Hannah Arem

Leisure Time Physical Activity and Mortality: A Detailed Pooled Analysis of the Dose-Response Relationship

IMPORTANCE The 2008 Physical Activity Guidelines for Americans recommended a minimum of 75 vigorous-intensity or 150 moderate-intensity minutes per week (7.5 metabolic-equivalent hours per week) of aerobic activity for substantial health benefit and suggested additional benefits by doing more than double this amount. However, the upper limit of longevity benefit or possible harm with more physical activity is unclear. OBJECTIVE To quantify the dose-response association between leisure time physical activity and mortality and define the upper limit of benefit or harm associated with increased levels of physical activity. DESIGN, SETTING, AND PARTICIPANTS We pooled data from 6 studies in the National Cancer Institute Cohort Consortium (baseline 1992-2003). Population-based prospective cohorts in the United States and Europe with self-reported physical activity were analyzed in 2014. A total of 661,137 men and women (median age, 62 years; range, 21-98 years) and 116,686 deaths were included. We used Cox proportional hazards regression with cohort stratification to generate multivariable-adjusted hazard ratios (HRs) and 95% CIs. Median follow-up time was 14.2 years. EXPOSURES Leisure time moderate- to vigorous-intensity physical activity. MAIN OUTCOMES AND MEASURES The upper limit of mortality benefit from high levels of leisure time physical activity. RESULTS Compared with individuals reporting no leisure time physical activity, we observed a 20% lower mortality risk among those performing less than the recommended minimum of 7.5 metabolic-equivalent hours per week (HR, 0.80 [95% CI, 0.78-0.82]), a 31% lower risk at 1 to 2 times the recommended minimum (HR, 0.69 [95% CI, 0.67-0.70]), and a 37% lower risk at 2 to 3 times the minimum (HR, 0.63 [95% CI, 0.62-0.65]). An upper threshold for mortality benefit occurred at 3 to 5 times the physical activity recommendation (HR, 0.61 [95% CI, 0.59-0.62]); however, compared with the recommended minimum, the additional benefit was modest (31% vs 39%). There was no evidence of harm at 10 or more times the recommended minimum (HR, 0.69 [95% CI, 0.59-0.78]). A similar dose-response relationship was observed for mortality due to cardiovascular disease and to cancer. CONCLUSIONS AND RELEVANCE Meeting the 2008 Physical Activity Guidelines for Americans minimum by either moderate- or vigorous-intensity activities was associated with nearly the maximum longevity benefit. We observed a benefit threshold at approximately 3 to 5 times the recommended leisure time physical activity minimum and no excess risk at 10 or more times the minimum. In regard to mortality, health care professionals should encourage inactive adults to perform leisure time physical activity and do not need to discourage adults who already participate in high-activity levels.

Association of Leisure-Time Physical Activity With Risk of 26 Types of Cancer in 1.44 Million Adults

