Longitudinal association of body mass index with lung function: The CARDIA Study

Thyagarajan Bharat, Jacobs, Apostol, Smith, Jensen, Crapo, Barr, Lewis, Williams

Description

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, FEV 1 and FEV 1 /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/m 2 experienced 10 year increases of 71 ml in FVC and 60 ml in FEV 1 and neither measure declined through age 38. In contrast, participants with baseline BMI ≥ 26.4 kg/m 2 experienced 10 year decreases of 185 ml in FVC and 64 ml in FEV 1 . FEV 1 /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, FEV 1 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.

Informations

• Publié par: biomed
• Publié le: 01 janvier 2008
• Nombre de lectures: 14
• Langue: English

Extrait

BioMed CentralRespiratory Research
Open AccessResearch
Longitudinal association of body mass index with lung function: The
CARDIA Study
1 2,3 4Bharat Thyagarajan , David R Jacobs Jr* , George G Apostol ,
5 6 6 7Lewis J Smith , Robert L Jensen , Robert O Crapo , R Graham Barr ,
8 8Cora E Lewis and O Dale Williams
1 2Address: Dept of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota, USA, Division of Epidemiology, School
3of Public Health, University of Minnesota, Minneapolis, Minnesota, USA, Institute for Nutrition Research, University of Oslo, Oslo, Norway,
4Abbott Laboratories, Chicago, Illinois (based on work done as a student at Division of, Epidemiology, School of Public Health, University of
5 6Minnesota, Minneapolis, Minnesota, USA, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA, LDS Hospital, Salt
7Lake City, Utah, USA, Division of General Medicine, Department of Medicine and Department of Epidemiology, Columbia University Medical
8Center, New York, New York, USA and Division of Preventive Medicine, Department of Medicine, University of Alabama at, Birmingham,
Birmingham, Alabama, USA
Email: Bharat Thyagarajan - [e-mail]; David R Jacobs* - [e-mail]; George G Apostol - [e-mail];
Lewis J Smith - [e-mail]; Robert L Jensen - [e-mail]; Robert O Crapo - [e-mail]; R
Graham Barr - [e-mail]; Cora E Lewis - [e-mail]; O Dale Williams - [e-mail]
* Corresponding author
Published: 4 April 2008 Received: 20 July 2007
Accepted: 4 April 2008
Respiratory Research 2008, 9:31 doi:10.1186/1465-9921-9-31
This article is available from: http://respiratory-research.com/content/9/1/31
© 2008 Thyagarajan et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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, FEV and FEV /FVC1 1
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.
2 Measurements and Main Results: Participants with baseline BMI < 21.3 kg/m experienced 10
year increases of 71 ml in FVC and 60 ml in FEV and neither measure declined through age 38. In1
2 contrast, participants with baseline BMI ≥ 26.4 kg/m experienced 10 year decreases of 185 ml in
FVC and 64 ml in FEV . FEV /FVC increased with increasing BMI. Weight gain was also associated1 1
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, FEV decreased with1
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.
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(page number not for citation purposes)Respiratory Research 2008, 9:31 http://respiratory-research.com/content/9/1/31
paid health plan in Oakland, CA and from populations inBackground
Many studies find that lung function, as described by the Birmingham, AL, Chicago, IL, and Minneapolis, MN. The
) and/orforced expiratory volume in one second (FEV response rate was approximately 50%, which was consid-1
forced vital capacity (FVC), is inversely correlated with ered acceptable given the required long term commitment
general, pulmonary, and cardiovascular mortality and to the study. The detailed methods, instruments and
qualmorbidity [1-3]. FEV and FVC at the end of life is a func- ity control procedures are described in other published1
tion of lung growth during childhood, peak function in reports [26,27]. In 1985–86 (year 0), 5,115 black and
early adulthood, and subsequent decline related to aging white men and women were recruited for the year 0
examand insults such as cigarette smoking, air pollution, and ination; 4,624 were reexamined in 1987–88 (year 2);
occupational exposures [4-8]. Peak lung function in early 4,352 in 1990–91 (year 5); 4,086 in 1992–93 (year 7);
