EAL

NGHC: Prevention of Chronic Disease (2013)

Citation:

Forshee RA, Anderson PA, Storey ML. Sugar-sweetened beverages and body mass index in children and adolescents: a meta-analysis. Am J Clin Nutr. 2008 Jun;87(6):1662-71. Erratum in: Am J Clin Nutr. 2009 Jan;89(1):441-2.

PubMed ID: 18541554

Study Design:

Meta-analysis or Systematic Review

Class:

M - Click here for explanation of classification scheme.

Quality Rating:

NEUTRAL: See Quality Criteria Checklist below.

Research Purpose:

The purpose of this meta-analysis was to determine whether the results of the original research that used longitudinal and randomized controlled trials (RCTs) support the hypothesis that sugar-sweetened beverage (SB) consumption is associated with increased BMI among children and adolescents and, if so, to determine the magnitude of the effect.

Inclusion Criteria:

English-language articles
Published between 1966-October 2006
Studied sugar-sweetened beverages (soft drinks and fruit drinks or ades) and BMI, weight gain, and/or obesity
Studied human subjects < 19 years of age

Exclusion Criteria:

Ecological and cross-sectional studies

Description of Study Protocol:

Recruitment: The MEDLINE database was used to identify relevant studies that met inclusion/exclusion criteria. Guidance from the MeSH terms database identified the following search terms: "beverages obesity," "beverages BMI," "soft drinks obesity," "soft drinks BMI," "sweetened drinks," and "sugar drink fat mass." The bibliographies from 5 review articles were also checked to ensure that all relevant articles were captured.

Statistical Analysis

For some studies it was necessary to apply scaling factors to express the results in terms of change (Δ) in BMI units per 12-oz serving Δ sugar-sweetened beverage.
Coefficients and standard errors were extracted from the studies and compiled into a statistical database in STATA software. When standard errors were not reports, they were calculated based on CIs or P values.
Results were analyzed by using the METAN:STATA module for fixed- and random-effects meta-analysis program. Forest plots show the estimated effect size, CI, and the precision of each study in the meta-analysis. Estimates of the overall pooled relation and SE were calculated with the use of both fixed-effects and random-effects models. Test statistics indicated heterogeneity in the results from the studies in the meta-analysis, so the random-effects estimates are more appropriate.
META-FUNNEL was used to produce funnel plots.
METAINF: Stata module was used to evaluate the influence of a single study in meta-analysis estimation to test for particularly influential studies.

Data Collection Summary:

Dependent Variables

Change (Δ) in BMI units

Independent Variables

12 oz serving Δ in sugar-sweetened beverages

Description of Actual Data Sample:

Initial N: A total of 12 (10 longitudinal and 2 RCT) were reviewed for this meta-analysis.

Attrition (final N): Eight of the longitudinal studies and both RCT studies were incorporated into the quantitative meta-analysis. The remaining studies did not provide the necessary information for the quantitative meta-analysis.

Summary of Results:

The meta-analysis results estimated a 0.3 (95% CI: 0.01,0.07) BMI unit change per serving of of sugar-sweetened beverage (12 oz serving), which is not significant.

Other Findings

No single study had a large influence on the overall results.
The funnel plot for these studies shows that the studies with precise estimates are tightly and symmetrically groups around the average affect size (indicating a bias against publishing studies that do not show statistically significant results).

Author Conclusion:

The authors conclude that the results of this study suggest that their is no effect of sugar-sweetened beverage consumption on body weight in children and adolescents.

Reviewer Comments:

This study was funded by the American Beverage Association.

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)	N/A
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	N/A
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	N/A
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	N/A

Validity Questions
1.	Was the research question clearly stated?		N/A
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	N/A
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	N/A
	1.3.	Were the target population and setting specified?	N/A
2.	Was the selection of study subjects/patients free from bias?		N/A
	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?	N/A
	2.2.	Were criteria applied equally to all study groups?	N/A
	2.3.	Were health, demographics, and other characteristics of subjects described?	N/A
	2.4.	Were the subjects/patients a representative sample of the relevant population?	N/A
3.	Were study groups comparable?		N/A
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	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?		N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	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%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	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?		N/A
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	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.)	N/A
	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?		N/A
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	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?	N/A
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	N/A
	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?		N/A
	7.1.	Were primary and secondary endpoints described and relevant to the question?	N/A
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	N/A
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	N/A
	7.5.	Was the measurement of effect at an appropriate level of precision?	N/A
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	N/A
	7.7.	Were the measurements conducted consistently across groups?	N/A
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		N/A
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	N/A
	8.2.	Were correct statistical tests used and assumptions of test not violated?	N/A
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	N/A
	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)?	N/A
	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?		N/A
	9.1.	Is there a discussion of findings?	N/A
	9.2.	Are biases and study limitations identified and discussed?	N/A
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