Table 1.
Characteristics of studies included in the systematic review and meta-analysis
| Source | Country | Design | Sample | Response rate | Outcome | Qualitya |
|---|---|---|---|---|---|---|
| Maisiak et al. 1980 [31] | US | Non-controlled trial | 145 | 88% | Effectiveness of an educational intervention | 2 |
| Dornbush et al. 1985 [16] | US | Cross-sectional | 144 | 72% | Change in MS-ATU | 4 |
| Ewan et al. 1987 [32] | AU | Cross-sectional | 156 | 71.2% | Change in MS-ATU | 4 |
| Ewan et al. 1988 [33] | AU | Cohort | 63 | 68% | Change in MS-ATU | 2 |
| Dornbush et al. 1991 [34] | US | Cross-sectional | 71 | 38% | Change in MS-ATU | 4 |
| Crandall et al. 1993 [12] | US | Cross-sectional | 220 | 80.9% | Change in MS-ATU | 4 |
| Tippets & Westphelling, 1993 [35] | US | Cross-sectional | 560 | NA | Mediating factors | 4 |
| Campos-Outcalt et al. 1997 [36] | US | Case-control | 193 | 68.4% | Effectiveness of an educational intervention | 3 |
| Crandall et al. 1997 [13] | US | Cohort | 495 | 80% | Change in MS-ATU | 2 |
| O’Toole et al. 1999 [37] | US | Cohort | 160 | 68.5% | Effectiveness of an educational intervention | 2 |
| Weitzmann et al. 2000 [38] | US | Cross-sectional | 141 | 71% | Change in MS-IWU | 4 |
| Markham et al. 2001 [39] | US | Non-controlled trial | 90 | 90.9% | Effectiveness of an educational intervention | 3 |
| Weissman et al. 2001 [40] | US | Cross-sectional | 2626 | 65.3% | Mediating factors | 4 |
| Godkin et al. 2003 [41] | US | Non-controlled trial | 146 | 83.4% | Effectiveness of an educational intervention | 3 |
| Tavernier et al. 2003 [42] | US | Cross-sectional | 775 | 26.3% | Mediating factors | 4 |
| Schwartz & Loten, 2004 [43] | NZ, US | Cross-sectional | 1015 | NA | Change in MS-ATU | 4 |
| Wilson et al. 2004 [44] | US | Cross-sectional | 784 | 57% | Change in MS-ATU | 4 |
| Woloschuk et al. 2004 [45] | CA | Cohort | 198 | 52.5% | Change in MS-ATU | 2 |
| Ko et al. 2005 [20] | US | Controlled trial | 1088 | 93.6% | Effectiveness of an educational intervention | 2 |
| Cox et al. 2006 [46] | US | Randomized trial | 100 | 93% | Effectiveness of an educational intervention | 1 |
| Godkin et al. 2006 [47] | US | Controlled trial | 196 | 98.0% | Change in MS-ATU + Effectiveness of an educational intervention | 2 |
| Buchanan et al. 2007 [48] | US | Non-controlled trial | 25 | 100% | Effectiveness of an educational intervention | 3 |
| Crandall et al. 2007 [49] | US | Cohort | 110 | 71% | Change in MS-ATU + Effectiveness of an educational intervention | 2 |
| Ko et al. 2007 [50] | US | Case-control | 1071 | 100% | Effectiveness of an educational intervention + Mediating factors | 3 |
| Crandall et al. 2008 [51] | US | Cohort | 110 | 100% | Change in MS-ATU | 2 |
| Dyrbye et al. 2010 [52] | US | Cross-sectional | 2682 | 61% | Mediating factors | 4 |
| Huang & Malinow, 2010 [53] | US | Non-controlled trial | 46 | 100% | Effectiveness of an educational intervention | 3 |
| Wayne et al. 2011 [54] | US | Cohort | 313 | 59% | Change in MS-ATU | 2 |
| Scheu et al. 2012 [55] | US | Non-controlled trial | 274 | 75% | Effectiveness of an educational intervention | 3 |
| Boscardin et al. 2014 [56] | US | Cohort | 7631 | 58.8% | Mediating factors | 2 |