adulthood is related to gender, race/ethnicity, cigarette and 3,950 in 1995–96 (year 10). At year 0, CARDIA
smoking, exposure to environmental tobacco smoke and included approximately equal numbers of participants
particulate air pollution [7-9]. In addition, lung function who were black and white, men and women, aged 18–24
is decreased by excess body fatness after adjusting for and 25–30, and had more than or less than or equal to
other factors such as age, height, race, sex, asthma and high school education [26,27]. We excluded 58
particismoking status in populations that are at risk for reduced pants who were outside the 18 through 30 age range at
lung function [10-19]. However, in the one study that has year 0, 7 women who were pregnant at baseline, and
anyevaluated the association between BMI and lung function one missing baseline lung function, BMI, physical activity,
in the general population, the median age was 41 years alcohol intake, or smoking, leaving 4,734 participants for
[20]. No study has evaluated the association between BMI analysis. Of these, 4,277 attended year 2, 4,043 attended
and future lung function in young adulthood. year 5, and 3,668 attended year 10. We excluded 147
observations in women who were pregnant at followup
In addition to increases in body weight with age [21], measurement of lung function, since pregnancy might
there are widespread population secular trends of increas- influence both BMI and lung function, but included
ing obesity [22]. In the US, the prevalence of obesity, observations in those same women when not pregnant.
2defined as a body mass index (BMI) >30 kg/m , increased
from 12% in 1992 to 17.9% in 1998 and to 19.8% in Clinic attendance was somewhat higher at the year 10
2000, across all age groups, races, genders and educa- exam among whites (82%) than among blacks (73%).
tional levels [23,24]. A recent paper has shown that the The participants lost to follow-up after years 0, 2, or 5 did
prevalence of obesity has increased from 10.9% in 1996 not differ significantly in most of their year 0
characteristo 22.1% in 2001 in young adults aged 19–26 years [25]. tics when compared with those observed at year 10.
SpeThis obesity epidemic may cause a population-wide wors- cifically, both mean FVC and FEV at year 0 did not differ1
ening of lung function. significantly across those whose last examination
attended was year 0 (n = 203), 2 (n = 232), 5 (n = 221), 7
In the presence of secular and age-related increases in (n = 410), or 10 (n = 3668).
weight and obesity, the goals of the present study were to
quantify age-related changes on FVC, FEV , and the FEV / Measures1 1
FVC ratio according to baseline BMI and BMI changes in Body weight was measured in light clothing to the nearest
0.1 kg with a calibrated balance beam scale, height with-a large, generally healthy, cohort of black men, white
men, black women, and white women followed for 10 out shoes was measured to the nearest 0.5 cm using a
ver2years. Our hypotheses were (1) greater BMI during young tical ruler, and BMI (kg/m ) computed.
adulthood is inversely related to lung function measures
later in life and (2) the effect of change in BMI on future Demographic characteristics, lifestyle habits, and medical
lung function is dependent on the participant's BMI at history were collected by self-report using a questionnaire.
baseline such that an increase in BMI increases lung func- Physical activity was measured using an
interviewertion among those who were thin at baseline, but decreases administered questionnaire [28] concerning the
frelung function among those with high baseline BMI. quency of participation in 13 different activities during
the past 12 months. Because participants were not asked
specifically about duration of physical activity, exactMethods
Participants and Measurements energy expenditure cannot be estimated and the activity is
The data used in these analyses were collected in the Cor- expressed approximately in "Exercise Units" (EU). A score
onary Artery Risk Development In Young Adults (CAR- of 100 EU is roughly equivalent to participation in
activiDIA) study, a multi-center cohort study occurring in the ties such as a vigorous exercise class or bicycling faster
US. The cohorts were recruited from the general popula- th