IMPORTANCE Leisure-time physical activity has been associated with lower risk of heart-disease and all-cause mortality, but its association with risk of cancer is not well understood. OBJECTIVE To determine the association of leisure-time physical activity with incidence of common types of cancer and whether associations vary by body size and/or smoking. DESIGN, SETTING, AND PARTICIPANTS We pooled data from 12 prospective US and European cohorts with self-reported physical activity (baseline, 1987-2004). We used multivariable Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals for associations of leisure-time physical activity with incidence of 26 types of cancer. Leisure-time physical activity levels were modeled as cohort-specific percentiles on a continuous basis and cohort-specific results were synthesized by random-effects meta-analysis. Hazard ratios for high vs low levels of activity are based on a comparison of risk at the 90th vs 10th percentiles of activity. The data analysis was performed from January 1, 2014, to June 1, 2015. EXPOSURES Leisure-time physical activity of a moderate to vigorous intensity. MAIN OUTCOMES AND MEASURES Incident cancer during follow-up. RESULTS A total of 1.44 million participants (median [range] age, 59 [19-98] years; 57% female) and 186 932 cancers were included. High vs low levels of leisure-time physical activity were associated with lower risks of 13 cancers: esophageal adenocarcinoma (HR, 0.58; 95% CI, 0.37-0.89), liver (HR, 0.73; 95% CI, 0.55-0.98), lung (HR, 0.74; 95% CI, 0.71-0.77), kidney (HR, 0.77; 95% CI, 0.70-0.85), gastric cardia (HR, 0.78; 95% CI, 0.64-0.95), endometrial (HR, 0.79; 95% CI, 0.68-0.92), myeloid leukemia (HR, 0.80; 95% CI, 0.70-0.92), myeloma (HR, 0.83; 95% CI, 0.72-0.95), colon (HR, 0.84; 95% CI, 0.77-0.91), head and neck (HR, 0.85; 95% CI, 0.78-0.93), rectal (HR, 0.87; 95% CI, 0.80-0.95), bladder (HR, 0.87; 95% CI, 0.82-0.92), and breast (HR, 0.90; 95% CI, 0.87-0.93). Body mass index adjustment modestly attenuated associations for several cancers, but 10 of 13 inverse associations remained statistically significant after this adjustment. Leisure-time physical activity was associated with higher risks of malignant melanoma (HR, 1.27; 95% CI, 1.16-1.40) and prostate cancer (HR, 1.05; 95% CI, 1.03-1.08). Associations were generally similar between overweight/obese and normal-weight individuals. Smoking status modified the association for lung cancer but not other smoking-related cancers. CONCLUSIONS AND RELEVANCE Leisure-time physical activity was associated with lower risks of many cancer types. Health care professionals counseling inactive adults should emphasize that most of these associations were evident regardless of body size or smoking history, supporting broad generalizability of findings.

A review of web-based weight loss interventions in adults

Unprecedented obesity rates are changing the burden of disease worldwide and obesity‐related health complications are increasing healthcare costs. In response, researchers, clinicians and public health practitioners are seeking new and effective tools such as the Internet to effect weight loss. This review highlights peer‐reviewed literature on randomized controlled trials that examine Internet‐delivered weight loss and maintenance programmes. The scope of this review is broader than previous reviews, including more males and non‐Caucasian participants. The reviewed studies show intervention results ranging from no weight loss to an average loss of 7.6 kg. It is difficult to draw a definitive conclusion on the potential impact of Internet‐based weight loss as study methods are highly variable between papers, low adherence was recorded and not all studies include a control group. As the demand for low‐cost, efficacious interventions that yield statistically significant and/or clinically relevant results grows, more rigorous, population‐specific research is needed to determine if Internet‐delivered interventions may slow or reverse with weight gain and obesity and the associated health consequences.

Pre- and Postdiagnosis Physical Activity, Television Viewing, and Mortality Among Patients With Colorectal Cancer in the National Institutes of Health–AARP Diet and Health Study

PURPOSE Physical inactivity has been associated with higher mortality risk among survivors of colorectal cancer (CRC), but the independent effects of pre- versus postdiagnosis activity are unclear, and the association between watching television (TV) and mortality in survivors of CRC is previously undefined. METHODS We analyzed the associations between prediagnosis (n = 3,797) and postdiagnosis (n = 1,759) leisure time physical activity (LTPA) and TV watching and overall and disease-specific mortality among patients with CRC. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% CIs, adjusting for known mortality risk factors. RESULTS Comparing survivors of CRC reporting more than 7 hours per week (h/wk) of prediagnosis LTPA with those reporting no LTPA, we found a 20% lower risk of all-cause mortality (HR, 0.80; 95% CI, 0.68 to 0.95; P for trend = .021). Postdiagnosis LTPA of ≥ 7 h/wk, compared with none, was associated with a 31% lower all-cause mortality risk (HR, 0.69; 95% CI, 0.49 to 0.98; P for trend = .006), independent of prediagnosis activity. Compared with 0 to 2 TV hours per day (h/d) before diagnosis, those reporting ≥ 5 h/d of TV before diagnosis had a 22% increased all-cause mortality risk (HR, 1.22; 95% CI, 1.06 to 1.41; P trend = .002), and more postdiagnosis TV watching was associated with a nonsignificant 25% increase in all-cause mortality risk (HR, 1.25; 95% CI, 0.93 to 1.67; P for trend = .126). CONCLUSION LTPA was inversely associated with all-cause mortality, whereas more TV watching was associated with increased mortality risk. For both LTPA and TV watching, postdiagnosis measures independently explained the association with mortality. Clinicians should promote both minimizing TV time and increasing physical activity for longevity among survivors of CRC, regardless of previous behaviors.

