Physical Activity Hazard Ratios Research Articles

Associations of postdiagnosis changes in physical activity with all-cause mortality among patients with stage I-IIA colorectal cancer.

87 Background: Several observational studies show an association between physical activity (PA) at diagnosis and reduced risk of mortality among colorectal cancer (CRC) patients, but there has been limited research examining the potential benefit of changes in PA levels after CRC diagnosis. Here we investigate the association between change of PA and all-cause mortality in patients with stage I-IIA CRC receiving resection with curative intent. Methods: Data were used from two large Dutch CRC cohort studies (PLCRC & COLON), which assessed PA at diagnosis (T0), six (T6) and twelve (T12) months after diagnosis, using the SQUASH questionnaire. A total of 2540 stage I-IIA CRC patients with repeated PA measures (i.e. a T0 and at least a T6 or T12 questionnaire) were used for this analysis. Total PA was quantified by calculating Metabolic Equivalent Task (MET) hours per week and categorized as low, moderate, and high PA, based on tertiles of an age- and sex-matched sample of the general population. PA changes were evaluated at T6 and T12 relative to T0. Being active was defined per timepoint as being in the moderate or high total PA group, or adhering to the PA guideline (minimum of 150 minutes per week of moderate-intensity PA). Cox proportional hazards models were used to study the association between PA variables and all-cause mortality, adjusted for age, sex, BMI, and tumor location (colon vs rectum). Results: Median follow-up time was 35 months (interquartile range 19 – 55) during which a total of 133 deaths occurred. Being active at both T0 and T6 compared to being inactive at these timepoints, was associated with a lower rate of all-cause mortality for both PA variables (adjusted hazard ratio (HR) 0.39 [95% confidence interval 0.24-0.63] and 0.41 [0.23-0.72] for total PA and guideline adherence, respectively). Similar results were found when comparing T12 to T0 (being active according to total PA HR 0.20 [0.09-0.42] and guideline adherence HR 0.31 [0.14-0.72]). Changing to either activity or inactivity at T6 or T12 was not significantly associated with all-cause mortality (Table). Conclusions: Maintaining a physically active lifestyle following surgery for stage I to IIA CRC is associated with longer overall survival, reinforcing the recommendations for physical activity. [Table: see text]

Abstract P132: Self-reported Recreational Physical Activity And Incident Venous Thromboembolism Risk In The Women’s Health Initiative

Introduction: The association between physical activity (PA) and incident venous thromboembolism (VTE) is inconsistent and incompletely characterized. Hypothesis: Higher amounts of self-reported total PA will be associated with a lower risk of incident VTE. Methods: Eligible women were Women’s Health Initiative (WHI) Hormone Therapy (HT) trial and Observational Study (OS) participants without prior VTE, able to walk at least one block, with baseline PA data (n=110,631). At multiple timepoints, women reported their current usual frequency and duration of walking and low, moderate, and strenuous intensity recreational PA, which were used to estimate energy expended. VTE, including deep vein thrombosis and pulmonary embolism, were validated in the WHI-HT and self-reported in the WHI-OS. Multivariable-adjusted (Table) Cox Proportional Hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of time-varying total PA and incident VTE risk, with women censored at death, loss to follow-up, and three years after their final PA measure. Results: At baseline, women were 64 years of age on average. Over an average of 9.9 years of follow-up, 1,403 women experienced incident VTE. In primary confounder-adjusted models, compared with women who reported no PA, higher tertiles of total PA were associated with a lower risk of incident VTE (high vs. no PA HR=0.60; 95% CI: 0.51, 0.71; p-trend<0.001) (Table). Further adjustment for potential mediators on the causal pathway (physical function, self-reported health, body mass index [BMI], cardiovascular-related factors) attenuated but did not eliminate this association (high vs. no PA HR=0.81; 95% CI: 0.68, 0.97; p-trend=0.017). Conclusions: Compared to no PA, higher tertiles of total PA were associated with a lower risk of incident VTE, even after adjusting for potential mediators reflecting physical function, health, BMI, and cardiovascular risk. Our results add to the apparent health benefits of even moderate amounts of recreational PA.

Accelerometer-measured physical activity and sedentary time in a cohort of US adults followed for up to 13 years: the influence of removing early follow-up on associations with mortality

BackgroundObservational studies linking physical activity with mortality are susceptible to reverse causation bias from undiagnosed and prevalent diseases. Researchers often attempt to deal with reverse causation bias by excluding deaths occurring within the first 1 or 2 years from the analysis, but it is unclear if excluding deaths within this time-frame is sufficient to remove bias.MethodsWe examined associations between total and intensity-specific physical activity and sedentary time with all-cause mortality in a prospective cohort of 3542 individuals from the 2003–2006 NHANES cycles. In order to yield measures of association hypothesized as minimally influenced by reverse causation bias the primary analysis excluded individuals with < 5 years of follow-up. Accelerometer-measured physical activity was linked with recently updated vital status from the National Death Index with a median follow-up of 10.8 years.ResultsHazard ratios (95% confidence intervals) were 0.74 (0.53, 1.04), 0.52 (0.37, 0.73), and 0.61 (0.38, 1.01) for ascending quartiles of total physical activity against the least active reference. Hazard ratios for ascending moderate-to-vigorous physical activity quartiles against the reference were 0.67 (0.47, 1.96), 0.67 (0.47, 0.95), and 0.68 (0.39, 1.18). Associations for light intensity physical activity and sedentary time were smaller in magnitude and all confidence intervals included unity. Total activity and moderate-to-vigorous physical activity hazard ratios from analyses only excluding deaths within the first 2 years were inflated by 13 and 26% relative to analysis restricted to ≥5 years of follow-up.ConclusionsThe pattern of associations suggested total physical activity and moderate-to-vigorous physical activity were associated with lower mortality after more than 10 years of follow-up and excluding the first 5 years of observation time to minimize the impact of reverse causation bias. Excluding deaths within the first 2 years appeared insufficient to minimize the impact of reserve causation bias.

