Sedentary behavior and mortality in older women: the Women's Health Initiative.
BACKGROUND
Although epidemiologic studies have shown associations between sedentary behavior and mortality, few have focused on older women with adequate minority representation and few have controlled for both physical activity and functional status.


OBJECTIVE
The objective of this study was to determine the relationship between sedentary time and total; cardiovascular disease (CVD); coronary heart disease (CHD); and cancer mortality in a prospective, multiethnic cohort of postmenopausal women.


METHODS
The study population included 92,234 women aged 50-79 years at baseline (1993-1998) who participated in the Women's Health Initiative Observational Study through September 2010. Self-reported sedentary time was assessed by questionnaire and examined in 4 categories (≤4, >4-8, ≥8-11, >11 hours). Mortality risks were examined using Cox proportional hazard models adjusting for confounders. Models were also stratified by age, race/ethnicity, body mass index, physical activity, physical function, and chronic disease to examine possible effect modification. Analyses were conducted in 2012-2013.


RESULTS
The mean follow-up period was 12 years. Compared with women who reported the least sedentary time, women reporting the highest sedentary time had increased risk of all-cause mortality in the multivariate model (HR=1.12, 95% CI=1.05, 1.21). Results comparing the highest versus lowest categories for CVD, CHD, and cancer mortality were as follows: HR=1.13, 95% CI=0.99, 1.29; HR=1.27, 95% CI=1.04, 1.55; and HR=1.21, 95% CI=1.07, 1.37, respectively. For all mortality outcomes, there were significant linear tests for trend.


CONCLUSIONS
There was a linear relationship between greater amounts of sedentary time and mortality risk after controlling for multiple potential confounders.
Division of Nutritional Sciences (Seguin), Cornell University, Ithaca; Fred Hutchinson Cancer Research Center (Seguin, Liu, Wang, LaCroix), Seattle, Washington. Electronic address: rebeccaseguin@cornell.edu.
Rebecca
R
Seguin
Department of Kinesiology and Community Health (Buchner), University of Illinois at Urbana-Champaign, Illinois.
David M
DM
Buchner
Fred Hutchinson Cancer Research Center (Seguin, Liu, Wang, LaCroix), Seattle, Washington.
Jingmin
J
Liu
Department of Family and Preventive Medicine (Allison), University of California San Diego, San Diego.
Matthew
M
Allison
Department of Aging and Geriatric Research (Manini), University of Florida, Gainesville, Florida.
Todd
T
Manini
Fred Hutchinson Cancer Research Center (Seguin, Liu, Wang, LaCroix), Seattle, Washington.
Ching-Yun
CY
Wang
Department of Medicine (Manson), Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
Joann E
JE
Manson
Department of Preventive Medicine (Messina), Stony Brook University School of Medicine, Stony Brook, New York.
Catherine R
CR
Messina
Division of Cardiology (Patel), Department of Medicine, Duke University Medical Center, Durham, North Carolina.
Mahesh J
MJ
Patel
Division of Rheumatology and Clinical Immunology (Moreland), University of Pittsburgh, Pittsburgh, Pennsylvania.
Larry
L
Moreland
Department of Medicine (Stefanick), Stanford Prevention Research Center, Stanford University, Stanford, California.
Marcia L
ML
Stefanick
Fred Hutchinson Cancer Research Center (Seguin, Liu, Wang, LaCroix), Seattle, Washington.
Andrea Z
AZ
Lacroix
D000368:Aged; D015331:Cohort Studies; D015444:Exercise; D005260:Female; D006801:Humans; D008875:Middle Aged; D009026:Mortality; D017698:Postmenopause; D016016:Proportional Hazards Models; D011446:Prospective Studies; D057185:Sedentary Behavior / Q000208:ethnology; D016387:Women's Health / Q000208:ethnology