Table 4 Facilitators and barriers mentioned by authors

 Matwiejczyk et al. [42]

“Heterogeneity of the reviews and the assessment of insufficient information in three reviews precluded an evaluation of the quality of the research through the use of GRADE. This was compounded by the difficulty for the systematic reviews to apply GRADE or a meta-analysis for the same reason.”

 Dyson et al. [30]

“It is acknowledged that much of the evidence from nutrition research is derived from prospective cohort studies rather than RCTs, and applying GRADE downgrades evidence from prospective studies when compared with RCTs; this should be borne in mind when considering the grading allocated to each recommendation.”

“A key aspect of current approaches to supporting people with diabetes is to encourage practice that is individualized. It is challenging to rate such recommendations using the GRADE system, particularly in situations where multiple conditions influence health and dietary approaches. In response to this, a deliberate decision was made to report these recommendations as ‘Not Rated’”

 Erickson et al. [32]

We planned to use GRADE to evaluate the quality of the evidence used in the model components as well as the accuracy of the modeling procedure; however, these details were not publicly available, and we were unable to assess the quality of the evidence for the recommendations.

 Baker et al. [24]

“Given that very few studies had reliable measures of physical activity and sedentary behavior, and much of the data were incomplete, a modified approach was required in which we split the presentation of findings according to the risk of bias. […] As conducting meta-analyses was deemed inappropriate, a summary table has been prepared using narrative analysis of the included studies.”

 NICE [45]

It may not be possible, practical or ethical to undertake a randomized controlled trial for some interventions and natural experiments may be the most valid approach. So a modified version of GRADE was agreed by the committee and used. Outcomes from studies for which the natural experiment study design was the most feasible and valid approach started the GRADE process as “high quality.” If a randomized controlled trial was feasible and optimal for answering the study aims but a natural experiment design was used, outcomes started the GRADE process as “low quality.”

 Okely et al. [47]

The GRADE-ADOLOPMENT approach allows guideline developers to follow a well-accepted and transparent process for developing guidelines (GRADE) in an efficient manner by adapting or adopting an existing evidence-based guideline. This could potentially prevent the need to undertake (or repeat) costly tasks such as conducting full systematic reviews [13]. At the same time, it allows local guideline developers to take into consideration factors that are specific to their local context.