Background Sedentary time is an independent risk factor for obesity.
Objective This study is designed to understand the status quo of screen-based sedentary time of elderly residents in China, analyze its relationship with obesity, so as to provide a scientific basis for making obesity intervention strategies for elderly residents.
Methods The data were derived from the China Nutritional Transition Cohort Study 2015, where elderly residents aged 60 years and above in 15 provinces (including municipalities and autonomous regions) (hereinafter referred to as 15 provinces) in China were selected as study subjects and were asked to complete a questionnaire on average weekly sedentary time (screenbased and non-screen-based) and physical activity in the past year, as well as anthropometric measurements such as height, weight, and waist circumference. Variance analysis was used to compare average screen-based sedentary time between different gender, age, residence, and physical activity level groups. Chi-square test was used to analyze the distribution differences in gender, age, residence, and physical activity level among subjects with different screen-based sedentary time. Multiple linear regression was used to analyze the relationship of screen-based sedentary time with waist circumference and body mass index (BMI). Multivariate logistic regression was used to analyze the risk of central obesity and obesity (BMI≥28kg/m2) at different screen-based sedentary time levels.
Results The average screen-based sedentary time of 5 047 elderly residents aged 60 years and above in 15 provinces of China in 2015 was (19.7±17.3) h/week, among which the average TV time was (18.7±16.4) h/week and the average computer time was (1.0±5.3) h/week; the average non-screen-based sedentary time was (1.2±5.3) h/week. The average screen-based sedentary time was higher in males (20.8±18.0) h/week than in females (18.7±16.5) h/week (P < 0.001), decreasing with older age (Ptrend=0.022), and higher in urban areas (21.4±17.8) h/week than in rural areas (18.4±16.8) h/week (P < 0.001). The proportions of low, middle, and high levels of screen-based sedentary time was 40.4%, 41.6%, and 18.0%, respectively. The proportion of high level of screen-based sedentary time was higher in males (20.6%) than in females (15.6%) (P < 0.001), decreasing with older age (Ptrend < 0.001), and higher in urban areas (22.4%) than in rural areas (14.7%) (P < 0.001), decreasing with higher physical activity level (Ptrend < 0.001). The waist circumference and central obesity rate of elderly female residents were positively correlated with screen-based sedentary time levels: compared with the low screen-based sedentary time level, the waist circumference of those with middle and high screen-based sedentary time levels increased by 1.316 cm (P=0.019) and 1.708cm (P=0.026) respectively, and the OR(95%CI) of central obesity was 1.209 (1.009-1.449) and 1.316 (1.024-1.691), respectively.
Conclusion The average screen-based sedentary time and the proportion of high-level screen-based sedentary time of elderly residents in 15 provinces of China are correlated with gender, residence, and age. In addition, the proportion of high-level screen-based sedentary time is also correlated with physical activity level. Higher levels of screen-based sedentary time in elderly female residents are positively correlated with increased waist circumference and the risk of central obesity.
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