Analyzing weight loss intervention studies with missing data: which methods should be used?

Testing reward processing models of obesity using in-the-moment assessments of subjective enjoyment of food and non-food activities

OBJECTIVE

Although altered reward processing is proposed to play a key role in obesity maintenance, the role of food enjoyment and enjoyment of non-food naturally rewarding activities ("non-food enjoyment") in obesity maintenance remains unknown. This study examined how food and non-food enjoyment were associated with baseline body mass index (BMI) and weight loss (WL) following year-long behavioral WL treatment.

METHODS

At baseline, participants (MAge = 51.81; 73.8 % White, N = 279) with overweight/obesity completed a 7-day ecological momentary assessment (EMA) protocol inquiring about pleasure/enjoyment derived from eating and non-food activities over the past few hours. Participants also completed retrospective self-report measures of food/non-food enjoyment. With linear regressions, associations between EMA food/non-food enjoyment and BMI and post-treatment WL were examined. Race was included as a covariate.

RESULTS

EMA and retrospective food/non-food enjoyment measures had modest concordance, providing preliminary psychometric support for the EMA measures. Partially consistent with hypotheses, greater EMA food enjoyment was associated with lower BMI (B = -1.03, p = .01) and with greater WL, though the latter association was not statistically significant (B = 1.15, p = .07). Exploratory analyses suggested that race was associated with food enjoyment (non-White participants had greater food enjoyment than White participants, d = 0.81, p = .005), and that race may have affected associations between food enjoyment and weight outcomes. Associations between non-food enjoyment and weight outcomes were small and nonsignificant (ps > .93).

CONCLUSIONS

Results suggest enjoyment from food, but not from non-food domains, is associated with weight outcomes.

Predictors of long-term return-to-work at five-year follow-up for mild-to-moderate subacute stroke patients enrolled in an early supported discharge program

BACKGROUND: Facilitating return-to-work (RTW) for working-age stroke survivors is a key component of stroke rehabilitation, however, research investigating the long-term outcomes of working-age stroke survivors is lacking. OBJECTIVE: To investigate the factors that influence long-term RTW for patients enrolled on a community-based early supported discharge (ESD) rehabilitation program in Singapore about five years post stroke. METHODS: Sixty-nine patients, aged between 18 and 60 years and were employed at the time of their hospitalization, were enrolled into the ESD program between 2012 and 2014. A prospective cohort design was adopted to examine the relationships between the factors— demographic, functional, personal, psychosocial factors and work related— and RTW at five-year follow-up. Details of RTW were collected through questionnaires via telephone follow-up. RESULTS: Sixty percent of the participants (n = 49) were selected for Cox and logistic regression analyses of RTW at five-year follow-up. The results indicated that having social problems is a negative predictor of RTW (OR 0.02; 95% CI 0.00–0.22) while being the breadwinner is a positive predictor of RTW (OR 13.79; 95% CI 2.46–77.52). The same factors were also significant in the time to RTW event at five-year follow-up, with a hazard ratio of 0.09 and 4.07, respectively. CONCLUSIONS: Early identification of the characteristics of stroke patients enrolled into an ESD program who have the potential to RTW would make interventions more targeted, increasing the likelihood of RTW.

Beyond Calorie Tracking: A Pilot Trial of a Remotely Delivered Behavioral Weight Loss Intervention Using an Ad Libitum Plant-Based Diet (Preprint)

Background

Many traditional lifestyle interventions use calorie prescriptions, but most individuals have difficulty sustaining calorie tracking and thus weight loss. In contrast, whole food plant-based diets (WFPBDs) have previously shown significant weight loss without this issue. However, most WFPBD interventions are face-to-face and time-intensive, and do not leverage gold standard behavioral strategies for health behavior change.

Objective

This open pilot trial was the first to evaluate the feasibility of a fully featured, remotely delivered behavioral weight loss intervention using an ad libitum WFPBD.

Methods

Over 12 weeks, participants (N=15) with overweight or obesity received a newly designed program that integrated behavioral weight loss and a WFPBD prescription via weekly web-based modules and brief phone coaching calls. Assessments were performed at baseline, midtreatment (6 weeks), and after treatment (12 weeks).

Results

The intervention was rated as highly acceptable (mean 4.40 out of 5, SE 0.18), and attrition was low (6.7%). In all, intention-to-treat analyses revealed that 69% (10.4/15) of the participants lost 5% of their weight (mean –5.89, SE 0.68 kg). Predefined benchmarks for quality of life were met.

