Rigorous control conditions diminish treatment effects in weight loss-randomized controlled trials.

BACKGROUND: It has not been established whether control conditions with large weight losses (WLs) diminish expected treatment effects in WL or prevention of weight gain (PWG)-randomized controlled trials (RCTs). SUBJECTS/METHODS: We performed a meta-analysis of 239 WL/PWG RCTs that include a control group and at least one treatment group. A maximum likelihood meta-analysis framework was used to model and understand the relationship between treatment effects and control group outcomes. RESULTS: Under the informed model, an increase in control group WL of 1 kg corresponds with an expected shrinkage of the treatment effect by 0.309 kg (95% confidence interval (-0.480, -0.138), P=0.00081); this result is robust against violations of the model assumptions. CONCLUSIONS: We find that control conditions with large WLs diminish expected treatment effects. Our investigation may be helpful to clinicians as they design future WL/PWG studies.

A systematic review and meta-analysis of randomized controlled trials of the impact of sleep duration on adiposity and components of energy balance.

Recent epidemiological and ecological trends in humans indicate a possible causal relationship between sleep duration and energy balance. We aimed to find experimental evidence that has tested this relationship between sleep duration and measures of body composition, food intake or biomarkers related to food intake. We conducted a systematic literature review using six databases throughout 7 August 2014. We sought reports of randomized controlled trials where sleep duration was manipulated and measured outcomes were body weight or other body composition metrics, food intake, and/or biomarkers related to eating. We found 18 unique studies meeting all criteria: eight studies with an outcome of body weight (4 - increased sleep, 4 - reduced sleep); four studies on food intake; four studies of sleep restriction on total energy expenditure and three of respiratory quotient; and four studies on leptin and/or ghrelin. Few controlled experimental studies have addressed the question of the effect of sleep on body weight/composition and eating. The available experimental literature suggests that sleep restriction increases food intake and total energy expenditure with inconsistent effects on integrated energy balance as operationalized by weight change. Future controlled trials that examine the impact of increased sleep on body weight/energy balance factors are warranted.

Predicting adult weight change in the real world: a systematic review and meta-analysis accounting for compensatory changes in energy intake or expenditure.

BACKGROUND: Public health and clinical interventions for obesity in free-living adults may be diminished by individual compensation for the intervention. Approaches to predict weight outcomes do not account for all mechanisms of compensation, so they are not well suited to predict outcomes in free-living adults. Our objective was to quantify the range of compensation in energy intake or expenditure observed in human randomized controlled trials (RCTs). METHODS: We searched multiple databases (PubMed, CINAHL, SCOPUS, Cochrane, ProQuest, PsycInfo) up to 1 August 2012 for RCTs evaluating the effect of dietary and/or physical activity interventions on body weight/composition. INCLUSION CRITERIA: subjects per treatment arm ≥5; ≥1 week intervention; a reported outcome of body weight/body composition; the intervention was either a prescribed amount of over- or underfeeding and/or supervised or monitored physical activity was prescribed; ≥80% compliance; and an objective method was used to verify compliance with the intervention (for example, observation and electronic monitoring). Data were independently extracted and analyzed by multiple reviewers with consensus reached by discussion. We compared observed weight change with predicted weight change using two models that predict weight change accounting only for metabolic compensation. FINDINGS: Twenty-eight studies met inclusion criteria. Overfeeding studies indicate 96% less weight gain than expected if no compensation occurred. Dietary restriction and exercise studies may result in up to 12-44% and 55-64% less weight loss than expected, respectively, under an assumption of no behavioral compensation. INTERPRETATION: Compensation is substantial even in high-compliance conditions, resulting in far less weight change than would be expected. The simple algorithm we report allows for more realistic predictions of intervention effects in free-living populations by accounting for the significant compensation that occurs.

Association of run-in periods with weight loss in obesity randomized controlled trials.

