Diaz Keith M, Howard Virginia J, Hutto Brent, Colabianchi Natalie, Vena John E, Safford Monika M, Blair Steven N, Hooker Steven P
From Columbia University Medical Center and Weill Cornell Medical Center, New York, New York; University of Alabama at Birmingham, Birmingham, Alabama; University of South Carolina, Columbia, South Carolina; University of Michigan, Ann Arbor, Michigan; Medical University of South Carolina, Charleston, South Carolina; and Arizona State University, Phoenix, Arizona.
Ann Intern Med. 2017 Oct 3;167(7):465-475. doi: 10.7326/M17-0212. Epub 2017 Sep 12.
Excessive sedentary time is ubiquitous in Western societies. Previous studies have relied on self-reporting to evaluate the total volume of sedentary time as a prognostic risk factor for mortality and have not examined whether the manner in which sedentary time is accrued (in short or long bouts) carries prognostic relevance.
To examine the association between objectively measured sedentary behavior (its total volume and accrual in prolonged, uninterrupted bouts) and all-cause mortality.
Prospective cohort study.
Contiguous United States.
7985 black and white adults aged 45 years or older.
Sedentary time was measured using a hip-mounted accelerometer. Prolonged, uninterrupted sedentariness was expressed as mean sedentary bout length. Hazard ratios (HRs) were calculated comparing quartiles 2 through 4 to quartile 1 for each exposure (quartile cut points: 689.7, 746.5, and 799.4 min/d for total sedentary time; 7.7, 9.6, and 12.4 min/bout for sedentary bout duration) in models that included moderate to vigorous physical activity.
Over a median follow-up of 4.0 years, 340 participants died. In multivariable-adjusted models, greater total sedentary time (HR, 1.22 [95% CI, 0.74 to 2.02]; HR, 1.61 [CI, 0.99 to 2.63]; and HR, 2.63 [CI, 1.60 to 4.30]; P for trend < 0.001) and longer sedentary bout duration (HR, 1.03 [CI, 0.67 to 1.60]; HR, 1.22 [CI, 0.80 to 1.85]; and HR, 1.96 [CI, 1.31 to 2.93]; P for trend < 0.001) were both associated with a higher risk for all-cause mortality. Evaluation of their joint association showed that participants classified as high for both sedentary characteristics (high sedentary time [≥12.5 h/d] and high bout duration [≥10 min/bout]) had the greatest risk for death.
Participants may not be representative of the general U.S. population.
Both the total volume of sedentary time and its accrual in prolonged, uninterrupted bouts are associated with all-cause mortality, suggesting that physical activity guidelines should target reducing and interrupting sedentary time to reduce risk for death.
National Institutes of Health.
久坐时间过长在西方社会普遍存在。以往的研究依靠自我报告来评估久坐时间总量，并将其作为死亡率的一个预后风险因素，且尚未研究久坐时间的累积方式（短时间或长时间累积）是否具有预后相关性。
研究客观测量的久坐行为（包括其总量以及长时间不间断累积情况）与全因死亡率之间的关联。
前瞻性队列研究。
美国本土相邻地区。
7985名年龄在45岁及以上的黑人和白人成年人。
使用佩戴在髋部的加速度计测量久坐时间。长时间不间断久坐以平均久坐时段长度表示。在纳入中度至剧烈身体活动的模型中，计算比较第2至4四分位数与第1四分位数的风险比（HR），以评估每种暴露情况（四分位数切点：总久坐时间为689.7、746.5和799.4分钟/天；久坐时段时长为7.7、9.6和12.4分钟/时段）。
在中位随访4.0年期间，340名参与者死亡。在多变量调整模型中，总久坐时间越长（HR分别为1.22[95%CI，0.74至2.02]；HR为1.61[CI，0.99至2.63]；HR为2.63[CI，1.60至4.30]；趋势P<0.001）以及久坐时段持续时间越长（HR分别为1.03[CI，0.67至1.60]；HR为1.22[CI，0.80至1.85]；HR为1.96[CI，1.31至2.93]；趋势P<0.001）均与全因死亡风险较高相关。对二者联合关联的评估显示，被归类为两种久坐特征均高（久坐时间长[≥12.5小时/天]且久坐时段持续时间长[≥10分钟/时段]）的参与者死亡风险最高。
参与者可能不具有美国普通人群的代表性。
久坐时间总量及其长时间不间断累积均与全因死亡率相关，这表明身体活动指南应旨在减少和中断久坐时间以降低死亡风险。
美国国立卫生研究院。
