Our search yielded 17,107 citations, with two additional citations found by citation tracking. Of those, 4437 duplicates were removed, leaving 12,672 citations screened for title and abstract (Phase I) and 258 full text reviews (Phase II). Nineteen studies reported in 21 articles were critically appraised and included in the qualitative analysis [26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46] (Fig. 1).

We included 13 secondary analyses of Randomized Controlled Trials (RCT) [29, 30, 33,34,35,36,37,38,39, 42, 43, 45, 46], six reports of cohort studies [26,27,28, 32, 41, 44], one non-randomized controlled study [40] and one retrospective study outcome-based analysis [31]. 4,689 participants were included, with drop-out rates reported across studies ranging from 0% to 25.4%. The participants' ages ranged between 18 and 81 years old; two reports did not specify the age of the participants [31, 34]. All included articles were published in English between 2000 and 2021. Studies originated from USA (n = 13) [26,27,28,29,30, 36,37,38,39,40,41,42, 46], Canada (n = 2) [31, 43], Australia (n = 1) [35], Denmark (n = 1) [45], Italy (n = 1) [34], Netherlands (n = 1) [44], UK (n = 1) [33], and Switzerland (n = 1) [32]. Eight studies had a follow-up time of less than one month [26, 27, 29, 41, 43, 45], seven between one and three months [28, 30, 32, 33, 35, 42, 44, 46], three had a follow-up between six months and one year [31, 34, 36], and three studies followed participants to discharge [37,38,39]. In two studies [37, 39], patients were discharged once the clinician felt the patient had met their maximal improvement within the current treatment program. There were no restrictions on total visits for each patient enrolled in this trial. Discharge was not specified in one other study [38].

Twenty of the 21 reports related to phase 1 explanatory information [26,27,28,29,30,31,32,33,34,35,36,37,38,39,40, 42,43,44,45,46], and one report related to phase 3 understanding and testing of the prognostic pathway [41].

Most included studies (n = 18) focused on clinical change measuring disability using self-reported questionnaires, while less than 25% (n = 5) focused on the overall perception of perceived change. For Patient Reported Outcomes Measures (PROMS), 12 studies reported results on pain intensity using a VAS (n = 5) [29,30,31, 35,