Cardiovascular Journal of Africa: Vol 28 No 2 (March/April 2017)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 2, March/April 2017

AFRICA

study addressed one of the most fundamental cardiovascular

sequelae of excessive and disproportionate weight. Although the

INTERHEART study investigators cast doubt on the use of BMI

in the context of acute myocardial infarction, obesity, however

defined, was associated with a myriad of conditions, including

hypertension, diabetes mellitus, dyslipidaemia, obstructive sleep

apnoea, gastro-oesophageal reflux, sudden death, stroke, certain

types of cancer, infertility, degenerative joint disease and negative

psychosocial impact.

The Prospective Studies Collaboration addressed the

association of BMI with cause-specific mortality in about 900

000 adults in 57 prospective studies.

These authors concluded

that other anthropometric measures such as WC and WHR

could well add extra information to BMI, and BMI to them, but

that BMI is in itself a strong predictor of overall mortality rate

both above and below the apparent optimum of about 22.5 to

25 kg/m

For screening purposes, it appears that measurements of

WHR provide no advantage over WC alone, are cumbersome

and may be fraught with errors in field situations. Furthermore,

it may not be necessary to measure WC in persons with BMI

35 kg/m

since it adds little value in the predictive power of

disease-risk classification.

Inconsistencies in cut-off values for

WC have potentially undesirable consequences for cardiovascular

risk stratification, disease categorisation and prioritisation of

preventative strategies for obesity. There is therefore a strong

need for validation of these WC cut-off values for Botswana

before they can be used for prediction of incident outcomes such

as cardiovascular diseases or type 2 diabetes mellitus.

Modelling may help to capture the scope and complexity of

the obesity problem in Botswana. Applications of heterogeneous

adaptive pieces of the puzzle that are affected by and/or influence

the overall behaviour of individuals within society may lead to

the development of empirically based public health models.

Agent-based modelling (ABM) represents one such simplified

example.

Using the ABM approach, agents could represent

individuals, their attributes, behaviours and relationships with

other individuals in society. The environment could represent

geographical locations, mobility, domestic settings, market forces

and social networking.

Systematic dynamic modelling (SDM) or perhaps more

appropriately for Botswana, the MicroSimulation model, could

be used to establish temporal and causal associations, if any,

between obesity and related disorders, such as hypertension,

diabetes, abnormal lipids, cardiovascular diseases, cancers,

degenerative musculoskeletal disorders and psychological

afflictions.

The strategy focuses on ‘upstream’ preventive

approaches rather than ‘downstream’ acute and chronic care.

The goal is to enhance the number of safer, healthier people and

prevent others from becoming vulnerable or being afflicted by

obesity and its related complications.

There are, however, several limitations of this study worth

mentioning. Firstly, this was a retrospective analysis of case

notes of a small number of patients seen at a specialised private

medical practice. The finding may not therefore apply to the

general population. Secondly, WC reflects both subcutaneous

and visceral fat and at best represents a crude surrogate

for visceral adiposity. Because women generally have more

subcutaneous fat, there is a potential risk of misclassifying them

as viscerally obese, thereby resulting in overestimation of the

MetS in women. Thirdly, little is known about the full impact of

the obesity epidemic on the health of the community, and failure

to demonstrate statistically significant links between obesity and

existing co-morbidities in this study should not be construed to

suggest benigness of obesity in this population.

Conclusion

This study reiterates the need for ethnic-specific WC cut-off

points for defining central obesity and, by extension, for

diagnosis of the MetS among black Africans. The proposed WC

cut-off values, if validated, will set the pace for larger studies

across sub-Saharan Africa. Variations in WC cut-off values

illustrate the uniqueness of populations.

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