Table 1 Review inclusion and exclusion criteria

Inclusion criteria

    P – population

Frail patients who had to undergo surgery; prehabilitation patients had to include frail individuals; term frail/frailty had to be used in the article, or a structured/standardised frailty assessment had to be conducted, e.g., concept of frailty by Fried et al. [27]

    I – intervention

Prehabilitation programme

    C – comparator

Experimental studies could include a comparison group, but this was not a condition of inclusion. Observational studies and other article types did not have to include a comparison group.

    O – outcomes

Facilitators and barriers to the implementation of prehabilitation for frail patients into routine health care. These can be considered from different perspectives such as the patients, the surgeons, the institutions, or the therapists carrying out the prehabilitation programme.

    S – study design

No restriction on study design, includes non-empirical sources, or publication type, i.e., grey literature like dissertations, opinion papers etc.

    H – healthcare context

Any healthcare setting that provides prehabilitation to frail patients, including ambulatory, inpatient, or partially inpatient, or community settings. Home-based interventions, including tele-medical interventions, were also included.

Exclusion criteria

    - Publication language other than English or German

    - Study registration records and other documentation (e.g., conference abstracts) of ongoing studies on the (cost-)effectiveness and/or safety of prehabilitation

    - Programmes that were comprised of medication or supplement intake only as well as mere educational programmes

    - Prehabilitation programmes prior to chemotherapy or other non-surgical interventions

    - Articles were excluded if they did not contain information that hints at challenges, problems, supportive or helpful factors for the implementation of prehabilitation programmes for frail patients