Risk of Bias in Randomized Controlled Trials of Nutrition Interventions for Frailty in Older Adults

We assessed the risk of bias in randomized controlled trials (RCTs) of nutrition-only interventions and holistic frailty outcomes in older adults. We also explored associations between study-level factors and risk of bias. We searched Cochrane, PubMed, and Scopus for published trials between 01/01/2000 and 11/13/2024. Two persons independently screened each citation at the title and abstract, and full text, levels. They also independently conducted data extraction and assessed risk of bias using the Cochrane Risk of Bias 2 tool. We used responses on the tool to develop index scores between 0-1 for each included article, with higher scores indicating lower risk of bias. We regressed the index scores on four study-level factors, i.e., region of publication, year of publication, journal impact factor, and reported use of CONSORT guidelines. Fifteen articles were included in the study: three had low risk of bias, two had some concerns with bias, and ten had high risk of bias. Domain 2 on the Cochrane tool generated the most challenges with bias, largely due to poor reporting of intention-to-treat analysis and lack of information on how this issue might affect trial results. Median index scores were 0.52, 0.53, and 0.86 for articles with high, some concerns, and low risk of bias, respectively (p = 0.0479). However, the index scores were not associated with any study-level factors. Researchers in the field should note potential biases in the design and conduct of RCTs, especially in data analysis and – more specifically – intent-to-treat analysis.