Aviroop Biswas

Sedentary Time and Its Association With Risk for Disease Incidence, Mortality, and Hospitalization in Adults: A Systematic Review and Meta-analysis

Adults are advised to accumulate at least 150 minutes of weekly physical activity in bouts of 10 minutes or more (1). The intensity of such habitual physical activity has been found to be a key characteristic of primary and secondary health prevention, with an established preventive role in cardiovascular disease, type 2 diabetes, obesity, and some cancer types (2, 3). Despite the health-enhancing benefits of physical activity, this alone may not be enough to reduce the risk for disease and illness. Population-based studies have found that more than one half of an average persons waking day involves sedentary activities ubiquitously associated with prolonged sitting, such as watching television and using the computer (4). This lifestyle trend is particularly worrisome because studies suggest that long periods of sitting have deleterious health effects independent of adults meeting physical activity guidelines (57). Moreover, physical activity and sedentary behaviors may be mutually exclusive. For example, some persons who achieve their recommended physical activity targets may be highly sedentary throughout the remainder of their waking hours, whereas others who may not regularly participate in physical activity may be nonsedentary because of their leisure activities, workplace environments, or both (8). Although studies and subgroups of systematic reviews have explored the independent association between sedentary behaviors and outcomes after adjustment for physical activity, the magnitude and consistency of such associations and the manner by which they change according to the level of participation in physical activity remain unclear (911). The objective of this meta-analysis was to quantitatively evaluate the association between sedentary time and health outcomes independent of physical activity participation among adult populations. We hypothesized that sedentary time would be independently associated with both cardiovascular and noncardiovascular outcomes after adjusting for participation in physical activity but that the relative hazards associated with sedentary times would be attenuated in those who participate in higher levels of physical activity compared with lower levels (10). Methods Data Sources and Searches The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in the conduct and reporting of this meta-analysis (9). Published studies on the association between sedentary behavior and various health outcomes were identified and cross-checked by 2 reviewers through a systematic search of the MEDLINE, PubMed, EMBASE, CINAHL, Cochrane Library, Web of Knowledge, and Google Scholar databases. The health outcomes included all-cause mortality, cardiovascular disease incidence (including diabetes), cardiovascular disease mortality, cancer incidence, cancer mortality, and all-cause hospitalizations. Searches were restricted to English-language primary research articles through August 2014 with no publication date limitations (Supplement). The following keywords were applied to the search: (exercise OR physical activity OR habitual physical activity) AND (sedentar* OR inactivity OR television OR sitting) AND (survival OR morbidity OR mortality OR disease OR hospital* OR utilization). References from relevant publications and review articles were hand-searched to supplement the electronic searches. A broad and comprehensive search strategy was chosen to encompass the range of outcomes associated with sedentary behavior among different populations or settings and variations in the operational definition of leisure-time sedentary behavior. Supplement. Search Strategy Supplement. Original Version (PDF) Study Selection The inclusion criteria were primary research studies that assessed sedentary behavior in adult participants as a distinct predictor variable, independent of physical activity and correlated to at least 1 health outcome. We broadly defined sedentary behavior as a distinct class of waking behaviors characterized by little physical movement and low-energy expenditure (1.5 metabolic equivalents), including sitting, television watching, and reclined posture (11). We allowed for studies that assessed the effects of varying intensities of physical activity, provided that they also correlated a measure of sedentary behavior with an outcome. We excluded studies that assessed nonadult populations (such as children and youth), those that did not adjust for physical activity in their statistical regression models or only assessed sedentary behavior as a reference category to the effects of physical activity, and those that measured sedentary behavior as the lowest category of daily or weekly physical activity. Data Extraction and Quality Assessment Data were extracted from all articles that met selection criteria and deemed appropriate for detailed review by 3 authors. If several articles of the same study were found, then data were extracted from the most recently published article. Details of individual studies were collected and characterized on the basis of authors or year of publication; study design; sample size or characteristics (age and sex); data collection methods; study outcomes; study limitations; and hazard ratios (HRs), odds ratios, or relative risk ratios (and their associated 95% CIs or SEs). We restricted studies reporting health outcomes to those with direct associations with death, disease incidence (that is, risk for disease in a given period), and health service use (that is, change in health service use) outcomes. This led to the exclusion of studies reporting indirect surrogate outcomes with inconsistent clinical end points and cutoffs (such as insulin sensitivity, quality of life, activities of daily living, metabolic biomarkers, the metabolic syndrome, and weight gain). Our studys primary exposure was overall sedentary or sitting time (hours per week or hours per day). Studies reporting information on total screen time (television or computer screen use), television viewing time, and metabolic equivalents (hours per week) were also abstracted when information on the primary exposure was unavailable. We assessed articles for quality on the basis of methods used by Proper and colleagues (12). Their quality assessment tool had been previously validated (face and content) and evaluated to limit the risk of bias from study participation, study attrition, measurement of prognostic factors, measurement of and controlling for confounding variables, measurement of outcomes, and analysis approaches (13, 14). Each study was evaluated according to a standardized set of predefined criteria consisting of 15 items (Table 1) (15). The use of the original quality assessment tool was expanded to permit and score nonprospective studies. The items of the tool assessed study quality within the domains of study population, study attrition, data collection, and data analysis. Each quality criterion was rated as positive, negative, or unknown. As with other meta-analyses, we required positive quality criteria of 8 items or more to be included in our study (12, 16). Two reviewers independently scored each article for quality. Any scoring inconsistencies were discussed with an additional reviewer. Scores from each reviewer were averaged to attain a final quality score assessment and verified by a single reviewer. When such data were available, we also considered whether the effects of prolonged bouts of sedentary time were modified by the highest or lowest reported participation in physical activity (herein termed as joint effects). Table 1. Criteria List for the Assessment of the Quality of Prospective and Nonprospective Studies* Data Synthesis and Analysis All meta-analyses were done using Comprehensive Meta-analysis, version 2 (Biostat), and the metafor package of R (R Foundation for Statistical Computing) (17, 18). Odds ratios, relative risk ratios, and HRs with associated 95% CIs were collected from studies for each outcome, if available. We considered relative risk ratios to be equal to HRs, and when only odds ratios were provided, they were approximated to relative risk ratios in which we used the assumption of rare events according to methods described and demonstrated elsewhere (19, 20). When studies presented several statistical risk-adjustment models, we only considered relative risk ratios associated with the statistical models that contained the fewest number of additional covariates beyond physical activity to enhance comparability across studies. Adjustment for physical activity (rather than moderate to vigorous physical activity) allowed for a broader range of studies, some of which may not have specified the intensity of physical activity in regression models. KnappHartung small sample estimation was used to pool the analysis of the overall effect size for each outcome. Studies that separately presented results for men and women were combined using a fixed-effects model. We received a 79% response rate from authors we had contacted to provide additional statistical information for our meta-analysis (11 out of 14). Potential modifying effects of physical activity on sedentary time were examined by comparing the statistical effect sizes of any studies that reported the longest period of sedentary time with the highest and lowest duration and intensity of physical activity. Statistical heterogeneity was assessed using the Cochran Q statistic and the I 2 statistic of the proportion of total variation because of heterogeneity (21). When we saw substantial heterogeneity, we considered a KnappHartung modified random-effects model (22). For the summary estimate, a P value less than 0.05 was considered statistically significant. The potential for small study effects, such as publication bias, was explored graphically using funnel plots through the Egger test of asymmetry and quantitatively by the Egger linear regression method (23). We also did a sensitivit

