The obesity-mortality paradox in elderly patients with angiographic coronary artery disease: a report from the ET-CHD registry

Abstract

Background The body mass index (BMI)-mortality paradox has been well known in patients with obstructive coronary artery disease (CAD). However, this phenomenon has rarely been described among elderly patients over a 5-year follow-up.

Methods We studied a cohort of 722 elderly patients (age ≥ 65 years) with angiographic CAD from the ET-CHD registry during 1997-2003 in eastern Taiwan. To evaluate the BMI eff ect on mortality, the elderly subjects were categorized into 5 groups by BMI (kg/m2): underweight and normal-low weight (< 21), normal-high weight (21-23.9) overweight (24-26.9), mild obesity (27-29.9) and moderate/severe obesity (≥ 30). At a maximal 10-year follow-up, cardiac and all-cause deaths were the primary end points.

Results After multivariate analysis, patients from the category of underweight and normal-low weight in reference to those from the normal-high weight category had a signifi cantly higher risk of cardiac and all-cause mortality (hazard ratio (HR): 1.68 (95% CI: 1.04-2.70) and 2.02 (95% CI: 1.42-2.87), respectively) following a median of 5.4 years. Obese elderly patients tended to have the lowest risk of all-cause death across all the study BMI categories in the early stage. However, after 5 years, mortality increased in the obese patients surviving beyond 5 years, and was higher than that in overweight patients.

Conclusions The obesity-mortality paradox was present in elderly patients with angiographic CAD in Taiwan and the risk of death was signifi cantly higher in those with a BMI < 21 kg/m2. However, a J-shaped relationship between mortality and BMI developed after 5 years of follow-up.

Key Words:

• Obesity-mortality paradox
• angiographic coronary artery disease
• elderly patients
• duration of observation