Longitudinal association of body mass index with lung function: the CARDIA study

Abstract

Background: Lung function at the end of life depends on its peak and subsequent decline. Because obesity is epidemic in young adulthood, we quantified age-related changes in lung function relative to body mass index (BMI).

Methods: The Coronary Artery Risk Development in Young Adults (CARDIA) study in 1985-86 (year 0) recruited 5,115 black and white men and women, aged 18-30. Spirometry testing was conducted at years 0, 2, 5 and 10. We estimated 10 year change in FVC, FEV1 and FEV1/FVC according to baseline BMI and change in BMI within birth cohorts with initial average ages 20, 24, and 28 years, controlling for race, sex, smoking, asthma, physical activity, and alcohol consumption.

Measurements and main results: Participants with baseline BMI < 21.3 kg/m2 experienced 10 year increases of 71 ml in FVC and 60 ml in FEV1 and neither measure declined through age 38. In contrast, participants with baseline BMI > or = 26.4 kg/m2 experienced 10 year decreases of 185 ml in FVC and 64 ml in FEV1. FEV1/FVC increased with increasing BMI. Weight gain was also associated with lung function. Those who gained the most weight over 10 years had the largest decrease in FVC, but FVC increased with weight gain in those initially thinnest. In contrast, FEV1 decreased with increasing weight gain in all participants, with maximum decline in obese individuals who gained the most weight during the study.

Conclusion: Among healthy young adults, increasing BMI in the initially thin participants was associated with increasing then stable lung function through age 38, but there were substantial lung function losses with higher and increasing fatness. These results suggest that the obesity epidemic threatens the lung health of the general population.

Figure 1

Presence of overweight and obesity according to NHLBI cutpoints (overweight body mass index (BMI) 25–29.9 kg/m², obese BMI ≥ 30 kg/m²), by quartile of baseline BMI; and progression over 10 years.

Figure 2

FVC in year 0 BMI quartiles across three birth cohorts: 18–21 years, 22–26 years, and 27–30 years at baseline, based on repeated measures linear regression analysis and adjusted for race, sex, current age, smoking status at year 0, asthma status, time, physical activity score at year 0, and alcohol consumption at year 0. The slope of FVC across time becomes increasingly negative with increasing year 0 BMI (p trend < 0.0001).

Figure 3

FEV₁ in year 0 BMI quartiles across three birth cohorts: 18–21 years, 22–26 years, and 27–30 years at baseline, based on repeated measures linear regression analysis and adjusted for race, sex, current age, smoking status at year 0, asthma status, time, physical activity score at year 0, and alcohol consumption at year 0. The slope of FEV₁ across time becomes increasingly negative with increasing year 0 BMI (p trend < 0.0001).

Figure 4

FEV₁/FVC in year 0 BMI quartiles across three birth cohorts: 18–21 years, 22–26 years, and 27–30 years at baseline, based on repeated measures linear regression analysis and adjusted for race, sex, current age, smoking status at year 0, asthma status, time, physical activity score at year 0, and alcohol consumption at year 0. The slope of FEV₁/FVC across time becomes increasingly positive with increasing year 0 BMI (p trend < 0.0001).