Safety Aspects of Implantable Cardioverter Defibrillators in PatientsParticipating in Exercise Therapy: A Systematic Review and Meta-Analysis

Background: The safety of exercise therapy (ET) in patients with an implantable cardioverter defibrillator (ICD) remains unclear. We sought to explore the current state of evidence and conduct a systematic review on the safety of ICDs during ET. Methods: A systematic review was performed using CINAHL, Cochrane Library, EMBASE, Google Scholar, MEDLINE, PubMed (excluding Medline records), and Web of Science databases searched through April 2015. Studies that quantitively assessed adverse events during ET and after ET in ICD patients compared to one of two control groups (non-ICD ET or non-ET ICD patients) were included. The primary outcome was adverse events during ET. Secondary outcomes were events during ET and follow-up. Results: Meta-analyses were performed on ten eligible studies. During ET, ICD patients experienced an increased risk of adverse events [relative risk (RR)=2.63, 95% confidence interval (CI) (1.71-4.05), P=0.01] compared to non-ICD controls. There was no significant increase risk of adverse events compared to non-ET ICD controls [RR=0.99, 95% CI (0.11-8.95), P=0.99]. ET-ICD patients had fewer adverse events during follow-up compared to non-ET ICD populations [RR=0.90, 95% CI (0.82- 0.99), P=0.02]. A sensitivity analysis including only randomized trials showed similar findings showed no difference in the primary outcome. Conclusions: Our analysis showed increased adverse event during exercise in ICD patients as compared with non-ICD patients. Comparative adverse event rates between exercising and sedentary ICD patients were similar during ET and lower after ET, suggesting that exercise can be safe and potentially protective among ICD patients. More rigorous data from larger randomized trials is needed to further quantify the incremental risk of exercise in high-risk ICD populations.

