Populations with COPD demonstrate higher survival in overweight and
obese compared with normal weight; the “obesity paradox.”
Relationships in less severe COPD are unclear, as is the impact of
cardiovascular risk, and few studies include individuals at extremes of
We examined the relationship between body mass index (BMI, defined
as underweight: <20kg/m2, normal: 20-25kg/m2, overweight: 25-
<30kg/m2, obese class I: 30-<35kg/m2, class II: 35-<40kg/m2, class
III: >40kg/m2), morbidity, and mortality in the SUMMIT trial population
(n=16,485), characterized by moderate COPD and heightened
cardiovascular risk with a substantial proportion with class III obesity.
The association between BMI category and time to event was modeled
via proportional hazards (reference normal weight) adjusted for
demographics and cardiorespiratory disease.
Consistent with the paradox, underweight individuals demonstrated
higher mortality (HR 1.31 (95%CI 1.04-1.64)), with lower mortality
among overweight (HR 0.62 (95%CI 0.52-0.73)) and obese class I (HR
0.75 (95%CI 0.62-0.90)). However, mortality increased in obese class
III (HR 1.36 (95%CI 1.00-1.86)). Death was primarily attributable to
Within a large, multinational cohort with moderate COPD and increased
cardiovascular risk, the phenomenon of reduced mortality with obesity
did not persist at BMI>40kg/m2, suggesting that obesity may not remain
protective at the extremes in this population.