Table 2 Study inclusion and exclusion criteria using modified PICO [27, 28]

Patient/Population:

Peer reviewed journal articles and conference papers published anytime up to end of February 2018.

Patients or health care professionals (clinicians) stakeholder views participating in RCTs with a surgical and non-surgical comparison.

Articles in English language published in any country.

Unpublished dissertations, book chapters, papers or conference abstracts without corresponding full text articles.

Studies with participants under 18 years of age.

Intervention:

RCTs with a surgical and non-surgical comparison

Comparison:

Randomised controlled trials that have a surgical and non-surgical comparison, e.g. physiotherapy, drugs, medical management.

Outcomes:

Challenges related to the design and conduct of RCTs with a surgical and non-surgical comparison such as recruitment, retention, compliance with treatment allocation.

Studies:

Qualitative studies (or mixed methods studies containing substantial qualitative components that can make a contribution to the meta-synthesis). As an operational definition data collected were in the form of semi-structured interviews, focus groups, open ended evaluation forms including free text responses, observational field notes, or reflective journals. Papers should report some form of thematic or inductive analysis.

Studies of recruitment into surgical studies that are not randomised controlled trials.

No qualitative analysis undertaken, or primarily quantitative data reported. This includes questionnaire data.