Study-level design characteristics that inform the optimal design of obesity randomized controlled trials (RCTs) have been examined in few studies. A pre-randomization run-in period is one such design element that may influence weight loss. We examined 311 obesity RCTs published between 1 January 2007 and 1 July 2009 that examine d weight loss or weight gain prevention as a primary or secondary end-point. Variables included run-in period, pre-post intervention weight loss, study duration (time), intervention type, percent female and degree of obesity. Linear regression was used to estimate weight loss as a function of (i) run-in (yes/no) and (ii) run-in, time, percent female, body mass index and intervention type. Interaction terms were also examined. Approximately 19% (18.6%) of the studies included a run-in period, with pharmaceutical studies having the highest frequency. Although all intervention types were associated with weight loss (Mean = 2.80 kg, SD = 3.52), the inclusion of a pre-randomization run-in was associated with less weight loss (P = 0.0017) compared with studies that did not include a run-in period. However, this association was not consistent across intervention types. Our results imply that in trials primarily targeting weight loss in adults, run-in periods may not be beneficial for improving weight loss outcomes in interventions.

Will reducing sugar-sweetened beverage consumption reduce obesity? Evidence supporting conjecture is strong, but evidence when testing effect is weak.

We provide arguments to the debate question and update a previous meta-analysis with recently published studies on effects of sugar-sweetened beverages (SSBs) on body weight/composition indices (BWIs). We abstracted data from randomized controlled trials examining effects of consumption of SSBs on BWIs. Six new studies met these criteria: (i) human trials, (ii) ≥ 3 weeks duration, (iii) random assignment to conditions differing only in consumption of SSBs and (iv) including a BWI outcome. Updated meta-analysis of a total of seven studies that added SSBs to persons' diets showed dose-dependent increases in weight. Updated meta-analysis of eight studies attempting to reduce SSB consumption showed an equivocal effect on BWIs in all randomized subjects. When limited to subjects overweight at baseline, meta-analysis showed a significant effect of roughly 0.25 standard deviations (more weight loss/less weight gain) relative to controls. Evidence to date is equivocal in showing that decreasing SSB consumption will reduce the prevalence of obesity. Although new evidence suggests that an effect may yet be demonstrable in some populations, the integrated effect size estimate remains very small and of equivocal statistical significance. Problems in this research area and suggestions for future research are highlighted.

Getting carried away: a note showing baseline observation carried forward (BOCF) results can be calculated from published complete-cases results.

OBJECTIVE: Randomized controlled trials (RCTs) in obesity are plagued by missing data due to participant dropouts. Most methodologists and regulatory bodies agree that the primary analysis of such RCTs should be based on the intent-to-treat (ITT) principle, such that all randomized subjects are included in the analysis, even those who dropped out. Unfortunately, some authors do not include an ITT analysis in their published reports. Here we show that one form of ITT analysis, baseline observation carried forward (BOCF), can be performed utilizing only information available in a published complete-case (CC) analysis, permitting readers, editors, meta-analysts and regulators to easily conduct their own ITT analyses when the original authors do not report one. METHOD: We mathematically derive a simple method for estimating and testing treatment effects using the BOCF to allow a more conservative comparison of treatment effects when there are dropouts in a clinical trial. We provide two examples of this method using available CC analysis data from reported obesity trials to illustrate the application for readers who wish to determine a range of treatment effects based on published summary statistics. CONCLUSION: Commonly used CC analyses may lead to inflated type I error rates and/or treatment effect estimates. The method described herein can be useful for researchers who wish to estimate a conservative range of plausible treatment effects based on limited reported data. Limitations of this method are discussed.

Is funding source related to study reporting quality in obesity or nutrition randomized control trials in top-tier medical journals?