Conclusions

A pilot digital behavioral weight loss intervention with a non–energy-restricted WFPBD was feasible, and the mean acceptability was high. Minimal contact time (80-150 minutes of study interventionist time per participant over 12 weeks) led to clinically relevant weight loss and dietary adherence for most participants (10.4/15, 69% and 11.8/15, 79%, respectively), and quality of life improvements (reliable change indices >1.53). We hope that this work will serve as a springboard for future larger scale randomized controlled studies evaluating the efficacy of such programs for weight loss, dietary change, and quality of life.

Trial Registration

ClinicalTrials.gov NCT04892030; https://clinicaltrials.gov/ct2/show/NCT04892030

A randomised controlled trial of the 5:2 diet

Objective

The 5:2 diet is a popular intermittent energy restriction method of weight management that awaits further evaluation. We compared the effects of one-off 5:2 instructions with the effects of one-off standard multicomponent weight-management advice; and also examined whether additional behavioural support enhances 5:2 adherence and efficacy compared to one-off instructions.

Methods

Three hundred adults with obesity were randomised to receive a Standard Brief Advice (SBA) covering diet and physical activity (N = 100); 5:2 self-help instructions (5:2SH) (N = 100); or 5:2SH plus six once-weekly group support sessions (N = 100). Participants were followed up for one year.

Results

Adherence to 5:2SH was initially high (74% at 6 weeks), but it declined over time (31% at 6 months and 22% at one year). 5:2SH and SBA achieved similar weight-loss at six months (-1.8kg (SD = 3.5) vs -1.7kg (SD = 4.4); b = 0.23, 95%CI:-0.79–1.27, p = 0.7) and at one year (-1.9kg (SD = 4.9) vs -1.8kg (SD = 5.7), b = 0.20, 95%CI:-1.21–1.60, p = 0.79), with 18% vs 15% participants losing ≥5% of their body weight with 5:2SH and SBA, respectively at one year (RR = 0.83, 95%CI:0.44–1.54, p = 0.55). Both interventions received positive ratings, but 5:2SH ratings were significantly higher. 5:2SH had no negative effect on fat and fiber intake and physical activity compared to SBA. Compared to 5:2SH, 5:2G generated a greater weight loss at 6 weeks (-2.3kg vs -1.5kg; b = 0.74, 95%CI:1.37–0.11, p = 0.02), but by one year, the difference was no longer significant (-2.6kg vs -1.9kg, p = 0.37; ≥5% body weight loss 28% vs 18%, p = 0.10).

Conclusions

Simple 5:2 advice and multicomponent weight management advice generated similar modest results. The 5:2 diet did not undermine other health behaviours, and it received more favourable ratings. Adding initial group support enhanced 5:2 adherence and effects, but the impact diminished over time. Health professionals who provide brief weight management advice may consider including the 5:2 advice as an option.

Trial registration

ISRCTN registry (ISRCTN79408248).

Impact of missing outcome data in meta-analyses of lifestyle interventions during pregnancy to reduce postpartum weight retention: An overview of systematic reviews with meta-analyses and additional sensitivity analyses

High risk of bias associated with missing outcome data (MOD) in meta-analyses (MAs) of the effects of lifestyle interventions during pregnancy on postpartum weight retention (PPWR) casts doubt on whether such interventions can be relied upon as truly effective. This systematic overview of three MAs (19 RCTs), each with high MOD rates in the subset of RCTs included, examined how MOD were addressed in the estimation of summary intervention effects. All MAs reported beneficial and statistically significant intervention effects estimated based on complete case analyses, deemed valid if MOD was missing at random (MAR). Therefore, we conducted sensitivity analyses using pattern mixture models and informative missingness parameters (describing how the outcome in the missing participants may be related to the outcome in the completers), to ascertain the robustness of the estimates to reasonable deviations from the MAR assumption. In plausible scenarios where the response in intervention group participants with versus without MOD was worse (by just 0.5 kg), effect estimates were attenuated in all MAs and no longer statistically significant in two MAs. Statistical significance was retained when all 19 RCTs identified across MAs were examined together in a broader meta-analysis: -0.63 kg (95%CI -0.17, -0.08), but the clinical relevancy of effects of this magnitude remains unclear.

Examining weight suppression as a predictor and moderator of intervention outcomes in an eating disorder and obesity prevention trial: A replication and extension study

Weight suppression (WS) predicts future weight gain and increases in eating disorder symptoms in community and clinical samples but has received minimal attention in obesity and eating disorder prevention programs. In a sample of emerging adults (N = 364) in a randomized controlled trial evaluating two obesity and eating disorder prevention interventions versus a control condition, this study aimed to replicate the findings that WS and its interaction with baseline BMI predict increases in weight and eating disorder symptoms and test a novel hypothesis that WS would moderate the effects of the interventions on change in weight and eating disorder symptoms. Participants completed assessments at baseline, post-intervention, 6-, 12-, and 24-months. WS was calculated as the difference between highest lifetime weight and baseline weight. WS interacted with baseline BMI to predict greater weight gain over 24-months, such that those with high WS and lower baseline BMI gained weight most rapidly. WS did not predict eating disorder symptom change and did not moderate the effects of the prevention programs. Given that individuals with WS are at increased risk for weight gain, expressly targeting this high-risk population with evidence-based obesity prevention programs may be useful. CLINICALTRIALS.GOV REGISTRATION: NCT01680224.

Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data

OBJECTIVE

To determine the efficacy and safety of low carbohydrate diets (LCDs) and very low carbohydrate diets (VLCDs) for people with type 2 diabetes.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Searches of CENTRAL, Medline, Embase, CINAHL, CAB, and grey literature sources from inception to 25 August 2020.

STUDY SELECTION

Randomized clinical trials evaluating LCDs (<130 g/day or <26% of a 2000 kcal/day diet) and VLCDs (<10% calories from carbohydrates) for at least 12 weeks in adults with type 2 diabetes were eligible.

DATA EXTRACTION

Primary outcomes were remission of diabetes (HbA1c <6.5% or fasting glucose <7.0 mmol/L, with or without the use of diabetes medication), weight loss, HbA1c, fasting glucose, and adverse events. Secondary outcomes included health related quality of life and biochemical laboratory data. All articles and outcomes were independently screened, extracted, and assessed for risk of bias and GRADE certainty of evidence at six and 12 month follow-up. Risk estimates and 95% confidence intervals were calculated using random effects meta-analysis. Outcomes were assessed according to a priori determined minimal important differences to determine clinical importance, and heterogeneity was investigated on the basis of risk of bias and seven a priori subgroups. Any subgroup effects with a statistically significant test of interaction were subjected to a five point credibility checklist.

RESULTS

Searches identified 14 759 citations yielding 23 trials (1357 participants), and 40.6% of outcomes were judged to be at low risk of bias. At six months, compared with control diets, LCDs achieved higher rates of diabetes remission (defined as HbA1c <6.5%) (76/133 (57%) v 41/131 (31%); risk difference 0.32, 95% confidence interval 0.17 to 0.47; 8 studies, n=264, I2=58%). Conversely, smaller, non-significant effect sizes occurred when a remission definition of HbA1c <6.5% without medication was used. Subgroup assessments determined as meeting credibility criteria indicated that remission with LCDs markedly decreased in studies that included patients using insulin. At 12 months, data on remission were sparse, ranging from a small effect to a trivial increased risk of diabetes. Large clinically important improvements were seen in weight loss, triglycerides, and insulin sensitivity at six months, which diminished at 12 months. On the basis of subgroup assessments deemed credible, VLCDs were less effective than less restrictive LCDs for weight loss at six months. However, this effect was explained by diet adherence. That is, among highly adherent patients on VLCDs, a clinically important reduction in weight was seen compared with studies with less adherent patients on VLCDs. Participants experienced no significant difference in quality of life at six months but did experience clinically important, but not statistically significant, worsening of quality of life and low density lipoprotein cholesterol at 12 months. Otherwise, no significant or clinically important between group differences were found in terms of adverse events or blood lipids at six and 12 months.

CONCLUSIONS

On the basis of moderate to low certainty evidence, patients adhering to an LCD for six months may experience remission of diabetes without adverse consequences. Limitations include continued debate around what constitutes remission of diabetes, as well as the efficacy, safety, and dietary satisfaction of longer term LCDs.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020161795.

Intermittent fasting, Paleolithic, or Mediterranean diets in the real world: exploratory secondary analyses of a weight-loss trial that included choice of diet and exercise

BACKGROUND

Intermittent fasting (IF) and Paleolithic (Paleo) diets produce weight loss in controlled trials, but minimal evidence exists regarding long-term efficacy under free-living conditions without intense dietetic support.

OBJECTIVES

This exploratory, observational analysis examined adherence, dietary intake, weight loss, and metabolic outcomes in overweight adults who could choose to follow Mediterranean, IF, or Paleo diets, and standard exercise or high-intensity interval training (HIIT) programs, as part of a 12-mo randomized controlled trial investigating how different monitoring strategies influenced weight loss (control, daily self-weighing, hunger training, diet/exercise app, brief support).

METHODS

A total of 250 overweight [BMI (in kg/m2) ≥27] healthy adults attended an individualized dietary education session (30 min) relevant to their self-selected diet. Dietary intake (3-d weighed diet records), weight, body composition, blood pressure, physical activity (0, 6, and 12 mo), and blood indexes (0 and 12 mo) were assessed. Mean (95% CI) changes from baseline were estimated using regression models. No correction was made for multiple tests.

