Cardiovascular Journal of Africa: Vol 23 No 2 (March 2012) - page 53

CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 2, March 2012 AFRICA 107
two-year period for mortality in relation to the level of physical
activity, blood pressure and other risk factors. 21 In this retrospec-
tive cohort of older individuals, serum albumin, diabetes status
and waist/hip ratio were predictors of two-year mortality.
Cohorts of risk factors and trajectories over time or
hard outcomes
Child and adolescent cohorts of CVD and its risk factors: the
‘Mandela’s children’ cohort is the largest and longest ongo-
ing African initiative regarding child and adolescent health. 88-90
The study started in 1989/1990 with 3 273 newborn infants in
Soweto, South Africa.109,110 It was initially designed for a 10-year
follow-up duration and labelled Birth-To-Ten Cohort; this
changed to Birth-To-Twenty when the duration was extended to
20 years. 111 A major contribution to cardiovascular epidemiol-
ogy has been the study of the trajectories of cardiovascular risk
factors in this cohort.88,89
The Ellisras Longitudinal Study (ELS) is an ongoing study
of the growth and health of rural South African children. It was
initially designed as a mixed longitudinal study to investigate
the growth and nutritional status of rural South African children
attending pre-primary and primary school (3–10 years old).95
Initial data collection was limited to anthropometric assessment,
however from the year 2000, data were also collected on blood
pressure variables.93,94,96,97 Baseline data provided information on
the prevalence of risk factors, particularly obesity98 and hyperten-
sion.94 The follow up will provide additional information regard-
ing changing trends with time.
Blood pressure variables and control of hypertension: the Luo
Migration Study in Kenya provided a picture of the changing
pattern of blood pressure variables with time. Some predictors
of these changes were the result of migrating from rural to urban
areas.41,49-51 The dropout rate was very high, with only 35% of the
original sample available for the final evaluation.
The International Collaborative Study on Hypertension in
Blacks (ICSHIB) was a comparative study on hypertension and
TABLE. 2. PROPORTION OF PARTICIPANTS TRACEDAT THE END OF FOLLOW UP19-45
First author
and reference Study country Main focus
Year
published
Ratio final/baseline number of participants and
95% confidence interval
Azura19 Nigeria Adult mortality 2000
0.0 0.5 1.0 1.5
0.95 (0.95–0.96)
Castle20 Zimbabwe Diabetes mellitus 1980 0.95 (0.91–0.99)
Charlton21 South Africa Causes of deaths 1997 0.71 (0.65–0.77)
Cohen22 South Africa Cardiovascular diseases 1978 0.83 (0.77–0.88)
Davidson23 Nigeria Peripartum heart failure 1975 0.53 (0.47–0.60)
Dewar24 South Africa Post-stroke 1990 0.89 (0.84–0.93)
Digenio25 South Africa Cardiac rehabilitation 1992 0.50 (0.46–0.54)
Elamin 27 Sudan Type 1 diabetes 1992 0.95 (0.92–0.97)
Fadahunsi26 Nigeria Rheumatic heart disease 1987 0.58 (0.48–0.68)
Ford28 Nigeria Peripartum heart failure 1998 0.79 (0.74–0.84)
Gill29 South Africa Type 1 diabetes 2005 0.56 (0.45–0.66)
Haitas30 South Africa Familial hypercholesterolaemia 1990 0.98 (0.94–1.02)
Jackson31 South Africa Diabetes mellitus 1974 0.15 (0.11–0.19)
Koegelenberg32 South Africa Infective endocarditis 2003 0.93 (0.88–0.99)
Lang 33 Senegal Hypertension in pregnancy 1993 0.90 (0.88–0.93)
Lester34 Ethiopia Diabetes mellitus 1988 0.60 (0.58–0.62)
Lester35 Ethiopia Diabetes mellitus 1990 0.66 (0.60–0.73)
Luke 36 Nigeria Blood pressure and weight 2006 0.30 (0.27–0.33)
Mayosi37 Cameroon, Nigeria, South Africa Tuberculous pericarditis 2008 0.94 (0.91–0.97)
McLarty38 Tanzania Diabetes mellitus 1990 0.94 (0.93–0.96)
Motala39 South Africa Glucose intolerance 1997 0.68 (0.60–0.76)
Motala45 South Africa Type 2 diabetes 2003 0.23 (0.21–0.24)
Okonofua40 Nigeria Blood pressure in pregnancy 1992 0.63 (0.58–0.68)
Poulter41 Kenya Blood pressure 1990 0.35 (0.31–0.39)
Raimaiya 42 Tanzania Glucose tolerance 1990 0.85 (0.81–0.90)
Reid43 South Africa Mortality 1996 0.99 (0.99–0.99)
Walker44 Gambia Post-stroke 2003 0.96 (0.93–1.00)
0.72 (0.64–0.80)
Random effect: test for heterogeneity: Q = 12259.319 on 26 degrees of freedom (p < 0.001); I2 = 99.8; ratio of number of participants at the
completion vs the number at baseline (boxes) and 95% confidence interval (horizontal lines about the boxes) for 27 studies. When studies were
stratified by date of publication [i.e. ≤ 1990 (11 studies) vs after 1990 (16 studies)], there was similar significant heterogeneity within subgroups
(both p < 0.001), but not between the two subgroups (Q = 0.059, p = 0.808). The results remained unchanged when studies were stratified by dura-
tion of follow up [i.e. < 10 years (18 studies) vs ≥ 10 years (9 studies)], (Q = 0.089, p = 0.765).