Credibility at stake: only two-thirds of randomized trials of nutrition interventions are registered and lack transparency in outcome and treatment effect definitions.

OBJECTIVES: This study aimed to investigate the adherence of randomized controlled trials of nutrition interventions to transparency practices informing assessments of selective reporting biases, including the availability of a trial registration entry, protocol and statistical analysis plan (SAP). STUDY DESIGN AND SETTING: Retrospective observational study with cross-sectional design. We systematically searched for trials published from 1 July 2019, to 30 June 2020, and included a randomly selected sample of 400 studies. We searched for registry entries, protocols, and SAPs for all included studies. We extracted data to characterize the disclosure of sufficient information in the available materials to inform assessments of selective reporting biases, considering the definition of outcome domain, measure, metric, method of aggregation, time point, analysis population, methods to handle missing data and method of adjustment. RESULTS: Most trials (69%) were registered, but these often lacked sufficient specification of outcomes and intended treatment effects. Protocols and SAPs provided more details but were less often available (14% and 3%, respectively), and even then, almost all studies presented limited information to inform the assessments of risk of bias due to the selection of the reported result. CONCLUSION: Lack of full specification of outcomes and intended treatment effects hinder a full adherence of randomized controlled trials of nutrition interventions to transparency practices and may affect their credibility.

Effect of oral nutritional supplements with or without nutritional counselling on mortality, treatment tolerance and quality of life in head-and-neck cancer patients receiving (chemo)radiotherapy: a systematic review and meta-analysis.

Oral nutritional supplements are widely recommended to head-and-neck cancer patients undergoing anti-cancer treatment; however, their effects on the outcomes of most importance to patients are unclear. This study aimed to systematically review the evidence of effect of oral nutritional supplements on mortality, treatment tolerance, quality of life, functional status, body weight and adverse effects. We searched PubMed, Embase, CENTRAL, LILACS, Web of Science, CINAHL, two trial registry platforms, three sources of grey literature and reference lists of included studies. We assessed the risk of bias using the revised Cochrane risk-of-bias tool (RoB 2), and certainty of evidence using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. We used random-effects models with Hartung-Knapp correction for the meta-analyses. We included fifteen trials, of which five were ongoing or unpublished, providing evidence in four comparisons. We found very low to low certainty evidence for the effect of oral nutritional supplements on mortality, treatment tolerance, quality of life, functional status and adverse effects. When compared with nutritional counselling alone, nutritional counselling plus oral nutritional supplements probably increased body weight slightly. We also found adverse events relating to supplements use such as nausea, vomiting and feeling of fullness. Possible increases in mortality, treatment tolerance and quality of life besides a possible decrease in functional status are worthy of further investigation. Future research could attempt to address the clinical importance of a probable increase in body weight. Possible adverse effects of the use of oral nutritional supplements should not be overlooked.