RESULTS

Although 54.4% chose IF, 27.2% Mediterranean, and 18.4% Paleo diets originally, only 54% (IF), 57% (Mediterranean), and 35% (Paleo) participants were still following their chosen diet at 12 mo (self-reported). At 12 mo, weight loss was -4.0 kg (95% CI: -5.1, -2.8 kg) in IF, -2.8 kg (-4.4, -1.2 kg) in Mediterranean, and -1.8 kg (-4.0, 0.5 kg) in Paleo participants. Sensitivity analyses showed that, due to substantial dropout, these may be overestimated by ≤1.2 kg, whereas diet adherence increased mean weight loss by 1.1, 1.8, and 0.3 kg, respectively. Reduced systolic blood pressure was observed with IF (-4.9 mm Hg;  -7.2, -2.6 mm Hg) and Mediterranean (-5.9 mm Hg; -9.0, -2.7 mm Hg) diets, and reduced glycated hemoglobin with the Mediterranean diet (-0.8 mmol/mol; -1.2, -0.4 mmol/mol). However, the between-group differences in most outcomes were not significant and these comparisons may be confounded due to the nonrandomized design.

CONCLUSIONS

Small differences in metabolic outcomes were apparent in participants following self-selected diets without intensive ongoing dietary support, even though dietary adherence declined rapidly. However, results should be interpreted with caution given the exploratory nature of analyses. This trial was registered with the Australian New Zealand Clinical Trials Registry as ACTRN12615000010594 at https://www.anzctr.org.au.

Occupationally Tailored, Web-Based, Nutrition and Physical Activity Program for Firefighters: Cluster Randomized Trial and Weight Outcome

OBJECTIVE

The aim of this study was to determine the efficacy of an occupationally tailored, web-based health and wellness program, The First Twenty® (TF20), for weight change among volunteer firefighters.

METHODS

The impact of TF20 on firefighters' 6-month weight change was tested in a cluster, randomized controlled trial, using a crossover design of firefighters in 10 departments. TF20 has web-based nutrition, physical activity, and behavioral health components.

RESULTS

An adjusted treatment-induced weight loss from 1.7 to 2.8 lb was observed for all participants and 2.3 to 3.1 lb among overweight and obese participants. An average weight gain was observed among firefighters in the control condition and weight loss for those in the treatment condition.

CONCLUSIONS

TF20 supports firefighters' weight loss. Firefighters need wellness interventions to improve nutrition and physical activity given their high prevalence of obesity.

Randomized controlled trial protocol: A quanti-quali approach for analyzing the results of an intervention on the waiting list for bariatric surgery

ABSTRACT Objective This article aims to describe the protocol of a randomized clinical trial and the baseline results of the study of a one-year interdisciplinary intervention in users of the public health system in the bariatric surgery waiting list. Methods A randomized, single-blind clinical trial will be conducted including 88 participants recruited on an outpatient clinic of the public health system. Participants were randomized into the control group (n=44), receiving the usual treatment; and into the intervention group (n=44), participating in the educational intervention. Participants had their food intake, negative affectivity and physical inactivity/sedentary behavior assessed, as well as anthropometric and body composition measurements; their blood samples were collected; and also had different physical capacity tests. Results Of the 157 participants invited, 27 had severe functional limitations, one was under-age, and four declined the study due to associated diseases. Eighty-eight participants were randomized: 44 for the Control Group and 44 for the Intervention Group. When comparing the demographic and biochemical characteristics, there were no differences between groups except for serum glucose (GC=110.4±46.8mg/dL and GI93.1±16.9mg/dL, p=0.039). Conclusion This study protocol describes the methodology used in the study of educational intervention for the promotion of health care of patients on the waiting list for bariatric surgery. It shows that there is similarity between the baseline comparison groups. Registro Brasileiro de Ensaios Clínicos (Brazilian Clinical Trials Registry), RBR-775y3d.

Associations between change in sedentary behavior and outcome in standard behavioral weight loss treatment

