Public health

Obesity paradox is alive and well in secondary prevention

Saturday, 10 Aug 2019


Weight loss in obese people who have had a cardiovascular event does not prevent recurrent events and in some cases may even increase risk, CSANZ delegates have heard. 

Associate Professor David Colquhoun from the University of Queensland and Wesley and Greenslopes Hospitals in Brisbane told delegates attending a clinical, surgical and prevention session that obesity was a global epidemic, with recent data from the WHO showing that worldwide obesity had almost tripled since 1975. 

He noted that an increasing number of weight loss medications had become available as an adjunct treatment of obesity along with recommendations for diet and exercise. 

However, trials had generally shown that losing weight did not have effect on mortality or cardiovascular outcomes and in some cases, had a protective effect. For example, one study found that obese patients with heart failure had better outcomes than their lighter counterparts.

And in the British Heart study weight loss in obese patients decreased coronary heart disease by 30 per cent but later follow up showed that a 4 per cent weight loss upped mortality due to cardiovascular disease by 38 per cent. 

A comparison of cardiovascular outcomes studies for non-GLP-1 anti-obesity medications also painted a grim picture, Prof. Colquhoun told the audience. 

For example, the LOOK AHEAD trial assessed lifestyle measures plus orlistat in people with diabetes but was terminated early due to futility. 

“All these programs that governments love, the hundreds of millions of dollars, billions spent around the world to prevent cardiovascular disease, the only decent trial we had terminated due to futility so governments of course spend money not necessarily for efficacy but for political reasons,” Prof. Colquhoun said. 

Equally disappointing was the SCOUT trial, of which Prof. Colquhoun’s centre was the lead Australian site. 

“There was blood, sweat and tears for this one, it looked really good until the last moment and it fell over… the drug was withdrawn [sibutramine] after because of increased cardiovascular events so that was incredibly disappointing,” he lamented. 

The CRESCENDO, LIGHT and CONVENE studies were also terminated early due to lack of effect.

In stark contrast, treatments such as lipid and blood pressure lowering, or medical treatment of diabetes and depression had proven benefit. Lowering systolic blood pressure by 10mm/Hg conferred a 10 to 20 per cent decreased risk of cardiovascular disease.

Obesity is definitely a marker of increased risk, it is possibly a risk factor but we need more trials,  but we can’t say that lowering weight definitely decreases cardiovascular events … the obesity paradox for secondary prevention, no question about it is alive and well, ” Prof. Colquhoun told the audience.

” [with weight loss] blood sugar drops, blood pressure improves, weight loss occurs and while you may look better at the beach it doesn’t mean you’ve got a better heart risk reduction.

“With our limited resources we shouldn’t be focusing and wasting money on treatments that are ineffective,” he added.

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