BACKGROUND: Faithful and complete reporting of trial results is essential to the validity of the scientific literature. An earlier systematic study of randomized controlled trials (RCTs) found that industry-funded RCTs appeared to be reported with greater quality than non-industry-funded RCTs. The aim of this study was to examine the association between systematic differences in reporting quality and funding status (that is, industry funding vs non-industry funding) among recent obesity and nutrition RCTs published in top-tier medical journals. METHODS: Thirty-eight obesity or nutrition intervention RCT articles were selected from high-profile, general medical journals (The Lancet, Annals of Internal Medicine, JAMA and the British Medical Journal) published between 2000 and 2007. Paired papers were selected from the same journal published in the same year, one with and the other without industry funding. The following identifying information was redacted: journal, title, authors, funding source and institution(s). Then three raters independently and blindly rated each paper according to the Chalmers method, and total reporting quality scores were calculated. FINDINGS: The inter-rater reliability (Cronbach's alpha) was 0.82 (95% confidence interval = 0.80-0.84). The total mean (M) and s.d. of Chalmers Index quality score (out of a possible 100) for industry-funded studies were M = 84.5, s.d. = 7.04 and for non-industry-funded studies they were M = 79.4, s.d. = 13.00. A Wilcoxon matched-pairs signed-ranks test indicates no significant rank difference in the distributions of total quality scores between funding sources, Z = -0.966, P = 0.334 (two tailed). INTERPRETATION: Recently published RCTs on nutrition and obesity that appear in top-tier journals seem to be equivalent in quality of reporting, regardless of funding source. This may be a result of recent reporting of quality statements and efforts of journal editors to raise all papers to a common standard.

Nutritively sweetened beverage consumption and body weight: a systematic review and meta-analysis of randomized experiments.

Nutritively sweetened beverages (NSBs) may play a role in the obesity epidemic. We abstracted data from randomized controlled trials (RCTs) and evidence-based reviews through January 2009 concerning effects of consumption of NSBs on changes in body weight and adiposity. Studies included were those (i) conducted in humans; (ii) lasting at least 3 weeks; (iii) incorporating random assignment of subjects to conditions that differed only in the consumption of NSBs and (iv) including an adiposity indicator as an outcome. Twelve studies met the inclusion criteria. Meta-analysis of six studies that added NSBs to persons' diets showed dose-dependent increases in weight. Contrarily, meta-analysis of studies that attempted to reduce NSB consumption consistently showed no effect on body mass index (BMI) when all subjects were considered. Meta-analysis of studies providing access to results separately for subjects overweight at baseline showed a significant effect of a roughly 0.35 standard deviations lesser BMI change (i.e. more weight loss or less weight gain) relative to controls. The current evidence does not demonstrate conclusively that NSB consumption has uniquely contributed to obesity or that reducing NSB consumption will reduce BMI levels in general. We recommend an adequately powered RCT with overweight persons, for whom there is suggestive evidence of an effect.

The effect of an interactive experience on music majors' perceptions of music for deaf students.

The purpose of this study was to examine the effect of an interactive experience on music majors' perceptions of music experiences for deaf students. Twenty-three members of a pre-existing college brass ensemble served as subjects, and a 1-hour interactive concert/presentation for 10 deaf elementary children served as the independent variable. The interactive experience was designed to provide social, musical, and educational interactions between the college musicians and the deaf children. A pretest-posttest design was utilized, and the dependent variable was a questionnaire designed to examine the subjects' perceptions regarding music for deaf students, including how prepared, comfortable, and willing they felt to provide music experiences for deaf students. Results reveal that this single interactive experience had a significant effect on the subjects' perceptions of the value of music in the education of deaf children (p <.05). Although the pretest and posttest scores indicate that the subjects felt apprehensive about their preparedness to work with deaf students, the subjects felt significantly more positive about their preparedness following the interaction (p <.001). An analysis of open comments indicates that the subjects perceived the experience as (a) very positive, (b) increasing their knowledge and perception of music for deaf students, (c) helping them better relate to the deaf population, (d) promoting interest in similar experiences and in gaining more information, and (e) eliciting a feeling that future teachers should have similar experiences. Quotes from the subjects are given, and implications for teacher training/music therapy programs are discussed.