Sedentary behavior, particularly in prolonged periods, is an important determinant of health. Little research exploring changes in sedentary behavior during behavioral weight loss programs exists. This study evaluated the magnitude of changes in total and prolonged sedentary behavior and how these changes related to changes in weight and cardiovascular outcomes during a behavioral weight loss program. Participants (n = 450) in two lifestyle modification programs underwent assessments of sedentary behavior (by accelerometry), weight, waist circumference, blood pressure, and resting heart rate at baseline and after 6 months of treatment. Sedentary behavior was defined as both total and prolonged (≥30 continuous minutes) sedentary minutes/day. Reductions in total and prolonged sedentary time were significant and were accounted for by increases in moderate-to-vigorous physical activity (MVPA). Only changes in MVPA significantly predicted change in weight when entered into a model simultaneously with changes in sedentary behavior. Changes in total and prolonged sedentary time were not associated with changes in waist circumference, heart rate, or blood pressure. Change in sedentary time was not independently associated with change in health outcomes during a behavioral weight loss treatment. High variability in changes in sedentary time indicate that individual differences may be important to examine. Reducing sedentary time may not be powerful enough to impact these health outcomes above the effects of other changes made during these programs; alternatively, it may be that increasing focus in treatment on reducing sedentary time may engender greater decreases in sedentariness, which could lead to better health outcomes.

Design of ChooseWell 365: Randomized controlled trial of an automated, personalized worksite intervention to promote healthy food choices and prevent weight gain

BACKGROUND/AIMS

Behavioral nudges in the food environment increase healthy choices, but it is unknown if they improve diet and health. The ChooseWell 365 study will determine if an automated, personalized worksite intervention to nudge healthier choices improves overall diet and cardiometabolic health.

DESIGN

Randomized controlled trial of 602 hospital employees who regularly use on-site cafeterias and pay with an employee ID.

INTERVENTION

The intervention combines an environmental strategy (traffic-light labeling) with objective feedback and personalized nudges (health/lifestyle tips, social norms, incentives) to promote healthy food choices. The ChooseWell 365 software platform automatically generates personalized emails and letters that integrate employees' weight goals with health, lifestyle, and cafeteria purchasing data. Over one year, the intervention group receives two weekly emails. One provides a log of daily purchases; the second provides personalized health/lifestyle tips. The intervention group receives monthly mailed letters with social norm comparisons and financial incentives for healthier purchases. The one-year intervention will be completed in February 2019; all follow-up will be completed March 2020.

OUTCOMES

Weight, cardiometabolic risk factors, and dietary intake at one and two-year follow-up. Other outcomes include worksite food purchases by study participants and other non-participant employees who are socially connected (inferred from purchasing data) to participants.

CONCLUSIONS

ChooseWell 365 tests a novel strategy to deliver a scalable worksite prevention program that is integrated into the workday. The intervention is personalized but automated and therefore does not require costlier individual counseling. In the future, this program could be applied broadly in other worksite settings.

"Remind-to-Move" for Promoting Upper Extremity Recovery Using Wearable Devices in Subacute Stroke: A Multi-Center Randomized Controlled Study

This paper examined the effects of "Remind-to-Move" (RTM) via vibration cueing using wearable devices to increase the use of the affected upper limb and integrate upper limb activities undertaken at home in patients with subacute stroke after inpatient discharge. In a multi-centered randomized controlled trial, 84 eligible patients from four general hospitals, who had a first stroke in the last six months, were randomly allocated to either an experimental, sham, or control group, stratified by arm function levels. Patients in the experimental group were treated by RTM, using wearable devices for three consecutive hours daily, over four weeks. The sham group used sham devices, and the control group received usual care alone. A masked assessor evaluated the patients at 0th, 4th, 8th, and 12th weeks using outcome measures included arm function tests, motor activity log, and movement recorded by the devices. Results showed that there was a significant group by time interaction, and the average movement amount and Action Research Arm Test score in the experimental group were significantly higher than in the sham group. This paper demonstrates that RTM via wearable devices used for the hemiplegic upper extremities could promote more arm recovery than the sham or control and, hence, produce an optimal functional improvement for subacute stroke patients.

A weight loss intervention delivered by peer coaches in primary care: Rationale and study design of the PROMISE trial

Primary care offers a familiar and accessible clinical venue for patients with obesity to receive evidence-based lifestyle interventions for weight management. However, there are numerous barriers to the implementation of such programs in primary care, and previous primary care weight loss interventions demonstrate modest and temporary effects. Weight loss treatment delivered within primary care by peer coaches may offer a viable and effective alternative. The purpose of this trial is to test the effects of weight loss treatment that includes ongoing support from a peer coach (i.e., trained, salaried community health workers) as compared to self-directed treatment. Peer coach treatment will be delivered over 18 months and includes a combination of in-person, group-based office visits and individual telephone contacts. This weight loss trial will include 375 adults with obesity (BMI = 30-50 kg/m2) randomized from 10 primary care practices. The primary outcome will be changes in body weight at month 18. Secondary outcomes will include key patient-centered outcomes, including quality-of-life, physical and social functioning, mood, and treatment satisfaction. The cost-effectiveness of the peer coach intervention will also be evaluated. If this novel intervention is effective, it could offer a practical and sustainable approach for the delivery of weight loss treatment in primary care that has the potential to improve clinical outcomes for patients, increase treatment options for primary care providers, and reduce obesity-related healthcare utilization and costs.

Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial

IMPORTANCE

Dietary modification remains key to successful weight loss. Yet, no one dietary strategy is consistently superior to others for the general population. Previous research suggests genotype or insulin-glucose dynamics may modify the effects of diets.

OBJECTIVE

To determine the effect of a healthy low-fat (HLF) diet vs a healthy low-carbohydrate (HLC) diet on weight change and if genotype pattern or insulin secretion are related to the dietary effects on weight loss.

DESIGN, SETTING, AND PARTICIPANTS

The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) randomized clinical trial included 609 adults aged 18 to 50 years without diabetes with a body mass index between 28 and 40. The trial enrollment was from January 29, 2013, through April 14, 2015; the date of final follow-up was May 16, 2016. Participants were randomized to the 12-month HLF or HLC diet. The study also tested whether 3 single-nucleotide polymorphism multilocus genotype responsiveness patterns or insulin secretion (INS-30; blood concentration of insulin 30 minutes after a glucose challenge) were associated with weight loss.

INTERVENTIONS

Health educators delivered the behavior modification intervention to HLF (n = 305) and HLC (n = 304) participants via 22 diet-specific small group sessions administered over 12 months. The sessions focused on ways to achieve the lowest fat or carbohydrate intake that could be maintained long-term and emphasized diet quality.

MAIN OUTCOMES AND MEASURES

Primary outcome was 12-month weight change and determination of whether there were significant interactions among diet type and genotype pattern, diet and insulin secretion, and diet and weight loss.

RESULTS

Among 609 participants randomized (mean age, 40 [SD, 7] years; 57% women; mean body mass index, 33 [SD, 3]; 244 [40%] had a low-fat genotype; 180 [30%] had a low-carbohydrate genotype; mean baseline INS-30, 93 μIU/mL), 481 (79%) completed the trial. In the HLF vs HLC diets, respectively, the mean 12-month macronutrient distributions were 48% vs 30% for carbohydrates, 29% vs 45% for fat, and 21% vs 23% for protein. Weight change at 12 months was -5.3 kg for the HLF diet vs -6.0 kg for the HLC diet (mean between-group difference, 0.7 kg [95% CI, -0.2 to 1.6 kg]). There was no significant diet-genotype pattern interaction (P = .20) or diet-insulin secretion (INS-30) interaction (P = .47) with 12-month weight loss. There were 18 adverse events or serious adverse events that were evenly distributed across the 2 diet groups.

CONCLUSIONS AND RELEVANCE

In this 12-month weight loss diet study, there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet, and neither genotype pattern nor baseline insulin secretion was associated with the dietary effects on weight loss. In the context of these 2 common weight loss diet approaches, neither of the 2 hypothesized predisposing factors was helpful in identifying which diet was better for whom.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01826591.

The impact of methods to handle missing data on the estimated prevalence of dementia and mild cognitive impairment in a cross-sectional study including non-responders

OBJECTIVE

Although several statistical methods for adjusting for missing data have been developed and are widely applied in research, few studies have investigated these methods in adjusting for missingness in datasets that aim to estimate the prevalence of dementia. We attempted to develop a more feasible approach for handling missingness in a cross-sectional study among elderly.

METHODS

Five methods of estimating prevalence, including stratified weighting (SW), inverse-probability weighting (IPW), hot deck imputation (HDI), ordinal logistic regression (OLR) and multiple imputation (MI), were applied to handle the missing data yielded by a dataset that include 2231 non-responders.

RESULTS

Compared with the results of the complete case analysis, the differences in the prevalence rates of dementia and mild cognitive impairment (MCI) calculated by the prevalence-estimating methods after adjusting for non-responders were less than 7% and 6%, respectively. In contrast to the results of other methods, the estimated prevalence of dementia and MCI calculated by MI increased when more predictive factors were included, and the lowest rate of missing data was achieved using MI. Using the participants' ages, the cognitive screening sores and activity of daily life sores as predictive variables when correcting for missingness induced relatively larger effects on the estimated dementia prevalence.

CONCLUSIONS

When adjusting for missingness while estimating the prevalence of dementia in cross-sectional studies, a simple method, such as SW, is recommended when limited information is available, whereas MI is the preferred method when additional information is available. Further simulation studies are needed to determine the optimal approach.

Effect of interdisciplinary care on weight loss: a randomised controlled trial

OBJECTIVE

To determine the effectiveness of a novel interdisciplinary treatment compared with usual care on weight loss in overweight and obese adult volunteers.

