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Obesity: Behavioral Interventions that Aim to Reduce Recreational Sedentary Screen Time Among Children

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What the CPSTF Found

About The Systematic Review

The CPSTF finding is based on evidence from a Community Guide systematic review completed in 2008 (7 studies with 9 study arms, search period 1966–July 2007) combined with an updated search for evidence in 2013 (42 studies with 53 study arms, search period April 2007–June 2013).

The systematic review was conducted on behalf of the CPSTF by a team of specialists in systematic review methods, and in research, practice, and policy related to obesity prevention and control.

This finding updates and replaces the 2008 CPSTF findings on Behavioral Interventions to Reduce Screen Time pdf icon [PDF - 202 kB] and Mass Media Interventions to Reduce Screen Time pdf icon [PDF - 179 kB] and replaces the 2000 review on Behavioral and Social Approaches to Increase Physical Activity: Classroom-Based Health Education to Reduce TV Viewing and Video Game Playing pdf icon [PDF - 234 kB].

Context

Childhood obesity has been positively associated with time spent watching TV (Marshall, et al. 2004, Tremblay, et al. 2011). In the United States, children ages 8–18 years report an average of 7 hours of screen time per day, of which 4.5 hours are spent watching TV content such as TV programs, DVDs, or movies, viewed on a TV, computer, cell phone, or other device (Rideout, et al. 2010). Children ages 5 years and younger spend an average of 2 hours per day with screen media (i.e., TV, DVDs, videos, video/computer games), of which approximately 1.5 hours are spent watching TV or videos (Rideout 2011).

Summary of Results

Detailed results from the systematic review are available in the CPSTF Finding and Rationale Statement pdf icon [PDF - 687 kB].

The systematic review included 49 studies with 62 study arms.

  • Screen Time Outcomes
    • The amount of time spent on any screen decreased by a median of 26.4 minutes/day (34 study arms)
      • Screen-time-only interventions: median decrease of 82.2 minutes/day (11 study arms)
      • Screen-time-plus interventions: median decrease of 21.6 minutes/day (23 study arms)
  • Physical Activity Outcomes
    • Accelerometer counts measured physical activity through a small monitor worn with a belt clip.
      • Screen-time-only interventions: no study arms
      • Screen-time-plus interventions
        • Screen time contingent on physical activity: median increase of 130.0 counts per day (3 study arms)
        • Screen time not contingent on physical activity: median increase of 66.0 counts per day (4 study arms)
        • Screen time not contingent on physical activity: median increase of 3.6 counts per minute (3 study arms)
      • Small, positive effects were reported for other physical activity outcomes (e.g., pedometer steps of physical activity, score on a fitness test, and duration of physical activity).
    • Dietary Outcomes
      • Total energy intake (kcal/day)
        • Screen-time-only interventions: decrease of 75 calories/day (1 study arm)
        • Screen-time-plus interventions: decrease of 117.9 calories /day (5 study arms)
      • Small, positive effects were reported for other dietary outcomes (e.g., eating meals or snacking with the TV on, daily snack intake, sugar-sweetened beverage intake, and fruit and vegetable intake).
    • Weight-Related Outcomes
      • Body mass index (BMI): median decrease of 0.09 kg/m2 (15 study arms)
      • BMI Z-score: median decrease of 0.13 (14 study arms)
        • BMI Z-score is a standard deviation score that indicates how a child’s BMI compares to the average for their age group and sex.
    • Obesity Prevalence
      • Proportion of participants who are obese: median decrease of 2.3 percentage points (14 study arms)

Summary of Economic Evidence

Detailed results from the systematic review are available in the CPSTF Finding and Rationale Statement pdf icon [PDF - 687 kB].

The economic review included three models from two studies that were based on randomized controlled trials included in the effectiveness review. A general conclusion about cost-effectiveness could not be determined because results from this small body of evidence were mixed. Monetary values are reported in 2013 U.S. dollars.

Intervention cost:

Intervention cost included the cost of measuring and tracking devices, staff time in counseling and education sessions, training, educational materials, and supplies.

  • The cost per person per year was $43 for a screen-time-plus intervention and $248 for a screen-time-only intervention.
  • The higher cost for the screen-time-only intervention was partially explained by the inclusion of an electronic monitoring device, a greater number of sessions, and labor costs associated with tracking and monitoring outcomes.

Healthcare Cost and QALY:

Healthcare costs are avoided and quality-adjusted life years (QALYs) are saved when the intervention reduces illness and death associated with overweight-related diseases and conditions.

  • The models used in both the screen-time-plus and screen-time-only studies drew from longitudinal data of U.S national surveys to estimate that each prevented case of overweight in adulthood would avert about $4000 in healthcare costs and increase QALYs saved by 0.71.

Cost-effectiveness:

Cost-effectiveness is measured as net cost (intervention cost minus healthcare cost avoided) per QALY saved. An intervention is considered cost-effective when cost-effectiveness is less than or equal to a conservative threshold of $50,000 per QALY saved.

  • Both studies evaluated the models based on a sensitivity analysis of key determinant variables of cost-effectiveness: size of intervention group; intervention effectiveness; transition of weight status to adulthood; intervention cost per person; and 50% relapse to overweight.
  • Both studies modeled the screen-time-plus intervention, finding it to be cost-effective.
    • Cost per QALY saved ranged from $7,500 to $22,900 depending on assumptions made.
  • One study modeled the screen-time-only intervention and found the intervention was not cost-effective.
    • Cost per QALY saved ranged from $26,000 to $115,000 depending on assumptions made.

Applicability

Based on results for interventions in different settings and populations, findings should be applicable to the following:

  • The United States or other high- or medium-income countries
  • Children ages 13 years and younger
  • Males and females
  • Different racial and ethnic populations
  • All socioeconomic levels
  • Normal weight, overweight, and obese populations
  • Urban and suburban settings

Evidence Gaps

Additional research and evaluation are needed to answer the following questions and fill existing gaps in the evidence base. (What are evidence gaps?)

  • Which combinations of intervention components are most effective? Which components are critical to success?
  • Are interventions effective with teens older than 13 years of age and with adults?
  • Are interventions effective in rural settings?
  • What are other benefits and implications of reduced screen time? For example, does a reduction in screen time mean other sedentary behaviors will be substituted (e.g., reading for leisure, listening to music, time spent on homework)? And, do reductions in screen time lead to other health benefits, such as improved sleep quality?

Study Characteristics

  • Studies included randomized controlled trials (RCT) or group RCTs (37 studies), single group before-after studies (5 studies), before-after with a comparison group (4 studies), and a non-randomized trial (1 study).
  • Studies were conducted in the United States (30 studies), Australia (6 studies), the United Kingdom (4 studies), Canada (2 studies), France (1 study), the Netherlands (1 study), New Zealand (1 study), Sweden (1 study), and Switzerland (1 study).
  • Studies mostly targeted children ages 13 years and younger (46 studies). No studies targeted adolescents ages 14-18 years.
  • Nine studies were conducted among populations with lower economic status. Of these, three studies targeted low-income African-American children, two studies targeted Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) participants, one study targeted Head Start program participants, and three studies targeted disadvantaged children.
  • Six studies targeted overweight or obese populations.
  • Family-based social support was the most common intervention component.
  • Evaluated programs were most commonly implemented in schools (20 studies), and of these, 90% were screen-time-plus interventions.

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