- Christopher Kabrhel, attending physician 1, assistant professor of surgery 2,
- Raphaëlle Varraso, researcher/epidemiologist34,
- Samuel Z Goldhaber, attending physician 5, professor of medicine2,
- Eric Rimm, associate professor67,
- Carlos A Camargo Jr, attending physician 1, associate professor7
- 1Department of Emergency Medicine, Massachusetts General Hospital, MA, USA
- 2Harvard Medical School, Boston, MA
- 3INSERM, CESP Centre for Research in Epidemiology and Population Health, U1018, Respiratory and Environmental Epidemiology Team, F-94807, Villejuif, France
- 4Université Paris Sud 11, UMRS 1018, F-94807, Villejuif
- 5Department of Medicine, Cardiovascular Division, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
- 6Departments of Epidemiology and Nutrition, Harvard School of Public Health, Boston, MA
- 7Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
- Correspondence to: C Kabrhel, Department of Emergency Medicine, Massachusetts General Hospital, Zero Emerson Place, Suite 3B, Boston, MA 02114
- Accepted 28 April 2011
Objectives To determine the association between physical inactivity (that is, a sedentary lifestyle) and incident idiopathic pulmonary embolism.
Design Prospective cohort study.
Setting Nurses’ Health Study.
Participants 69 950 female nurses who completed biennial questionnaires from 1990 to 2008.
Main outcome measures The primary outcome was idiopathic pulmonary embolism confirmed in medical records. Multivariable Cox proportional hazards models controlled for age, body mass index (BMI), energy intake, smoking, pack years, race, spouse’s educational attainment, parity, menopause, non-aspirin non-steroidal anti-inflammatory drugs, warfarin, multivitamin supplements, hypertension, coronary heart disease, rheumatological disease, and dietary patterns. The primary exposure was physical inactivity, measured in hours of sitting each day. The secondary exposure was physical activity, measured in metabolic equivalents a day.
Results Over the 18 year study period, there were 268 cases of incident idiopathic pulmonary embolism. There was an association between time of sitting and risk of idiopathic pulmonary embolism (41/104 720 v 16/14 565 cases in most inactive v least inactive in combined data; P<0.001 for trend). The risk of pulmonary embolism was more than twofold in women who spent the most time sitting compared with those who spent the least time sitting (multivariable hazard ratio 2.34, 95% confidence interval 1.30 to 4.20). There was no association between physical activity and pulmonary embolism (P=0.53 for trend).
Conclusions Physical inactivity is associated with incident pulmonary embolism in women. Interventions that decrease time sitting could lower the risk of pulmonary embolism.
The Nurses’ Health Study is coordinated at the Channing Laboratory, Brigham and Women’s Hospital, Boston, MA. We acknowledge the dedication and hard work of all of the Nurses’ Health Study staff, especially Gary Chase, Karen Corsano, Betsy Frost-Hawes, Barbara Egan, and of course the nurses themselves.
Contributors: CK conceived the study, obtained funding, collected the data, planned the analysis, drafted and critically revised the manuscript, and approved the final version for publication. RV and CAC conceived the study, obtained funding, planned and performed the statistical analysis, critically revised the manuscript, and approved the final version for publication. SZG and ER conceived the study, obtained funding, critically revised the manuscript, and approved the final version for publication. CK, RV, and CAC are guarantors.
Funding: This study was funded by the National Institute on Aging, National Institutes of Health, Bethesda, MD (R21AG031079, P01CA87969, and R01HL034594). The funding source had no role in design or conduct of the study; collection, management, analysis, or interpretation of the data; preparation, review, or approval of the manuscript.
Competing interest: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: This study was approved by the human research committee of Partners HealthCare.
Data sharing: Requests for access to data, statistical code, questionnaires, and technical processes may be made by contacting the corresponding author at.
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