A summary of study characteristics is available in Tables 1 and 2, with an additional summary of study characteristics displayed in Additional file 1. Specifically, Table 1 provides data on pedagogical methods and evaluation outcomes and Table 2 provides data on intervention delivery, in contrast to the Additional file 1 which organizes the results by study characteristics.

Table 1 summarizes study characteristics for the 32 included studies. Starting from the largest proportion of studies, 16% (5/32) of the studies were published in 2018 [26, 28, 29, 35, 44], and 13% (4/32) of the studies were published in 2015 [36, 43, 45, 46], 2022 [48, 50, 52, 53], and 2023 [47, 49, 51, 54], each. Years 2014 [32, 37, 39] and 2020 [25, 34, 41] made up 9% (3/32) of the studies, each, and 2011 [33, 38], 2016 [30, 31] and 2017 [23, 42] made up 6% (2/32) of the studies, each. Finally, 2012 [27], 2013 [40], and 2021 [24] made up 3% (1/32) of the studies, each.

The majority of the studies were conducted in the United States of America (44%, 14/32) [23,24,25,26,27, 30, 36, 38, 40, 44, 47, 49, 53, 54], followed by the UK (13%, 14/32) [31, 32, 37, 48], Australia (9%, 3/32) [29, 33, 39], Canada (9%, 3/32) [28, 43, 51], Ireland (9%, 3/32) [34, 45, 50], Turkey (6%, 2/32) [42, 52], Belgium (3%, 1/32) [35], Saudi Arabia (3%, 1/32) [41], and South Africa (3%, 1/32) [46].

With regards to trainee demographics, most of the studies were specifically targeted towards medical students (50%, 16/32) [26, 28, 30,31,32, 37, 38, 40, 42,43,44, 46, 47, 51,52,53]. Following medical students, were nursing (25%, 8/32) [23, 24, 33, 43, 44, 48, 50, 54], dentistry (19%, 6/32) [35, 36, 41, 45, 49, 50], psychology (19%, 6/32) [23, 24, 27, 43, 44, 54], physiotherapy (16%, 5/32) [24, 26, 33, 39, 43], occupational therapy (16%, 5/32) [24, 27, 29, 33, 43], social work (16%, 5/32) [23, 24, 33, 34, 54], and speech language pathology (13%, 4/32) [23,24,25, 29] students. Other specialities included in IDD interventions were, audiology (6%, 2/32) [23, 24], nutrition (3%, 1/32) [23], physician assistant (3%, 1/32) [44], dental hygiene (3%, 1/32) [50], and genetic counselling (3%, 1/32) [24].

As for trainees’ year in their respective programs, the results were varied with the most studies including 3rd years (31%, 10/32) [26, 30, 31, 34, 38, 40, 45, 47, 48, 50], followed by 2nd years (28%, 9/32) [26, 27, 33, 46,47,48,49,50, 53], 4th years (22%, 7/32) [32, 35,36,37, 46, 47, 49], and 1st years (16%, 5/32) [27, 28, 33, 51, 53]. However, almost half of the studies were unclear with regards to learner level (19%, 6/32) [23,24,25, 29, 52, 54] or included trainees of all years (16%, 5/32) [39, 41,42,43,44].

Many of the interventions included faculty members (72%, 23/32) [23,24,25,26,27, 29, 32, 34, 36,37,38, 40, 43,44,45,46, 48,49,50,51,52,53,54] and/or patients, parents, or caregivers (53%, 17/32) [23, 28, 30,31,32,33,34, 37, 43, 45, 48,49,50,51,52,53,54] as instructors. Moreover, some studies utilized the expertise of non-faculty professionals as instructors (25%, 8/32) [30,31,32, 40, 48, 50, 51, 54]. Interestingly, a few studies capitalized on the past experiences of previous trainees and/or senior students using them as instructors (6%, 2/32) [28, 33]. Although, for 16% (5/32) of the studies, the instructor type was categorized as unclear [35, 39, 41, 42, 47].

The majority of interventions were single sessions (38%, 12/32) [26, 29,30,31,32,33, 40,41,42,43,44, 50]. On the other hand, there were several studies that were longitudinal of longer than 3 months (16%, 5/32) [23, 24, 34, 46, 54], however some of these studies were non-continuous, and often had varying amounts of time between sessions. Additionally, a significant number of studies were 1–3 months in length (28%, 9/32) [27, 35, 36, 39, 45, 47, 48, 51, 53], and the minority of studies were short-term of less than 1 month (16%, 5/32) [25, 28, 38, 49, 52].

