Table 1 Reviewers’ inclusion and exclusion criteria

1. English language from any country

1. Study findings not in English

2. Published 1950 or after

2. Prior to 1950 or abstracts not available

3. RCTs and quasi-experimental designs with parallel cohorts of control or comparison groups

3. Studies which were not RCTs or quasi-experimental designs, e.g., observational studies, moderator analyses

4. Services included health or mental health

4. Other human services

5. Described adaptation(s) intended to make services more responsive to or effective for diverse racial and ethnic populations; adaptations may target:

 • individual service provider OR

 • service system

5. Did not contain a description of the specific activities undertaken to improve cultural competence, appropriateness, or safety, and/or the study did not justify the inclusion of an adaptation with culturally-grounded rationale and/or existing research

6. Explicitly tested the effectiveness of the cultural adaptation separate from any other health or mental health intervention studied. This must result in intervention and control groups that differ only on the included cultural adaptation

6. Studies in which the cultural component and the health or mental health intervention were not evaluated separately from the other service provided. Also excluded studies that tested a generally used intervention to study its impact on a cultural, minority, ethnic, or disadvantaged population without adapting it to specifically suit the needs of the target population

7. Focus of study was on provision of a service

7. Studies that: only tested the translation of psychometric instruments, questionnaires, and diagnostic tools, focused on engaging visible minorities in research, or involved service delivery at some unspecified future time, such as genetic registries

8. Studies pertained to people and organizations in the mainstream culture making adjustments to include and serve those who are subject to inequity in service delivery or service outcomes

8. Service recipients did not represent a group subject to disparities in service delivery or outcomes, or target subjects’ data were confounded with those of another group that is not subject to health disparities and/or is not the target of the cultural adaptation under study

9. Reported outcomes that included:

 • change in service provider behavior OR

 • change in self-reported experience or outcomes of service recipient OR

 • change in observed outcomes for service recipient

9. Did not contain evidence of having measured outcomes of the adaptation to enhance cultural competence, appropriateness, or safety with specific reference to:

 • change in service provider behavior OR

 • change in self-reported experience or outcomes of service recipient OR

 • change in observed outcomes for service recipient

10. Outcomes and data were provided and analyzed in a way that allowed an evaluation of the direct results of the cultural adaptation

10. Outcomes and conclusions were not substantiated in the report with sufficient data

11. There were no flaws in the study methodology and/or delivery deemed likely to threaten the internal validity and interpretability of the study’s results

11. The research design, intervention delivery, or assessment of outcomes involved a confounding variable which threatens the internal validity of results, e.g., clinically meaningful differences between groups at baseline, lack of experimental control, inadequate statistical reporting, etc.