Patient and practitioner perspectives on reducing sedentary behavior at an exercise-based cardiac rehabilitation program

Abstract Purpose: To understand the awareness of sedentary behavior, as well as the perceived facilitators and barriers to reducing sedentary behaviors from the perspectives of patients undertaking an exercise-based cardiac rehabilitation program, and from staff involved in supporting patient self-management. Materials and methods: A qualitative study was conducted at a large cardiac rehabilitation program in a metropolitan city in Canada. Guided by an ecological framework, semi-structured interviews were conducted individually with 15 patients, and in two focus groups with six staff. Transcribed interviews were analyzed by thematic analysis. Results: Patients placed little importance on reducing sedentary behavior as they were unconvinced of the health benefits, did not perceive themselves to be sedentary, or associated such behaviors with enjoyment and relaxation. While staff were aware of the risks, they saw them as less critical than other health behaviors. Intrapersonal factors (physical and psychosocial health) and environment factors (the information environment, socio-cultural factors) within leisure time, the home, and work, influenced sedentary behavior. Conclusions: While these findings require further testing, future interventions may be effective if aimed at increasing awareness of the health benefits of reducing sedentary behavior, utilizing existing behavior change strategies, and using a participatory approach to tailor strategies to patients. Implications for rehabilitation Cardiac rehabilitation programs effectively use exercise promotion to improve the health of people with established cardiovascular disease. As sedentary lifestyles become more prevalent, recommendations to reduce the health risks of prolonged sedentary behavior that are specific to the characteristics and prognostic profiles of cardiac rehabilitation patients are needed. Cardiac rehabilitation programs must consider extending existing behavior change strategies utilized for exercise promotion towards addressing sedentary behaviors in order to be effective at reducing the sedentary time of patients. A participatory approach involving both patients and health professionals can support patients in reducing their sedentary behavior by providing a supportive environment for behavior change, increasing awareness and understanding of risks, discussing the feasibility of potential strategies, and setting achievable and actionable goals.

The energy expenditure benefits of reallocating sedentary time with physical activity: a systematic review and meta-analysis

Background We compared direct and daily cumulative energy expenditure (EE) differences associated with reallocating sedentary time to physical activity in adults for meaningful EE changes. Methods Peer-reviewed studies in PubMed, Medline, EMBASE, CINAHL, PsycINFO, Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews were searched from inception to March 2017. Randomized and non-randomized interventions with sedentary time and EE outcomes in adults were included. Study quality was assessed by the National Heart Lung and Blood Institute tool, and summarized using random-effects meta-analysis and meta-regression. Results In total, 26 studies were reviewed, and 24 studies examined by meta-analysis. Reallocating 6-9 h of sedentary time to light-intensity physical activity (LIPA) (standardized mean difference [SMD], 2.501 [CI: 1.204-5.363]) had lower cumulative EE than 6-9 h of combined LIPA and moderate-vigorous intensity physical activity (LIPA and moderate-vigorous physical activity [MVPA]) (SMD, 5.218 [CI: 3.822-6.613]). Reallocating 1 h of MVPA resulted in greater cumulative EE than 3-5 h of LIPA and MVPA, but <6-9 h of LIPA and MVPA. Conclusions Comparable EE can be achieved by different strategies, and promoting MVPA might be effective for those individuals where a combination of MVPA and LIPA is challenging.

Examining the efficacy of a novel integrative exercise-based intervention in reducing the sedentary time of a clinical population

Prolonged sedentary time is increasingly abundant in modern societies and independently associated with cardiovascular and non-cardiovascular mortality [1,2]. Intervention strategies targeted at sedentary time have typically been designed to reallocate an individual’s sedentary time to physical activity [3]. While evidence has established the efficacy of exercise-based interventions for increasing moderate-vigorous physical activity (MVPA), it is unclear whether these interventions have spillover effects on the daily sedentary time of individuals.

