Associations of accelerometer-measured physical activity and physical activity-related cancer incidence in older women: results from the WHI OPACH Study

Background: We examined the associations between accelerometry-measured physical activity (PA) and incidence of 13 cancers among a cohort of postmenopausal women. Methods: In this prospective study, 6382 women wore ActiGraph GT3X+ accelerometers at the hip for up to 7 days during 2012–2013, and were followed over a median of 4.7 years for diagnosis of 13 invasive cancers. Calibrated intensity cut points were used to define minutes per day of total, light and moderate-to-vigorous PA. We used multivariable Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for tertiles, and one-standard deviation (SD) unit increments of PA exposures in relation to cancer incidence. We examined effect measure modification by age, race/ethnicity, body mass index and smoking history. Results: The highest (vs. lowest) tertiles of total, light and moderate-to-vigorous PA were associated with covariate-adjusted HRs of 0.72 (95% CI = 0.53–0.97), 0.81 (95% CI = 0.60–1.09) and 0.66 (95% CI = 0.48–0.91), respectively. In age-stratified analyses, HRs for total PA were lower among women <80 years (HRper one-SD = 0.75, 95% CI = 0.63–0.90) than among women ≥80 years (HRper one-SD = 0.99, 95% CI = 0.82–1.18) (PInteraction = 0.03). Race/ethnicity, BMI and smoking did not strongly modify these associations. Conclusions: Engaging in physical activity may play a beneficial role in the prevention of certain cancers in older women

Accelerometer-measured physical activity and sedentary behavior in relation to all-cause mortality: The women's health study

Physical inactivity is estimated to cause as many deaths globally each year as smoking. Current guidelines recommend ≥150 min/wk of moderate-intensity aerobic physical activity (PA) and muscle-strengthening exercises on ≥2 d/wk. These guidelines are based primarily on studies using self-reported moderate-to vigorous-intensity PA (MVPA). Technological developments now enable device assessments of light-intensity PA (LPA) and sedentary behavior, and well-designed studies with such assessments that investigate clinical outcomes are needed for updating current guidelines. Here, we present data from the WHS (Women’s Health Study). (The data, analytical methods, and study materials will not be made available to other researchers for purposes of reproducing the results or replicating the procedure.

Hot Deck Multiple Imputation for Handling Missing Accelerometer Data

Missing data due to non-wear are common in accelerometer studies measuring physical activity and sedentary behavior. Accelerometer outputs are high-dimensional time-series data that are episodic and often highly skewed, presenting unique challenges for handling missing data. Common methods for missing accelerometry either are ad-hoc, require restrictive parametric assumptions, or do not appropriately impute bouts. This study developed a flexible hot-deck multiple imputation (MI; i.e., “replacing” missing data with observed values) procedure to handle missing accelerometry. For each missing segment of accelerometry, “donor pools” contained observed segments from either the same or different participants, and ten imputed segments were randomly drawn from the donor pool according to selection weights, where the donor pool and selection weight depended on variables associated with non-wear and/or accelerometer-based measures. A simulation study of 2550 women compared hot deck MI to two standard methods in the field: available case (AC) analysis (i.e., analyzing all observed accelerometry with no restriction on wear time or number of days) and complete case (CC) analysis (i.e., analyzing only participants that wore the accelerometer for ≥ 10 h for 4–7 days). This was repeated using accelerometry from the entire 24-h day and daytime (10am–8pm) only, and data were missing at random. For the entire 24-h day, MI produced less bias and better 95% confidence interval (CI) coverage than AC and CC. For the daytime only, MI produced less bias and better 95% CI coverage than AC; CC produced similar bias and 95% CI coverage, but longer 95% CIs than MI

The relationship of accelerometer-assessed standing time with and without ambulation and mortality: The WHI OPACH study

