Obesity Paradox in Patients with Hypertension and Coronary Artery Disease

Obesity Paradox in Patients with Hypertension and Coronary Artery Disease

The American Journal of Medicine
Volume 120, Issue 10, Pages 825-918 (October 2007)


Abstract



Purpose
An obesity paradox, a “paradoxical” decrease in morbidity and mortality with increasing body mass index (BMI), has been shown in patients with heart failure and those undergoing percutaneous coronary intervention. However, whether this phenomenon exists in patients with hypertension and coronary artery disease is not known.

Methods
A total of 22,576 hypertensive patients with coronary artery disease (follow-up 61,835 patient years, mean age 66±9.8 years) were randomized to a verapamil-SR or atenolol strategy. Dose titration and additional drugs (trandolapril and/or hydrochlorothiazide) were added to achieve target blood pressure control according to the Sixth Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure targets. Patients were classified into 5 groups according to baseline BMI: less than 20 kg/m2 (thin), 20 to 25 kg/m2 (normal weight), 25 to 30 kg/m2 (overweight), 30 to 35 kg/m2 (class I obesity), and 35 kg/m2 or more (class II-III obesity). The primary outcome was first occurrence of death, nonfatal myocardial infarction, or nonfatal stroke.

Results
With patients of normal weight (BMI 20 to<25 kg/m2) as the reference group, the risk of primary outcome was lower in the overweight patients (adjusted hazard ratio [HR] 0.77, 95% confidence interval [CI], 0.70-0.86, P<.001), class I obese patients (adjusted HR 0.68, 95% CI, 0.59-0.78, P<.001), and class II to III obese patients (adjusted HR 0.76, 95% CI, 0.65-0.88, P <.001). Class I obese patients had the lowest rate of primary outcome and death despite having smaller blood pressure reduction compared with patients of normal weight at 24 months (−17.5±21.9 mm Hg/−9.8±12.4 mm Hg vs −20.7±23.1 mm Hg /−10.6±12.5 mm Hg, P<.001).

Conclusion
In a population with hypertension and coronary artery disease, overweight and obese patients had a decreased risk of primary outcome compared with patients of normal weight, which was driven primarily by a decreased risk of all-cause mortality. Our results further suggest a protective effect of obesity in patients with known cardiovascular disease in concordance with data in patients with heart failure and those undergoing percutaneous coronary intervention.


Study Limitations
This was a post hoc analysis and thus suffers from the limitations of such studies. Our conclusions should be considered to be hypothesis generating. The INVEST did not collect the waist-to-hip ratio data; therefore, we could not compare BMI with waist-to-hip ratio. Although we did find differences in the primary and secondary outcomes between BMI groups, the baseline characteristics of the BMI categories were not well matched. Although a stepwise model was used, the impact of these baseline differences cannot be ruled out.