As for the setting of intervention, the majority included non-clinical settings (75%, 24/32) [23,24,25, 28,29,30,31,32,33,34, 36, 37, 41,42,43,44,45, 47,48,49,50,51,52, 54], followed by specialized clinical settings (22%, 7/32) [26, 35, 38, 40, 45, 49, 52], and non-specialized clinical settings (16%, 5/32) [25, 39, 45, 47, 53]. As well, some of the settings were classified as clinical but lacked clarity on whether the setting was a specialized centre or not (6%, 2/32) [24, 27]. Finally, for 3% (1/32) of the studies, the setting of intervention was unclear [46].

Most of the studies used experiential approaches to teaching (88%, 28/32). Experiential activities typically included a clinical experience (63%, 20/32) [24,25,26,27, 29, 31,32,33,34,35,36, 38,39,40, 42, 44, 47, 49, 52, 53], which were defined as any intervention that recreated or involved a clinical encounter, some examples include simulations with standardized patients or role playing (6%, 2/14) [29, 31]. Other forms of experiential teaching took the form of narrative patient/parents/caregiver experiences (31%, 10/32) [23, 28, 30, 37, 43, 46, 48, 51,52,53] and workshops (3%, 1/32) [45]. As well, many of the studies utilized a theoretical approach to teaching (59%, 19/32) [23, 24, 30, 32, 34, 37, 41,42,43,44,45,46,47, 49,50,51,52,53,54], often in the form of didactic lectures. However, some studies utilized case studies, educational DVDs, and interactive virtual scenarios to teach theory. In addition, while still didactic, some studies utilized patients/parents/caregivers as instructors and curriculum developers. Finally, a large proportion of studies utilized interprofessional education (35%, 11/32) [23,24,25,26,27, 29, 33, 43, 44, 50, 54]. Interprofessional methods were always found in addition to other approaches to learning such as experiential and/or theoretical.

A variety of evaluation methods were used to assess intervention outcomes. Participant evaluations of their own learning were overwhelmingly used (84%, 27/32) [23,24,25,26, 28, 30,31,32,33,34, 36, 37, 39,40,41, 43,44,45,46,47,48,49,50,51,52,53,54]. Often, participant evaluations took the form of pre and post intervention surveys, whereby participants were compared to their pre-intervention scores. Evaluations were also done in the form of learning assessments, where acquired knowledge was tested (28%, 9/32) [25, 28, 38, 41, 42, 42, 43, 47, 49]. Some studies chose to evaluate the intervention itself through participant surveys rating intervention design and effectiveness (22%, 7/32) [25, 27,28,29,30, 33, 34]. One of the studies had no evaluation method for learners, as it was a community service-learning experience that focused on community outcomes [35].

As for study outcomes, the Kirkpatrick model was applied to evaluate the outcomes of the educational interventions. Our review produced a mean and median of 2.16 and 2.5, respectively (if 2A = 2.0 and 2B = 2.5). In order of scoring, 9% (3/32) [33, 33, 45] of the studies were graded level 0 due to lack of change demonstrated, 6% (2/32) [27, 34] were graded level 1 indicating only a reaction to the learning experience, 31% (10/32) [26, 29, 38, 44, 48, 50,51,52,53,54] were graded level 2A indicating a change in attitude, 31% (10/32) [24, 28, 31, 40,41,42,43, 46, 47, 49] were graded level 2B indicating a modification of knowledge or skills, 19% (6/32) [23, 25, 30, 32, 36, 39] were graded level 3 indicating a change in behaviour, and 3% (1/32) [37] of the studies were graded level 4A indicating a change in the system/organization practice. No papers were graded level 4B as no significant improvements in student performance as a direct result of the education were seen.

Our BEME evidence-based scoring system review produced a mean and median of 3 and 3, respectively. We graded 16% (5/32) [27, 35, 37, 38, 45] of papers as a grade 1 – no clear conclusions can be deduced, 13% (4/32) [29, 33, 41, 48] of papers as a grade 2 – ambiguous results, although appearance of a trend, 28% (9/32) [24, 26, 28, 34, 44, 46, 49, 50, 54] of papers as a grade 3 – conclusions can probably be based on the findings, and 44% (14/32) [23, 25, 30,31,32, 36, 39, 40, 42, 43, 47, 51,52,53] papers as grade 4 – results are clear and very likely to be true. No papers were graded as 5 – results are unequivocal due to generally small samples and large reliance on questionnaires with no longitudinal evaluations.