Background: Self-reported time spent standing has been associated with lower risk of mortality. No previous studies have examined this association using device-measured standing. Method: This was a prospective cohort study of 5878 older (median age = 80 years), racial/ethnically diverse, community-dwelling women in the WHI Objective Physical Activity and Cardiovascular Health Study (OPACH). Women wore accelerometers for 1 week and were followed for mortality. The study applied previously validated machine learning algorithms to ActiGraph GT3X+ accelerometer data to separately measure time spent standing with and without ambulation. Cox proportional hazards models were used to estimate mortality risk adjusting for potential confounders. Effect modification by age, body mass index, moderate-to-vigorous physical activity, sedentary time, physical functioning, and race/ethnicity was evaluated. Results: There were 691 deaths during 26 649 person-years of follow-up through March 31, 2018 (mean follow-up = 4.8 years). In fully adjusted models, all-cause mortality risk was lower among those with more standing without ambulation (quartile [Q] 4 vs Q1 HR = 0.63; 95% CI = 0.49-0.81, p-trend =.003) and more standing with ambulation (Q4 vs Q1 HR = 0.50; 95% CI = 0.35-0.71, p-trend <.001). Associations of standing with ambulation and mortality were stronger among women with above-median sedentary time (HR = 0.51; 95% CI = 0.38-0.68) compared to women with below-median sedentary time (HR = 0.80; 95% CI = 0.59-1.07; p-interaction =.02). Conclusions: In this prospective study among older women, higher levels of accelerometer-measured standing were associated with lower risks of all-cause mortality. Standing is an achievable approach to interrupting prolonged sedentary time, and if not contraindicated, is a safe and feasible behavior that appears to benefit health in older ages

Calibrating physical activity intensity for hip-worn accelerometry in women age 60 to 91 years: The Women's Health Initiative OPACH Calibration Study

Objective: We conducted a laboratory-based calibration study to determine relevant cutpoints for a hip-worn accelerometer among women ≥. 60. years, considering both type and filtering of counts. Methods: Two hundred women wore an ActiGraph GT3X. + accelerometer on their hip while performing eight laboratory-based activities. Oxygen uptake was measured using an Oxycon portable calorimeter. Accelerometer data were analyzed in 15-second epochs for both normal and low frequency extension (LFE) filters. Receiver operating characteristic (ROC) curve analyses were used to calculate cutpoints for sedentary, light (low and high), and moderate to vigorous physical activity (MVPA) using the vertical axis and vector magnitude (VM) counts. Results: Mean age was 75.5. years (standard deviation 7.7). The Spearman correlation between oxygen uptake and accelerometry ranged from 0.77 to 0.85 for the normal and LFE filters and for both the vertical axis and VM. The area under the ROC curve was generally higher for VM compared to the vertical axis, and higher for cutpoints distinguishing MVPA compared to sedentary and light low activities. The VM better discriminated sedentary from light low activities compared to the vertical axis. The area under the ROC curves were better for the LFE filter compared to the normal filter for the vertical axis counts, but no meaningful differences were found by filter type for VM counts. Conclusion: The cutpoints derived for this study among women ≥. 60. years can be applied to ongoing epidemiologic studies to define a range of physical activity intensities

Accelerometer-Measured Sedentary Patterns are Associated with Incident Falls in Older Women

Background/Objective: Falls cause significant problems for older adults. Sedentary time is associated with lower physical function and could increase the risk for falls. Design: Prospective study. Setting: Sites across the United States. Participants: Older women (N = 5,545, mean age 79 years) from the Women's Health Initiative Objective Physical Activity and Cardiovascular Health study. Measurements: Accelerometers worn at the hip for up to 1 week collected measures of daily sedentary time and the mean sedentary bout duration, a commonly used metric for sedentary accumulation patterns. For up to 13 months after accelerometer wear, women reported daily whether they had fallen on monthly calendars. Results: In fully adjusted models, the incident rate ratios (95% confidence interval) for quartiles 1 (lowest), 2, 3, and 4 of sedentary time respectively were 1.0 (ref.), 1.07 (0.93–1.24), 1.07 (0.91–1.25), and 1.14 (0.96–1.35; P-trend =.65) and for mean sedentary bout duration was 1.0 (ref.), 1.05 (0.92–1.21), 1.02 (0.88–1.17), and 1.17 (1.01–1.37; P-trend =.01), respectively. Women with a history of two or more falls had stronger associations between sedentary time and falls incidence compared with women with a history of no or one fall (P for interaction =.046). Conclusions: Older women in the highest quartile of mean sedentary bout duration had a significantly increased risk of falling. Women with a history of frequent falling may be at higher risk for falling if they have high sedentary time. Interventions testing whether shortening total sedentary time and/or sedentary bouts lowers fall risk are needed to confirm these observational findings

