The dose of behavioral interventions to prevent and treat childhood obesity: a systematic review and meta-regression

Abstract

Background: A better understanding of the optimal "dose" of behavioral interventions to affect change in weight-related outcomes is a critical topic for childhood obesity intervention research. The objective of this review was to quantify the relationship between dose and outcome in behavioral trials targeting childhood obesity to guide future intervention development.

Methods: A systematic review and meta-regression included randomized controlled trials published between 1990 and June 2017 that tested a behavioral intervention for obesity among children 2-18 years old. Searches were conducted among PubMed (Web-based), Cumulative Index to Nursing and Allied Health Literature (EBSCO platform), PsycINFO (Ovid platform) and EMBASE (Ovid Platform). Two coders independently reviewed and abstracted each included study. Dose was extracted as intended intervention duration, number of sessions, and length of sessions. Standardized effect sizes were calculated from change in weight-related outcome (e.g., BMI-Z score).

Results: Of the 258 studies identified, 133 had sufficient data to be included in the meta-regression. Average intended total contact (# sessions x length of sessions) was 27.7 (SD 32.2) hours and average duration was 26.0 (SD 23.4) weeks. When controlling for study covariates, a random-effects meta-regression revealed no significant association between contact hours, intended duration or their interaction and effect size.

Conclusions: This systematic review identified wide variation in the dose of behavioral interventions to prevent and treat pediatric obesity, but was unable to detect a clear relationship between dose and weight-related outcomes. There is insufficient evidence to provide quantitative guidance for future intervention development. One limitation of this review was the ability to uniformly quantify dose due to a wide range of reporting strategies. Future trials should report dose intended, delivered, and received to facilitate quantitative evaluation of optimal dose.

Trial registrations: The protocol was registered on PROSPERO (Registration # CRD42016036124 ).

Keywords: Behavioral intervention; Childhood obesity; Dose; Health behavior; Systematic review.

Fig. 1

Flow Diagram

Fig. 2

Assessment of Study Quality using the Delphi Criteria. The percent of studies adhering to the Delphi criteria is shown, comparing studies included in the analytic sample vs. studies excluded from the analytic sample. It is important to note that if a study did not specifically report adherence, then the study would be coded as non-adherent

Fig. 3

Box Plot of Standardized Effect Size by Dose Components. For each category of duration (0–14 weeks, 15–26 weeks, over 26 weeks) the standardized effect sizes are shown for each category of contact hours (<10 h, 10–36 h, over 36 h). There does not appear to be a trend by duration or contact hours that would suggest an association between either component and effect size. Note that this approach does not take into account the weighting of studies that is possible through meta-regression techniques. A negative standardized effect size represents a decrease in weight-related outcome and a positive standardized effect size represents an increase in weight-related outcome

Fig. 4

Funnel Plot of Standardized Effect Sizes. The funnel plot demonstrates minimal visual asymmetry, in the direction of excess small studies that resulted in a “negative” outcome (i.e., weight gain = positive effect size). This is supported by the estimated bias coefficient from the Egger test (bias = 1.6, p = 0.03, shown as red solid line). Dotted lines represent the pseudo-95% confidence interval