The usefulness of randomized trials of lifestyle interventions for overweight, obesity, or metabolic syndrome: A systematic review.

BACKGROUND: Randomized controlled trials (RCTs) widely considered the gold standard for evidence-based healthcare may be limited in their clinical usefulness in lifestyle interventions for adults with overweight, obesity, or metabolic syndrome. OBJECTIVE: In this systematic review of lifestyle intervention RCTs we delineated trial usefulness. METHODS: Following prospective registration in PROSPERO (CRD4202347896), we conducted a comprehensive search across Medline, Scopus, Web of Science, and the Cochrane Library databases, covering the period from inception to December 2023. RCTs involving dietary interventions, with or without physical activity, and with or without behavioural support were included. Two reviewers independently performed study selection and data extraction. Study usefulness was assessed using a multidimensional 14 item questionnaire. Percentage compliance with usefulness items was computed. RESULTS: Of 1175 records, 30 RCTs (12,841 participants) were included. Among these, 13 (43%) RCTs complied with half of the usefulness items and only 3 (10%) complied with two-thirds of the items. For each usefulness item individually: 30 (100%) reported the burden of the problem addressed, 15 (50%) contextualized the trial through a systematic review, 18 (60%) presented an informative trial with clinically meaningful outcomes evaluated at a stated statistical power, 17 (57%) had low risk of bias, 2 (7%) exhibited pragmatic features pertaining to the trial methodologies and outcomes relevant to real-world application.18 (60%) were patient centred with formal patient involvement, none (0%) demonstrated value for money, 17 (57%) were completed according to their feasibility assessment achieving at least 90% of the estimated sample size, and 30 (100%) reported at least one of five transparency or openness features. CONCLUSION: Only one in 10 lifestyle RCTs met two-thirds of the usefulness features. It is imperative to meet these criteria when devising future trials within the field of nutrition to reduce research waste.

Two-Year Changes in Physical Activity and Concurrent Changes in Cognitive Function in a Cohort of Adults with Metabolic Syndrome.

BACKGROUND: It has been proposed that physical activity (PA) could prevent cognitive decline. OBJECTIVE: To evaluate the association between changes in PA and changes in cognitive function in a cohort of adults with metabolic syndrome. METHODS: Longitudinal observational study including 5,500 adults (mean age 65 years, SD = 5; women = 49.3% ) with metabolic syndrome. Participants underwent physical activity measurements and cognitive evaluation at baseline and at two-years of follow-up. PA was quantified using the Minnesota questionnaire-shortened version. Cognitive function was evaluated using a battery of tests: Mini-Mental Test Examination, Clock Drawing Test, Trail Making Test A and B, Verbal Fluency Test, and Digit Span. The primary outcome was two-year change in cognition, measured through the Global Composite Score (GCS) of all neuropsychological tests. Multivariable-adjusted linear regression models were fitted with baseline PA and their changes as the main exposures and changes in cognitive function as the outcome. RESULTS: No significant association was found between PA levels (or their changes) in the GCS of cognitive function. A greater increase in PA levels was associated with a more favorable two-year change in the Trail Making Test A (Q4 versus Q1: b = - 2.24s, 95% CI -4.36 to -0.12s; p-trend = 0.020). No significant association was found for other neuropsychological test. CONCLUSION: Our results do not support an association between increases in PA and the evolution of the global cognitive function at two-year in an intervention trial which included PA promotion in one of its two randomized arms, but they suggested a possible beneficial effect of PA on attentional function in older adults.

Benefits of Participation in Clinical Trials: An Umbrella Review.

Participation in randomised clinical trials (RCTs) entails taking part in the discovery of effects of health care interventions. The question of whether participants' outcomes are different to those of non-participants remains controversial. This umbrella review was aimed at assessing whether there are health benefits of participation in RCTs, compared to non-participation. After prospective registration (PROSPERO CRD42021287812), we searched the Medline, Scopus, Web of Science and Cochrane Library databases from inception to June 2022 to identify relevant systematic reviews with or without meta-analyses. Data extraction and study quality assessment (AMSTAR-2) were performed by two independent reviewers. Of 914 records, six systematic reviews summarising 380 comparisons of RCT participants with non-participants met the inclusion criteria. In two reviews, the majority of comparisons were in favour of participation in RCTs. Of the total of comparisons, 69 (18.7%) were in favour of participation, reporting statistically significant better outcomes for patients treated within RCTs, 264 (71.7%) comparisons were not statistically significant, and 35 (9.5%) comparisons were in favour of non-participation. None of the reviews found a harmful effect of participation in RCTs. Our findings suggest that taking part in RCTs may be beneficial compared to non-participation.

A systematic review and meta-analysis of weight loss in control group participants of lifestyle randomized trials.

Randomized clinical trials (RCTs) of lifestyle modification have reported beneficial effects of interventions, compared to control. Whether participation in the control group has benefits is unknown. To determine whether control group participants experience weight loss during the course of RCTs. After prospective registration (PROSPERO CRD42021233070), we conducted searches in Medline, Scopus, Web of Science, Cochrane library and Clinicaltrials.gov databases from inception to May 2021 without language restriction to capture RCTs on dietary advice or physical activity interventions in adults with overweight, obesity or metabolic syndrome. Data extraction and study quality assessment was performed by two independent reviewers. Weight loss in the control group, i.e., the difference between baseline and post-intervention, was pooled using random effects model generating mean difference and 95% confidence interval (CI). Heterogeneity was assessed using the I2 statistical test. Subgroup meta-analysis was performed stratifying by follow-up period, type of control group protocols and high-quality studies. Among the 22 included studies (4032 participants), the risk of bias was low in 9 (40%) studies. Overall, the controls groups experienced weight loss of - 0.41 kg (95% CI - 0.53 to - 0.28; I2 = 73.5% p < 0.001). To identify a result that is an outlier, we inspected the forest plot for spread of the point estimates and the confidence intervals. The magnitude of the benefit was related to the duration of follow-up (- 0.51 kg, 95% CI - 0.68, - 0.3, for 1-4 months follow-up; - 0.32 kg, 95% CI - 0.58, - 0.07, 5-12 months; - 0.20 kg, 95% CI - 0.49, 0.10, ≥ 12 months). In high-quality studies we found an overall weight loss mean difference of - 0.16 (95% CI - 0.39, 0.09) with a considerable heterogeneity (I2 = 74%; p < 0.000). Among studies including control group in waiting lists and combining standard care, advice and material, no heterogeneity was found (I2 = 0%, p = 0.589) and (I2 = 0%, p = 0.438); and the mean difference was - 0.84 kg (95% CI - 2.47, 0.80) and - 0.65 kg (95% CI - 1.03, - 0.27) respectively. Participation in control groups of RCTs of lifestyle interventions had a benefit in terms of weight loss in meta-analysis with heterogeneity. These results should be used to interpret the benefits observed with respect to intervention effect in trials. That control groups accrue benefits should be included in patient information sheets to encourage participation in future trials among patients with overweight and obesity.