Assessing the completeness and comparability of outcomes in systematic reviews addressing food security: protocol for a methodological study

BACKGROUND: Systematic reviews should specify all outcomes at the protocol stage. Pre-specification helps prevent outcome choice from being influenced by knowledge of included study results. Completely specified outcomes comprise five elements: (1) domain (title), (2) specific measurement (technique/instrument), (3) specific metric (data format for analysis), (4) method of aggregation (how group data are summarised), and (5) time points. This study aims to assess the completeness of outcome pre-specification in systematic reviews of interventions to improve food security, specifically food availability, in low- and middle-income countries, as well as to assess the comparability of outcome elements across reviews reporting the same outcome domains. METHODS: We will examine systematic reviews from an ongoing overview of systematic reviews, which assessed the effects of interventions addressing food insecurity through improving food production, access, or utilisation compared with no intervention or a different intervention, on nutrition outcomes. We will examine the original protocols; if unavailable, we will examine the “Methods” section of the systematic reviews’ most recent version. One investigator will identify and group all outcome domains that the authors of the included protocols intended to measure in the systematic review and a second investigator will verify the domains. For outcome domains reported in at least 25% of protocols, one author will extract data using a pre-specified form and a second author will verify the data. We will use descriptive statistics to report the number, types, and degree of specification of outcomes in included protocols. We will assess the extent of completeness of outcome pre-specification based on the number of outcome elements (out of five). We will assess comparability of outcome domains through examining how individual elements are described across SRs reporting the same outcome domains. DISCUSSION: Our findings will contribute to understanding about the best approach to pre-specify outcomes for systematic reviews and primary research in the field of food security.