Prediagnosis Body Mass Index, Physical Activity, and Mortality in Endometrial Cancer Patients

Background Higher body mass index (BMI) and inactivity have been associated with a higher risk of developing endometrial cancer, but the impact on endometrial cancer survival is unclear. Methods Among incident endometrial cancer case subjects in the National Institutes of Health-AARP Diet and Health Study, we examined associations of prediagnosis BMI (n = 1400) and physical activity (n = 875) with overall and disease-specific 5- and 10-year mortality. Using Cox proportional hazards regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for tumor characteristics, treatment, and other risk factors. All statistical tests were two-sided. Results Compared with women with a BMI in the range of 18.5 to less than 25kg/m(2), the hazard ratios for 5-year all-cause mortality were 1.74 (95% CI = 1.13 to 2.66) for BMI in the range of 25 to less than 30kg/m(2), 1.84 (95% CI = 1.17 to 2.88) for BMI in the range of 30 to less than 35kg/m(2), and 2.35 (95% CI = 1.48 to 3.73) for BMI greater than or equal to 35kg/m(2) (P trend < .001). Higher BMI was also statistically significantly associated with poorer endometrial cancer-specific but not cardiovascular disease 5-year mortality. Hazard ratio estimates for 10-year all-cause and endometrial cancer-specific mortality as related to BMI were similar to 5-year hazard ratio estimates, whereas 10-year cardiovascular disease mortality became statistically significant (HR = 4.08; 95% CI = 1.56 to 10.71 comparing extreme BMI groups). More physical activity was related to lower all-cause 5-year mortality (HR = 0.57, 95% CI = 0.33 to 0.98 for >7 hours/week vs never/rarely), but the association was attenuated after adjustment for BMI (HR = 0.64, 95% CI = 0.37 to 1.12). No association was observed between physical activity and disease-specific mortality. Conclusions Our findings suggest that higher prediagnosis BMI increases risk of overall and disease-specific mortality among women diagnosed with endometrial cancer, whereas physical activity lowers risk. Intervention studies of the effect of these modifiable lifestyle factors on mortality are needed.

Obesity and endometrial cancer survival: a systematic review

Although it is known that obesity increases the risk of endometrial cancer and is linked to higher mortality rates in the general population, the association between obesity and mortality among endometrial cancer survivors is unclear. We performed a medline search using exploded Mesh keywords ‘endometrial neoplasms/’ and (‘body mass index/’ or ‘obesity/’) and (‘survival analysis/’ or ‘mortality/’ or (survivor* or survival*).mp.). We also inspected bibliographies of relevant papers to identify related publications. Our search criteria yielded 74 studies, 12 of which met inclusion criteria. Four of the included studies reported a statistically or marginally significant association between obesity and higher all cause mortality among endometrial cancer survivors after multivariate adjustment. The suggestive association between body mass index and higher all cause mortality among women with endometrial cancer was comparable to the magnitude of association reported in prospective studies of healthy women. Of the five studies that examined progression-free survival and the two studies reporting on disease-specific mortality, none reported an association with obesity. Future studies are needed to understand disease-specific mortality, the importance of obesity-onset timing and whether mechanisms of obesity-related mortality in this population of women differ from those of the general population.

A Large Prospective Investigation of Sleep Duration, Weight Change, and Obesity in the NIH-AARP Diet and Health Study Cohort

The relationship between sleep and obesity or weight gain in adults, particularly older populations, remains unclear. In a cohort of 83,377 US men and women aged 51-72 years, we prospectively investigated the association between self-reported sleep duration and weight change over an average of 7.5 years of follow-up (1995-2004). Participants were free of cancer, heart disease, and stroke at baseline and throughout the follow-up. We observed an inverse association between sleep duration per night and weight gain in both men (P for trend = 0.02) and women (P for trend < 0.001). Compared with 7-8 hours of sleep, shorter sleep (<5 hours or 5-6 hours) was associated with more weight gain (in kilograms; men: for <5 hours, β = 0.66, 95% confidence interval (CI): 0.19, 1.13, and for 5-6 hours, β = 0.12, 95% CI: -0.02, 0.26; women: for <5 hours, β = 0.43, 95% CI: 0.00, 0.86, and for 5-6 hours, β = 0.23, 95% CI: 0.08, 0.37). Among men and women who were not obese at baseline, participants who reported less than 5 hours of sleep per night had an approximately 40% higher risk of developing obesity than did those who reported 7-8 hours of sleep (for men, odds ratio = 1.45, 95% CI: 1.06, 1.99; for women, odds ratio = 1.37, 95% CI: 1.04, 1.79). The association between short sleep and excess weight gain was generally consistent across different categories of age, educational level, smoking status, baseline body mass index, and physical activity level.