Naturally occurring workplace facilities to increase the leisure time physical activity of workers: A propensity-score weighted population study

The benefit of providing access to physical activity facilities at or near work to support the leisure time physical activity (LTPA) of workers is uncertain. We examined the association between access to physical activity facilities at or near work and the LTPA of workers after adjusting for a range of individual and occupational characteristics. Data was obtained from 60,650 respondents to the 2007–2008 Canadian Community Health Survey. Participants were employed adults ≥18 years of age who had no long-term health condition which reduced their participation in physical activity. Latent class analysis determined naturally occurring combinations of physical activity facilities at or near work. Each combination was balanced by 19 individual and occupational covariate characteristics using inverse probability of treatment weights derived from propensity scores. The association between combinations of physical activity facilities at or near work on LTPA level was estimated by multinomial logistic regression. Five different combinations of physical activity facilities were available to respondents at or near work. Data were analyzed in 2017. All possible physical facilities increased the likelihood for LTPA (OR, 2.08, 95% CI, 1.03–4.20) and other combinations were also positively associated. Respondents with no physical activity facilities were characterized as having a low education, low income, high physically demanding work, poor health and mental health, non-white racial background, and being an immigrant. Access to supportive workplace environments can help workers be physically active. Future research should assess a range of personal, social and environmental factors that may be driving this relationship.

Access to Showers and Change Rooms at Work Associated With Active Commuting Among Older Workers: Findings From a National Population Survey:

Access to workplace showers and change rooms (WS/CR) has been found to be associated with active commuting (AC). Yet it is unclear whether this extends to older workers. We examined the association between WS/CR and AC (walking, cycling) comparing older and younger workers. Data came from 53,294 respondents to the 2007-2008 Canadian Community Health Survey. Associations between WS/CR and walking and cycling were analyzed for main effects and by age and sex using logistic regression. Compared with younger ages, workers 50 to 75 years old were more likely to cycle to work if WS/CR were available (odds ratio [OR] = 1.71, 95% confidence interval [CI] = [1.13, 2.58]), though the overall and sex-related associations between WS/CR and AC were nonsignificant. WS/CR may be a promising strategy to promote AC particularly among older workers. With large numbers of middle- and older-aged adults working longer, the implications of AC for sustaining good health may be considerable.

Is promoting six hours of standing an appropriate public health message

We read with great interest the recent article by Saeidifard and colleagues. The authors should be congratulated on systematically reviewing the available research evidence on the extra energy expenditures associated with standing compared to sitting, and providing a consolidated estimate of 0.15 kcal/min (or 9 kcal per hour) difference in energy expenditure for these two activities. From this estimate they suggest that substituting 6 hours of sitting per day with standing would result in an additional 54 kcal in daily energy expenditure (approximately equivalent to the energy intake from eating one slice of bread), and conclude that standing can be a possible solution to long-term weight gain, or even a solution for weight loss. While we see the merit in replacing sitting with other activites that have higher energy expenditures, we have concerns regarding the practical and public health implications of the conclusion to stand for 6 hours. While standing can be a simple substitute for sitting, promoting 6 hours or more of standing per day is unlikely to be a practical solution for sedentary lifestyle-related weight gain and may pose important health hazards, including those related to cardiovascular disease. First, we question whether many adults can easily achieve an additional 6 hours of standing by choice over the course of a typical 16 hour waking day and wonder how this standing might be accumulated. For example, standing accumulated through a pattern of switching between sitting and standing throughout the day will require individuals regularly to overcome the unconscious decisions (e.g. automatic processes, implicit attitudes, habit) that lead to sitting. While the authors suggest that interventions promoting moderate to vigorous-intensity physical activity are faced with several barriers that limit their effectiveness, we are unsure whether promoting standing for a length of time approximately six to nine times longer than currently recommended for moderate to vigorous-intensity physical activity represents an attractive substitute for most of the population. Also, there are potentially harmful consequences of spending long periods of time standing. While the authors suggest no studies assess the potential effects of prolonged motionless standing, this is not true. Although limited in number, there are studies demonstrating increases in musculoskeletal and cardiovascular risks from prolonged standing. The link between prolonged standing and increased cardiovascular risk is thought to be generated through the pooling of blood in the lower limbs, increased venous pressure and reduced plasma volume. We note that these studies are set in work environments, as these environments are likely to be the only environment where people will stand for prolonged periods of time and this is often because it is an (unnecessary) job requirement. Taken together, we feel that regular physical activity provides a more efficient strategy for preventing weight gain and promoting health than promoting excessive periods of time standing. Meeting and exceeding recommendations of 150 minutes of moderate to vigorousintensity physical activity a week can potentially reduce or even eliminate the mortality risks of prolonged sitting. 10 Physical activity also confers important health benefits including cardiopulmonary fitness, which is one of the most important modifiable prognostic determinants of health and is unlikely to be accrued through simply standing. Nevertheless, increasing physical activity levels is itself a challenge and the global prevalence of populations reaching recommended levels remains suboptimal. Therefore, while it remains clear that reducing sitting time should be encouraged, the question about what to replace sitting with and for how long is more complex. To move forward we need studies that better elucidate how to create environments that help people to sit less, and enable these changes to be maintainable for the