists and the Douala health service two. Patients with
diabetes who received chronic care in the two study clinics were
required to have an annual evaluation as part of their routine care.
In addition to a clinical consultation, this evaluation included: (1) an
assessment of diabetes control (fasting glucose and haemoglobin
A
1c
levels); (2) an assessment of chronic complications (eyes:
fundoscopy, kidney function: albuminuria, serumurea and creatinine
levels); (3) a cardiovascular work up including an assessment of lipid
profiles (total cholesterol, high-density lipoprotein cholesterol and
triglycerides) and a resting ECG.
Participants in this study were recruited from patients presenting
for these annual evaluations. The study was approved by the
administrative authorities of the two health facilities, and ethical
clearance was obtained from the Cameroon National Ethics
Committee.
Four hundred and twenty individuals with type 2 diabetes
receiving chronic care in the two study facilities were consecutively
enrolled over a two-year period from January 2008 to January
2010. Only the patients’ first consultation during this period was
considered, and no other exclusion criteria were applied. The type
of diabetes was based on the diagnosis of the attending physician.
In addition, patients had to be at least 30 years of age at the time
of their first diagnosis of diabetes.
Blood pressure (mmHg) was measured on the right arm with
the participant in a seated position, after 10 minutes’ rest, with an
Omron
®
MX2 basic electronic device (Omron Healthcare Co, Ltd,
Kyoto, Japan) with the appropriate cuff size. The average of two
measurements recorded five minutes apart was used in this study.
Body weight (kg) was measured in light clothing, using a SECA
®
scale, and height (m) was measured with a standard stadiometer.
The body mass index (BMI) for each patient was calculated as
weight/height
2
(kg/m
2
). The waist circumference (cm) was measured
with a tape measure on the horizontal plane midway between the
lowest rib margin and upper edge of the iliac crest.
A 12-lead resting ECG was done on all subjects using the
Cardi Max Fx-7302
®
. All ECG tracings were centrally interpreted
by the same investigator who is a cardiologist (AD) and did not
know the subjects’ backgrounds. Significant ECG findings such as
ST-segment elevation or depression, T-wave aberrations (inversion
or tall T wave), bundle branch block, left ventricular hypertrophy
(LVH), right and left atrial enlargement, arrhythmias and other
changes were noted.
LVH was defined according to three different criteria:
• Cornell voltage-duration product [(RaVL + SV3) × QRS complex
duration] > 2.623 mm × ms in men and > 1.558.7 mm × ms in
women,
7
• Cornell voltage (SV3 + RaVL > 24 mm in women and 28 mm in
men)
• Sokolov-Lyon index (SV1 + RV5/6 > 35 mm).
Compared with echocardiography, the cut-off values for the Cornell
voltage duration product gave the best sensitivity with a specificity
of 95%.
7
ECG measurements were done with a ruler on the resting ECG
tracings, and were expressed as the average of three determinations
on consecutive QRS complexes. R-wave amplitude in aVL and
S-wave depth in V3 were measured as the distance (mm) from the
isoelectric line of their zenith and nadir, respectively. QRS duration
was measured from the beginning to the end of the QRS complex.
QTc prolongation was defined as a QTc > 460 ms in both men and
women.
A diagnosis of ischaemic heart disease was made based on
the American Heart Association criteria. These criteria include
ECG features of significant ST-segment depression, defined as an
ST-segment depression > 1 mm in more than one lead, and T-wave
inversion. Myocardial infarction was defined as an ST-segment
elevation (convex upwards) > 0.08 s, associated with T-wave
inversion in multiple leads, and reciprocal ST-segment depression
in opposite leads.
Statistical analysis
Data were analysed using SPSS® version 17 for Windows (SPSS,
Chicago, IL). Differences in means and proportions for participants’
characteristics were assessed using analysis of variance and
χ
2
tests
as applicable, and the influence of likely confounders was adjusted
for with logistic regressions models. A probability of
p
< 0.05 was
set as the threshold of statistical significance.
Results
Of the 420 patients recruited, 207 (49%) were men and 250 (56%)
were from the Yaoundé centre. The mean age was 56.7 years and
the median duration of diagnosed diabetes was four years (IQR
25th to 75th percentiles: 1–9).
As expected, anthropometric characteristics were different
between men and women. Diabetes control was also poorer in
men than in women (all
p
< 0.04), otherwise men were similar to
women with regard to many other characteristics, including history
