AS286 - OPACH: Objective Physical Activity and Cardiovascular Health in Women Aged 80 and Older

 

Investigator Names and Contact Information

Andrea LaCroix [alacroix@whi.org]

 

Introduction/Intent

 

This study will more precisely define the health benefits of regular physical activity in women aged 80* and older, by using accelerometers to objectively characterize the amounts and patterns of physical activity.  The specific aims are: 

1) To determine the associations between objective measurements of physical activity using an accelerometer, and risk of incident CVD;

2) To compare the magnitude of associations between self-reported and accelerometer measures of physical activity with incident CVD;

3) To conduct a calibration study designed to determine accelerometry thresholds for women ages 80 and older that distinguish sedentary from light activity and light activity from moderate to vigorous activity.

3.1) Using the calibrated cutpoints, associations between intensity of physical activity and incident CVD will be examined.

4)  To determine how level of physical activity influences risk of fall-related injuries and overall risk for any injury. 

The study will enrich the data collection for the 8,000 participants recruited for the WHI home visits (the WHI Long Life Study).  These women will be aged 80 and older and will include all WHIMS participants in that age group at the time of the home visits.  The age limit will be lowered, if necessary, to achieve the recruitment goal of 8000.  Participants will wear an accelerometer for 7 days, complete the CHAMPS and WHI physical activity questionnaires and will be followed for at least 3.5 years to ascertain study outcomes.  A calibration study will be conducted at two clinical centers to assess fitness and using a 400-meter walk and indirect calorimetry.  Injuries will be reported monthly using self-addressed stamped postcards.

Specific Aims

Physical activity levels in older women are inadequately characterized by self-reported questionnaires, even those specifically designed for older adults.  While self-report measures of physical activity have some validity, they lack precision, may reflect over-reporting of activity, and provide only limited information on the details and patterns of physical activity.  Thus, the need to examine objective measurements of physical activity in relation to future cardiovascular events and overall health has been identified as a major gap by both the recently released Program Announcement (PA-0943) entitled "Nutrition and Physical Activity Research to Promote Cardiovascular and Pulmonary Health" and the systematic evidence review done for the 2008 Physical Activity Guidelines for Americans 1, 2.  With the exception of a doubly labeled water (DLW) study with a sample size of 302 older adults 3, all major prospective cohort studies in older adults have measured physical activity by self-report.  By using an accelerometer to collect more precise and complete data on physical activity, cohort studies could address key gaps in knowledge about the health benefits of physical activity.  This study is designed precisely to study objective and self-reported physical activity levels in one of the fastest growing segments of the US population:  women ages 80 and older of diverse race and ethnic backgrounds.

There is strong evidence that regular physical activity reduces the risk of CVD 1.  A recent comparison of interventions to prevent heart disease concluded that promotion of physical activity would have more impact on incidence of CVD than any other intervention 4.  The Women's Health Initiative (WHI) cohort provides a unique and cost-efficient opportunity for advancing science on the health benefits of physical activity.  CVD and other outcomes will continue to be collected on the cohort through at least 2015 and this study will be built upon an extensive infrastructure of exposure and adjudicated outcome data, as well as home visits to be conducted in 2010-2011.  As WHI participants are now in an age range of substantial CVD risk, a sample of 8000 WHI women provides sufficient statistical power to study important details of how physical activity influences CVD risk. 

The long-term objective of this research is to increase understanding of the health benefits and risks of physical activity, so as to improve public health guidelines, and to support the promotion of physical activity.  The primary specific aims are addressed by combining the exposure data collected in this study with the outcome data collected by the WHI parent study:

1)  To determine the associations between objective measurements of physical activity using an accelerometer, and risk of incident CVD in older women participating in WHI.

2)  To compare the magnitude of associations between self-reported and accelerometer measures of physical activity with incident CVD; and to determine if self-report measures of physical activity provide unique information about risk, which is not captured by accelerometer measures.

3) To conduct a calibration study designed to determine accelerometry thresholds for women ages 80 and older that distinguish sedentary from light activity and light activity from moderate to vigorous activity.

3.1) Using the calibrated cutpoints, we will then examine associations between intensity of physical activity and incident CVD.

4)  To determine how level of physical activity influences risk of fall-related injuries and overall risk for any injury.

Although the focus of this application is specifically on cardiovascular disease, the data collection activities necessary to accomplish the above specific aims will also create opportunities to determine the associations between objective measurements of physical activity using an accelerometer and risk of mortality, breast cancer, colon cancer, type 2 diabetes, dementia, cognitive decline and physical disability.  In addition, it will be possible to study associations between objective physical activity and cardiovascular biomarkers measured from biospecimens collected at the home visit (lipids, glucose, insulin, C-reactive protein, creatinine).

 

*NOTE: This study's population is based on the Long Life Study population. The Long Life Study originally planned to enroll women aged 80 years and older. However, consent and participation were lower than initially expected, so the eligible pool was expanded to include women as young as 63 years by 12/1/11.

 

References

1.            Physical Activity Guidelines Advisory Committee report, 2008. To the Secretary of Health and Human Services. Part A: executive summary. Nutr Rev. Feb 2009;67(2):114-120.

2.            Committee PAGA. Physical Activity Guidelines Advisory Committee Report 2008. 2008.

3.            Manini TM, Everhart JE, Patel KV, et al. Daily activity energy expenditure and mortality among older adults. JAMA. Jul 12 2006;296(2):171-179.

4.            Kottke TE, Faith DA, Jordan CO, Pronk NP, Thomas RJ, Capewell S. The comparative effectiveness of heart disease prevention and treatment strategies. Am J Prev Med. Jan 2009;36(1):82-88.