| Caulfield et al. 2014 [57] | US | Cross-sectional | 13,867 | 74.2% | Mediating factors | 4 |
| Smith et al. 2014 [58] | US | Non-controlled trial | 914 | 97.9% | Effectiveness of an educational intervention | 3 |
| Borracci et al. 2015 [59] | AR | Cross-sectional | 354 | 88.5% | Mediating factors | 4 |
| Cox et al. 2015 [60] | US | Randomized controlled trial | 137 | 88% | Effectiveness of an educational intervention | 1 |
| Jilani et al. 2015 [18] | US | Cross-sectional | 297 | 67% | Change in MS-ATU | 4 |
| Girotti et al. 2015 [61] | US | Case-control | 297 | 36% | Effectiveness of an educational intervention | 3 |
| Larkins et al. 2015 [62] | AU, BE, CA, PH, ZA, SD | Case-control | 944 | 88.9% | Effectiveness of selection strategies | 3 |
| Stephens et al. 2015 [63] | US | Cross-sectional | 170 | 35% | Change in MS-ATU | 4 |
| Laraque Arena et al. 2016 [64] | US | Cross-sectional | 1223 | 57% | Mediating factors | 4 |
| Leung et al. 2016 [65] | US | Non-controlled trial | 48 | 72% | Effectiveness of an educational intervention | 3 |
| Gatell et al. 2017 [66] | US | Cross-sectional | 393 | 66% | Mediating factors | 4 |
| Griffin et al. 2017 [14] | AU | Cohort | 351 | 94.6% | Mediating factors | 2 |
| O’Connell et al. 2017 [67] | US | Cohort | 564 | 70.4% | Change in MS-IWU + mediating factors | 2 |
| Puddey et al. 2017 [68] | AU | Cross-sectional | 2829 | 89.8% | Mediating factors | 4 |
| Tran et al. 2017 [69] | US | Controlled trial | 128 | NA | Effectiveness of an educational intervention | 2 |
| Briggs et al. 2018 [70] | US | Controlled trial | 42 | 88% | Effectiveness of an educational intervention | 2 |
| Garcia et al. 2018 [71] | US | Cross-sectional | 40,846 | 100% | Change in MS-IWU + Mediating factors | 4 |
| Kost et al. 2018 [72] | US | Case-control | 158 | 77% | Effectiveness of an educational intervention | 3 |
| Larkins et al. 2018 [21] | AU, BE, CA, PH, ZA, SD | Controlled trial | 3346 | 76.2% | Effectiveness of an educational intervention | 2 |
| Wolley et al. 2018 [73] | PH | Case-control | 492 | 45.5% | Effectiveness of selection strategies | 3 |
| Burkhardt et al. 2019 [74] | US | Cross-sectional | 17,067 | 91% | Mediating factors | 4 |
| Godfrey et al. 2019 [75] | US | Non-controlled trial | 59 | 84% | Effectiveness of an educational intervention | 3 |
| Heller et al. 2019 [76] | ZA | Non-controlled trial | 52 | NA | Effectiveness of an educational intervention | 3 |
| Jacobs et al. 2019 [77] | US | Non-controlled trial | 11 | 50% | Effectiveness of an educational intervention | 3 |
| Phelan et al. 2019 [78] | US | Cohort | 3756 | 64.5% | Change in MS-IWU | 2 |
a The quality of included studies was measured using the rating scheme modified from the Oxford Centre for Evidence-based Medicine23: the score is based on the design of the study (1 = randomized trial; 2 = controlled trial without randomization; 3 = case-control study or retrospective cohort study; 4 = cross-sectional study or case series)
Abbreviations: MS-ATU Medical students attitudes toward the underserved; MS-IWU Medical students intention to work with the underserved; AR Argentina; AU Australia; BE Belgium; CA Canada; NZ New Zealand; PH Philippines; ZA South Africa; SD = Sudan; US United States of America