Sedentary Behavior and Cardiovascular Disease in Older Women: The OPACH Study

Background: Evidence that higher sedentary time is associated with higher risk for cardiovascular disease (CVD) is based mainly on self-reported measures. Few studies have examined whether patterns of sedentary time are associated with higher risk for CVD. Methods: Women from the OPACH Study (Objective Physical Activity and Cardiovascular Health; n=5638, aged 63-97 years, mean age 79±7 years) with no history of myocardial infarction or stroke wore accelerometers for 4 to 7 days and were followed up for up to 4.9 years for CVD events. Average daily sedentary time and mean sedentary bout duration were the exposures of interest. Cox regression models were used to estimate hazard ratios (HRs) and 95% CIs for CVD using models adjusted for covariates and subsequently adjusted for potential mediators (body mass index, diabetes mellitus, hypertension, and CVD risk biomarkers [fasting glucose, high-density lipoprotein, triglycerides, and systolic blood pressure]). Restricted cubic spline regression characterized dose-response relationships. Results: There were 545 CVD events during 19 350 person-years. With adjustment for covariates, women in the highest (≈11 h/d or more) versus the lowest (≈9 h/d or less) quartile of sedentary time had higher risk for CVD (HR, 1.62; 95% CI, 1.21-2.17; P trend 0.05, each). Women jointly classified as having both high sedentary time and long bout durations had significantly higher risk for CVD (HR, 1.34; 95% CI, 1.08-1.65) than women with low sedentary time and short bout duration. All analyses were repeated for incident coronary heart disease (myocardial infarction or CVD death), and associations were similar, with notably stronger HRs. Conclusions: Both high sedentary time and long mean bout durations were associated in a dose-response manner with increased CVD risk in older women, which suggests that efforts to reduce CVD burden might benefit from addressing either or both components of sedentary behavior

Sedentary Behavior and Diabetes Risk Among Women Over the Age of 65 Years: The OPACH Study

OBJECTIVE: To evaluate whether sedentary time (ST) and/or sedentary behavior patterns are related to incident diabetes in the U.S.'s oldest age-groups. RESEARCH DESIGN AND METHODS: Women without physician-diagnosed diabetes (n = 4,839, mean ± SD age = 79 ± 7 years) wore accelerometers for ≥4 days and were followed up to 6 years for self-reported newly diagnosed diabetes requiring treatment with medications. Hazard ratios (HRs) for incident diabetes were estimated across quartiles of accelerometer-measured ST and mean bout duration with use of Cox proportional hazards models. We conducted isotemporal substitution analyses using Cox regression and tested associations with risk for diabetes after statistically replacing ST with light physical activity (PA) or moderate-to-vigorous PA (MVPA) and after replacing light PA with MVPA. RESULTS: During 20,949 person-years, 342 diabetes cases were identified. Women in ST quartile (Q)2, Q3, and Q4 (vs. Q1) had incident diabetes HR 1.20 (95% CI 0.87-1.65), 1.33 (0.97-1.82), and 1.21 (0.86-1.70); Ptrend = 0.04. Respective HRs following additional adjustment for BMI and MVPA were 1.04 (95% CI 0.74-1.47), 1.04 (0.72-1.50), and 0.85 (0.56-1.29); Ptrend = 0.90. Fully adjusted isotemporal substitution results indicated that each 30 min of ST replaced with MVPA (but not light PA) was associated with 15% lower risk for diabetes (HR 0.85 [95% CI 0.75-0.96]; P = 0.01); the HR for replacing 30 min of light PA with MVPA was 0.85 (95% CI 0.73-0.98); P = 0.03. Mean bout duration was not associated with incident diabetes. CONCLUSIONS: Statistically replacing ST or light PA with MVPA was associated with lower diabetes risk in older women. While reducing ST is important for several health outcomes, results indicate that to reduce diabetes risk among older adults, the primary public health focus should be on increasing MVPA

