EAL

PWM: Physical Activity and Inactivity (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Provide another test of the hypothesis that decreasing sedentary behaviors produces equal or better weight loss and fitness change than increasing physical activity when included as part of a comprehensive pediatric obesity intervention.
Test whether there is a dose-response relationship between the amount of reduction in sedentary behaviors and weight loss and fitness outcomes.

Inclusion Criteria:

Families with children ages 8-12 years between 20% and 100% overweight,
neither parent more than 100% overweight, 1
parent willing to attend treatment meetings,
no family member participating in an alternative weight control program,
no parent or child with current psychiatric problems,
no dietary or exercise restrictions on the participating parent or child

Exclusion Criteria:

No additional.

Description of Study Protocol:

Children and parents recruited in 2 cohorts that began 1 year apart through physician referrals, posters, and newspaper and television advertisements. Families were stratified by sex and randomly assigned to 1 of 4 groups that varied targeted behaviors (sedentary behaviors vs physical activity) and treatment dose (low vs high, with low 10 hours/week of targeted sedentary behaviors or equivalent energy expenditure of 10 mi/week and high 20 hours/week or 20 mi/week).

6 month treatment included 16 weekly meetings, followed by 2 biweekly and 2 monthly meetings. Families seen at 12 and 24 months for follow-up.

Parent and child workbooks included introduction to weight control and self monitoring, activity program, behavior change techniques. At treatment meetings participants were weighed, met with individual therapist 15-30 minutes (review of weekly weight change, diet, targeted activities, behavioral contract), attended separate 30 minute parent and child group meetings.

Traffic light diet was used to decrease energy intake – children and overweight parents instructed to consume 4184-5021 kJ/d and limit red foods to 10 or fewer per week and eat servings based on food pyramid. When weight decreased to nonobese range, participants instructed to develop maintenance calorie level. Nonoverweight parents had no caloric restriction, just asked to limit red foods. Additional nutritional information provided, preplanning taught to facilitate decision making.

Parents and children taught positive reinforcement techniques.

Parents deposited $75 to be returned contingent on completing 75% of treatment sessions and attending month 6 and 12 follow-up. Families were paid $50 for attendance at 24 month follow up.

Participants assigned to increase physical activity group were reinforced for increasing physical activities in addition to those engaged in at program onset. Participants assigned to decrease sedentary activity group were reinforced for reducing sedentary behaviors that compete with being active or set occasion for eating. Not all sedentary activities targeted (eg homework), so participants could substitute nontargeted sedentary activities for targeted ones.

Data Collection Summary:

Dependent

Collected at baseline and at months 6, 12, 24):

height (measured in 1/8 in intervals using stadiometer, self reported and adjusted if unable to attend assessments);
weight (0.25 lb increments using balance beam scale);
BMI (calculated and compared with population standards based on sex and age; Must 1991);
percent overweight (comparing BMI to 50^th percentile BMI based on sex and age; Must 1991);
percent body fat (bioelectrical impedance);
fat free body mass (kg, based on weight and percent body fat);
fitness (heart rate monitor during increasing workloads on ergometer);
physical work capacity (kilopond meters/min based on heart rate and workload);
maximal oxygen consumption (estimated based on heart rate, workload, fat free mass);
frequency and time spent on physical activity (questionnaire based on Minnesota Leisure Time Activity Survey, 39 activities);
SES (Hollingshead Index).

Independent

targeted behaviors (sedentary behaviors vs physical activity);
treatment dose (low vs high).

Control Variables

Statistical Analysis

1 way analysis of variance to assess group differences at baseline; mixed ANOVA to assess treatment effects for body composition and fitness; mixed ANOVA to analyze changes in percent time in physically active and targeted and nontargeted sedentary behaviors from baseline to 6 and 24 months after treatment.

Description of Actual Data Sample:

Original Sample: 461 families interested in participation, 171 families screened, 90 families randomized.

Withdrawals/Drop-Outs:

Increase activity/low dose group (n=22): 4 did not attend 2 year follow ups.
Increase activity/high dose group (n=23): 2 withdrew during treatment, 2 did not attend 2 year follow ups.
Decrease sedentary/low dose group (n=23): 4 did not attend 2 year follow ups.
Decrease sedentary/high dose group (n=22): 2 did not attend 2 year follow up.

Final Sample:

76 children (24M, 52F) and parents (16M, 58F) completed trial.

Location: childhood obesity research clinic, location not specified (assumed Buffalo, NY)

Race/Ethnicity: Not specified.

SES: mean Hollingshead Index 47.5 +/- 10.1 for final sample.

Summary of Results:

No significant baseline group differences for anthropometric, body composition, fitness, activity data. 64% of 76 parents were obese (obesity defined as BMI greater than 85^th percentile). No differential attrition across 4 treatment groups from baseline to 2 year assessment (p=.73).

Significant decreases in percent overweight observed from baseline to 6 months through 2 years (p<.001).

Percent overweight decrease of 25.5% at end of treatment across groups. At 24 months percent overweight decrease was 12.9%. Intent to treat analysis showed decrease in percent overweight of 22.7% at 6 months and 10.9% at 2 years (p<.001).

Physical work capacity improved significantly with increases of 33% at 6 months and 55% at 24 months (p<.001).

Significant decreases observed for percent body fat – 6.4% decrease at 6 months, 2.0% decrease at 24 months (p<.001). No significant differences in rate of change by group were observed for any anthropometric or fitness measure.

Significant increase in percent time being active observed at 2 years (p<.05). Targeted sedentary behaviors showed significant decrease at 6 months (p<.001) and 24 months (p<.05). Nontargeted sedentary behaviors increased from baseline to 6 months (p<.05).

Obese parents who completed the trial showed significant decreases in weight (p<.001) at 6 months through 2 years; parents lost 12.0kg at 6 months and 7.1kg at 2 years (decrease of 7.8%).

Author Conclusion:

Results provide evidence that reducing access to sedentary behaviors is an alternative to targeting physical activity in the treatment of childhood obesity. Both approaches were associated with similar decreases in percent overweight and increases in fitness.

Significant increases were observed in physical activity and significant decreases in targeted sedentary time.

Reducing access to sedentary behaviors may be effective when there are a wide variety of acceptable physically active alternatives available.

No differences in percent overweight or fitness change were observed for children randomized to decrease targeted sedentary behaviors to no more than 10 or 20 hours per week. Reducing targeted sedentary behaviors to 20 hours/wk makes sufficient leisure time available, further reductions in sedentary behavior to 10 hours/wk may not result in further increases in physical activity. It is also possible that while groups were designed to be implemented at different doses, this may not have been accomplished. It is also possible that as dose increases, may be harder to comply with treatment recommendations, reducing differences between groups.

May be interesting to determine if there are specific types of sedentary behaviors that compete with being physically active.

Caloric intake was not measured, and decreasing sedentary behaviors can reduce opportunities for eating and thus make an important contribution to facilitating dietary adherence and caloric reduction.

Reducing sedentary behaviors as part of a comprehensive family based weight control program is associated with similar weight, fitness, and psychological changes in comparison to a well validated program to increase physical activity in children, This increases the flexibility of those who are treating obese children.

Funding Source:

Government:

National Institute for Child Health and Human Development

Reviewer Comments:

Weaknesses:

No control used (no “diet only, no physical activity” group, so unable to contrast normal changes that might occur when physical activity or sedentary behaviors are not targeted in any way).

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		Yes
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	No
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	Yes
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	No
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		No
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	???
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	No
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	No
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	Yes
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	N/A
	8.6.	Was clinical significance as well as statistical significance reported?	N/A
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes