Table 2.

SPIDER tool

SPIDER elements	Keywords	Search terms and synonyms
S (Sample)	Health professionals	Health professional* or doctor* or clinician* or consultant* or GP or general practitioner* or physician* or pharmacist*
PI (Phenomenon of Interest)	Clinical practice guidelines for rare diseases	Guideline* or guidance or prescrib* or clinical protocol* or prescription* rare dis* or rare diagnos* or orphan dis*
D (Design)	Qualitative or mixed methodology	Ovid Medline qualitative search filter(23): (((“semi-structured” or semistructured or unstructured or informal or “in-depth” or indepth or “face-to-face” or structured or guide) adj3 (interview* or discussion* or questionnaire*)) or (focus group* or qualitative or ethnograph* or fieldwork or “field work” or “key informant”)).ti,ab. Or Interviews as topic/ or focus groups/ or narration/ or qualitative research/
E (Evaluation)	Influencing factors	Barrier* or facilit* or help* or hinder* or compliance or comply or complies or accept* or conform* or approv* or adhere* or strateg*
R (Research type)	Qualitative	Qualitative research/