Association of Light Physical Activity Measured by Accelerometry and Incidence of Coronary Heart Disease and Cardiovascular Disease in Older Women

Importance: To our knowledge, no studies have examined light physical activity (PA) measured by accelerometry and heart disease in older women. Objective: To investigate whether higher levels of light PA were associated with reduced risks of coronary heart disease (CHD) or cardiovascular disease (CVD) in older women. Design, Setting, and Participants: Prospective cohort study of older women from baseline (March 2012 to April 2014) through February 28, 2017, for up to 4.91 years. The setting was community-dwelling participants from the Women's Health Initiative. Participants were ambulatory women with no history of myocardial infarction or stroke. Exposures: Data from accelerometers worn for a requested 7 days were used to measure light PA. Main Outcomes and Measures: Cox proportional hazards regression models estimated hazard ratios (HRs) and 95% CIs for physician-adjudicated CHD and CVD events across light PA quartiles adjusting for possible confounders. Light PA was also analyzed as a continuous variable with and without adjustment for moderate to vigorous PA (MVPA). Results: Among 5861 women (mean [SD] age, 78.5 [6.7] years), 143 CHD events and 570 CVD events were observed. The HRs for CHD in the highest vs lowest quartiles of light PA were 0.42 (95% CI, 0.25-0.70; P for trend <.001) adjusted for age and race/ethnicity and 0.58 (95% CI, 0.34-0.99; P for trend = .004) after additional adjustment for education, current smoking, alcohol consumption, physical functioning, comorbidity, and self-rated health. Corresponding HRs for CVD in the highest vs lowest quartiles of light PA were 0.63 (95% CI, 0.49-0.81; P for trend <.001) and 0.78 (95% CI, 0.60-1.00; P for trend = .004). The HRs for a 1-hour/day increment in light PA after additional adjustment for MVPA were 0.86 (95% CI, 0.73-1.00; P for trend = .05) for CHD and 0.92 (95% CI, 0.85-0.99; P for trend = .03) for CVD. Conclusions and Relevance: The present findings support the conclusion that all movement counts for the prevention of CHD and CVD in older women. Large, pragmatic randomized trials are needed to test whether increasing light PA among older women reduces cardiovascular risk

Accelerometer-Measured Moderate to Vigorous Physical Activity and Incidence Rates of Falls in Older Women

Objectives: To examine whether moderate to vigorous physical activity (MVPA) measured using accelerometry is associated with incident falls and whether associations differ according to physical function or history of falls. Design: Prospective study with baseline data collection from 2012 to 2014 and 1 year of follow-up. Setting: Women's Health Initiative participants living in the United States. Participants: Ambulatory women aged 63 to 99 (N = 5,545). Measurements: Minutes of MVPA per day measured using an accelerometer, functional status measured using the Short Physical Performance Battery (SPPB), fall risk factors assessed using a questionnaire, fall injuries assessed in a telephone interview, incident falls ascertained from fall calendars. Results: Incident rate ratios (IRRs) revealed greater fall risk in women in the lowest quartile of MVPA compared to those in the highest (IRR = 1.18, 95% confidence interval = 1.01–1.38), adjusted for age, race and ethnicity, and fall risk factors. Fall rates were not significantly associated with MVPA in women with high SPPB scores (9–12) or one or fewer falls in the previous year, but in women with low SPPB scores (≤ 8) or a history of frequent falls, fall rates were higher in women with lower MVPA levels than in those with higher levels (interaction P <.03 and <.001, respectively). Falls in women with MVPA above the median were less likely to involve injuries requiring medical treatment (9.9%) than falls in women with lower MVPA levels (13.0%) (P <.001). Conclusion: These findings indicate that falls are not more common or injurious in older women who engage in higher levels of MVPA. These findings support encouraging women to engage in the amounts and types of MVPA that they prefer. Older women with low physical function or frequent falls with low levels of MVPA are a high-risk group for whom vigilance about falls prevention is warranted