Accelerometer-measured Physical Activity and Breast Cancer Incidence in the WHI OPACH Study

Abstract To examine the associations between accelerometer-measured physical activity (PA) and breast cancer incidence among a cohort of postmenopausal women. Methods: This longitudinal study included 6,382 women (mean age 79 ± 6 years; 49.4% non-Hispanic white, 33.7% non-Hispanic Black, 16.9% Hispanic) without a history of breast cancer who participated in the Women's Health Initiative (WHI) Objective Physical Activity and Cardiovascular Health (OPACH) Study. During 2012–2013, participants wore an ActiGraph GT3X+ accelerometer at the hip for up to 7 days. Accelerometer intensity counts were specially calibrated to PA in older women. The resulting data were used to compute minutes per day spent in total PA, light intensity PA (e.g., usual walking), and moderate-to-vigorous PA (MVPA; e.g., brisk walking). Physician-adjudicated first diagnosis of in situ (n = 18) or invasive (n = 103) breast cancer was ascertained over a median follow-up of 5.6 years. We used multivariable Cox regression to estimate covariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for tertiles and one-standard deviation (SD) unit increments of PA exposures in association with breast cancer incidence. We examined effect measure modification by age, race/ethnicity, body mass index (BMI), and smoking history. Results: The highest (vs. lowest) tertile of total PA was associated with a breast cancer incidence HR of 0.67 (95% CI = 0.43–1.05) and this association was more pronounced for MVPA (HR = 0.61, 95% CI = 0.38–1.00) than for light PA (HR = 0.81, 95% CI = 0.53–1.26). In BMI-stratified analyses, HRs for total (PInteraction = 0.04) and light PA (PInteraction = 0.01), but not MVPA (PInteraction = 0.79), were stronger among women with BMI ≥ 30 kg/m2 (n cancer events = 48; total PA HRper one-SD = 0.69, 95% CI = 0.50–0.96; light PA HR = 0.69, 95% CI = 0.50–0.95) than among women with BMI &amp;lt; 30 kg/m2 (n cancer events = 73; total PA HRper one-SD = 1.07, 95% CI = 0.84–1.38; light PA HR = 1.13, 95% CI = 0.89–1.44). Age, race/ethnicity, and cigarette smoking history did not strongly modify these associations (PInteraction's ≥ 0.16). Conclusions: Engaging in high levels of PA may play a beneficial role in the prevention of breast cancer in older women, and in particular among postmenopausal women with BMI ≥ 30 kg/m2.

Multinational Population-Based Health Surveys Linked to Outcome Data: An Untapped Resource

ABSTRACTObjectivesIncreasingly, national health surveys are being linked to vital statistics and health care information, providing a new and unique source of individual population health data. Given that nationally-representative health surveys are performed in over a hundred countries, these linkages create comprehensive data sets that are potentially larger than most existing cohort studies. To date, this resource has not been utilized.&#x0D; ApproachThe purpose, study base, content and methods of the Canadian Community Health Survey (CCHS) cycles 2.1 (2003-04) and 3.1 (2005-06) and the United States 2000 and 2005 National Health Interview Survey (NHIS) were examined for comparability and consistency. Smoking, alcohol, physical activity and diet questions were identified, question construct and response categorization were compared, and variable constructions possible for both national health surveys were created. All respondents 20+ years of age were identified and stratified by country and sex. Cox proportional hazard models were used to estimate 5-year hazards of mortality associated with the common smoking, alcohol, physical activity and diet variables.&#x0D; ResultsThe CCHS and NHIS are highly consistent and comparable. Health behaviour questions are similar and permit the creation of smoking, alcohol, physical activity and diet variables that are comparable across surveys. A total of 284 475 survey respondents from Canada and the United States (CCHS, N= 226 731; NHIS, N= 57 744) were included. The largest mortality hazards were associated with female heavy smokers in both Canada (HR: 2.91; 95% CI: 2.52, 3.37) and the United States (Female HR: 2.96; 95% CI: 2.59, 3.38), compared to non-smokers. Moderate variation in the age adjusted all-cause mortality hazard ratios was observed; both smoking and physical activity hazard ratios were consistently higher in the United States than in Canada.&#x0D; ConclusionThis study provides initial support for the methodological feasibility of pooling linked population health surveys however, challenges introduced by dissimilarities will require the use of innovative methodologies, and discussions regarding how to manage jurisdictional data restrictions and privacy issues are needed. Pooled population health data has the potential to improve national and international health surveillance and public health.