Prediagnostic lifestyle factors and survival after colon and rectal cancer diagnosis in the National Institutes of Health (NIH)-AARP Diet and Health Study

Few studies have examined the relationship of lifestyle factors with mortality among patients with colorectal cancer.

The Healthy Eating Index 2005 and Risk for Pancreatic Cancer in the NIH–AARP Study

BACKGROUND Dietary pattern analyses characterizing combinations of food intakes offer conceptual and statistical advantages over food- and nutrient-based analyses of disease risk. However, few studies have examined dietary patterns and pancreatic cancer risk and none focused on the 2005 Dietary Guidelines for Americans. We used the Healthy Eating Index 2005 (HEI-2005) to estimate the association between meeting those dietary guidelines and pancreatic cancer risk. METHODS We calculated the HEI-2005 score for 537 218 men and women in the National Institutes of Health-American Association of Retired Persons Diet and Health Study using responses to food frequency questionnaires returned in 1995 and 1996. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of pancreatic cancer according to HEI-2005 quintiles and explored effect modification by known risk factors. P interaction values were calculated using the Wald test. All statistical tests were two-sided. RESULTS We identified 2383 incident, exocrine pancreatic cancer cases (median = 10.5 years follow-up). Comparing participants who met the most dietary guidelines (Q5) with those who met the fewest guidelines (Q1), we observed a reduced risk of pancreatic cancer (HR = 0.85, 95% CI = 0.74 to 0.97). Among men there was an interaction by body mass index (P interaction = .03), with a hazard ratio of 0.72 (95% CI = 0.59 to 0.88) comparing Q5 vs Q1 in overweight/obese men (body mass index ≥ 25 kg/m(2)) but no association among normal weight men. CONCLUSIONS Our findings support the hypothesis that consuming a high-quality diet, as scored by the HEI-2005, may reduce the risk of pancreatic cancer.

Physical activity and cancer-specific mortality in the NIH-AARP Diet and Health Study cohort.

Higher physical activity levels have been associated with a lower risk of developing various cancers and all‐cancer mortality, but the impact of pre‐diagnosis physical activity on cancer‐specific death has not been fully characterized. In the prospective National Institutes of Health‐AARP Diet and Health Study with 293,511 men and women, we studied prediagnosis moderate to vigorous intensity leisure time physical activity (MVPA) in the past 10 years and cancer‐specific mortality. Over a median 12.1 years, we observed 15,001 cancer deaths. Using Cox proportional hazards regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for MVPA with cancer mortality overall and by 20 specific cancer sites, adjusting for relevant risk factors. Compared to participants reporting never/rare MVPA, those reporting >7 hr/week MVPA had a lower risk of total cancer mortality (HR = 0.89, 95% CI 0.84–0.94; p‐trend <0.001). When analyzed by cancer site‐specific deaths, comparing those reporting >7 hr/week of MVPA to those reporting never/rare MVPA, we observed a lower risk of death from colon (HR = 0.70; 95% CI 0.57–0.85; p‐trend <0.001), liver (0.71; 0.52–0.98; p‐trend = 0.012) and lung cancer (0.84; 0.77–0.92; p‐trend <0.001) and a significant p‐trend for non‐Hodgkins lymphoma (0.80; 0.62–1.04; p‐trend = 0.017). An unexpected increased mortality p‐trend with increasing MVPA was observed for death from kidney cancer (1.42; 0.98–2.03; p‐trend = 0.016). Our findings suggest that higher prediagnosis leisure time physical activity is associated with lower risk of overall cancer mortality and mortality from multiple cancer sites. Future studies should confirm observed associations and further explore timing of physical activity and underlying biological mechanisms.