DESIGN

Single blinded controlled trial. Participants randomly assigned to usual care (C, general guideline-based diet and exercise advice), intervention (I, interdisciplinary protocol) or intervention + a healthy food supplement (30 g walnuts/day) (IW).

SETTING

Community based study, Illawarra region, south of Sydney, Australia.

PARTICIPANTS

Generally well volunteer adult residents, 25-54 years, body mass index (BMI) 25-40kg/m² were eligible. At baseline 439 were assessed, 377 were randomised, 298 completed the 3-month intensive phase and 178 completed the 12-month follow-up.

INTERVENTIONS

Treatment was provided at clinic visits intensively (0 months, 1 month, 2 months, 3 months) then quarterly to 12 months. Support phone calls were quarterly. All participants underwent blinded assessments for diet, exercise and psychological status.

PRIMARY AND SECONDARY MEASURES

The primary outcome was difference in weight loss between baseline and 12 months (clinically relevant target 5% loss). Secondary outcomes were changes in blood pressure, fasting blood glucose and lipids, and changes in diet, exercise and psychological parameters.

RESULTS

At 12 months, differences in weight loss were identified (p<0.001). The I group lost more than controls at 3 months (91.11 (92.23,90.00), p<0.05) and the IW more than controls at 3 months (91.25 (92.35,90.15), p<0.05) and 6 months (92.20 (93.90,90.49), p<0.01). The proportion achieving 5% weight loss was significantly different at 3 months, 6 months and 9 months (p=0.04, p=0.03, p=0.03), due to fewer controls on target at 3 months, 6 months and 9 months and more IW participants at 6 months. Reductions in secondary outcomes (systolic blood pressure, blood glucose/lipid parameters and lifestyle measures) followed the pattern of weight loss.

CONCLUSIONS

An interdisciplinary intervention produced greater and more clinically significant and sustained weight loss compared with usual care. The intensive phase was sufficient to reach clinically relevant targets, but long-term management plans may be required.

TRIAL REGISTRATION NUMBER

ANZCTRN 12614000581662; Post-results.

Long-term effects of a randomized, controlled, tailor-made weight-loss intervention in primary care on the health and lifestyle of overweight and obese women

BACKGROUND

Maintenance of weight loss after a diet and exercise intervention is often low. Moreover, short follow-up periods and high attrition rates often impede translation of study results to clinical practice.

OBJECTIVE

The present study evaluated the long-term effectiveness of a randomized, tailor-made lifestyle intervention, consisting of diet and exercise, on the health and lifestyle of overweight, middle-aged women in primary care.

DESIGN

The intervention was part of a randomized controlled trial on the prevention of knee osteoarthritis [PROOF (PRevention of knee Osteoarthritis in Overweight Females) study]. The intervention lasted 2.5 y and consisted of visits to the dietitian and participation in physical activity classes, supervised by a physiotherapist. The outcome of main interest of the present study was weight change (in kg) 6-7 y after randomization. Additionally, the intervention's effect on change in physical activity was investigated.

RESULTS

After 6 mo, weight loss was significantly higher in the intervention group (adjusted difference: 1.34 kg; 95% CI: 0.46, 2.22 kg). Over time, this difference decreased and became nonsignificant after 24 mo. Per-protocol analyses showed similar results. After 6 mo, change in physical activity was significantly higher in the intervention group (15.2%; 95% CI: 28.6%, 1.7%). Over time, this difference increased up to 29.8% (95% CI: 2.3%, 57.2%) after 6.6 y of follow-up. Per-protocol analyses showed no significant differences in change in physical activity.

CONCLUSIONS

A long-lasting intervention effect on change in physical activity was found, which increased over time. For weight change, smaller differences were found, which decreased over time. In future research, greater intervention effects on weight change are expected when higher compliance rates can be reached. The present study provides important recommendations for future research. The PROOF study was registered at http://www.isrctn.com as ISRCTN42823086.

From last supper to self-initiated weight loss: Pretreatment weight change may be more important than previously thought

OBJECTIVE

Evaluate the association between pretreatment and during-treatment weight change, as well as differences in self-regulation between those who gain weight, remain weight stable, and lose weight pretreatment.

METHODS

Data from the first 6 months of a behavioral weight loss study were used. Participants (n = 283) were weighed at two assessment points (screening visit and baseline) prior to the start of treatment and at every treatment session. Participants were divided into those who gained weight, remained weight stable, or lost weight between the screening visit and the first treatment session.

RESULTS

Pretreatment weight change was not significantly associated with during-treatment change. Weight change from the screening visit to month 6 was significantly different by category, with losses of 11% and 7% for those who lost and gained weight pretreatment, respectively. Weight change from first treatment session to month 6 was not different by category. Poorer self-regulation was associated with pretreatment weight gain and better self-regulation with pretreatment weight loss.

CONCLUSIONS

Pretreatment weight change may not relate to success during behavioral weight loss treatment. Researchers should carefully consider when the "baseline" assessment takes place to reduce bias introduced by pretreatment weight change. Poorer self-regulation may place individuals at risk for weight gain prior to treatment.

Evaluation of an 18-month commercial multidisciplinary obesity treatment programme

The treatment of obesity is an often studied subject. Although reductions in weight and improvements in cardiometabolic risk factors are important aims of obesity treatment, improvements in quality of life and eating behaviour are also relevant outcomes. In this practice-based study, we evaluated an 18-month commercial multidisciplinary obesity treatment programme and report on treatment results for weight, cardiometabolic risk factors, eating behaviour and quality of life. From a local commercial obesity treatment centre, 426 subjects (65% female; 45.4 ± 12.2 years; body mass index 40.0 ± 6.6 kg m(-2)) were recruited. Measurements of body weight, height, body composition, waist circumference and blood pressure were scheduled at baseline and every 3 months, whereas fasting blood collections were scheduled at baseline and every 6 months. At the same time points, participants were asked to fill in questionnaires on dietary intake, eating behaviour and quality of life. After 18 months of treatment programme, average weight change [mean (95% confidence interval)] was -10.9 kg (-14.8 to -7.0; P < 0.001) for the completers (n = 181) and -10.8 kg (-14.2 to -7.4; P < 0.001) for the intention-to-treat population (n = 426). Waist circumference (mean ± standard error of the mean) (-0.13 ± 0.01 cm; P < 0.001), fat mass (-7.8 ± 1.3 kg; P < 0.001) systolic (-11.4 ± 2.0; P < 0.001) and diastolic (-7.0 ± 1.3; P < 0.001) blood pressure, triglycerides (-0.4 ± 0.1; P = 0.004) and plasma glucose (-0.6 ± 0.2; P = 0.001) were significantly reduced. The PCS scale of the SF-36 and all three scales of the three-factor eating questionnaire improved significantly over the 18-month treatment period. All collected data in this study provide evidence that a multidisciplinary treatment programme based on lifestyle modification results in significant weight loss and improvements in cardiometabolic risk factors, quality of life and eating behaviour.

The joint influence of gender and amount of smoking on weight gain one year after smoking cessation

Weight gain is often associated with smoking cessation and may discourage smokers from quitting. This study estimated the weight gained one year after smoking cessation and examined the risk factors associated with weight gain in order to identify socio-demographic groups at higher risk of increased weight after quitting. We analyzed data from 750 adults in two randomized controlled studies that included smokers motivated to quit and found a gradient in weight gain according to the actual duration of abstinence during follow-up. Subjects who were abstinent for at least 40 weeks gained 4.6 kg (SD = 3.8) on average, compared to 1.2 kg (SD = 2.6) for those who were abstinent less than 20 weeks during the 1-year follow-up. Considering the duration of abstinence as an exposure variable, we found an age effect and a significant interaction between sex and the amount of smoking before quitting: younger subjects gained more weight than older subjects; among light smokers, men gained more weight on average than women one year after quitting, while the opposite was observed among heavy smokers. Young women smoking heavily at baseline had the highest risk of weight gain after quitting.

Reporting of missing data and methods used to accommodate them in recent analgesic clinical trials: ACTTION systematic review and recommendations

Missing data in clinical trials can bias estimates of treatment effects. Statisticians and government agencies recommend making every effort to minimize missing data. Although statistical methods are available to accommodate missing data, their validity depends on often untestable assumptions about why the data are missing. The objective of this study was to assess the frequency with which randomized clinical trials published in 3 major pain journals (ie, European Journal of Pain, Journal of Pain, and Pain) reported strategies to prevent missing data, the number of participants who completed the study (ie, completers), and statistical methods to accommodate missing data. A total of 161 randomized clinical trials investigating treatments for pain, published between 2006 and 2012, were included. Approximately two-thirds of the trials reported at least 1 method that could potentially minimize missing data, the most common being allowance of concomitant medications. Only 61% of the articles explicitly reported the number of patients who were randomized and completed the trial. Although only 14 articles reported that all randomized participants completed the study, fewer than 50% of the articles reported a statistical method to accommodate missing data. Last observation carried forward imputation was used most commonly (42%). Thirteen articles reported more than 1 method to accommodate missing data; however, the majority of methods, including last observation carried forward, were not methods currently recommended by statisticians. Authors, reviewers, and editors should prioritize proper reporting of missing data and appropriate use of methods to accommodate them so as to improve the deficiencies identified in this systematic review.