Professionally trained medical interpreters

Evidence Rating  
Evidence rating: Scientifically Supported

Strategies with this rating are most likely to make a difference. These strategies have been tested in many robust studies with consistently positive results.

Health Factors  
Date last updated

Professionally trained medical interpreters provide interpretation services for patients with limited English proficiency (LEP) in outpatient and inpatient health care settings, and sometimes also serve informally as cultural liaisons or patient advocates. Interpreters are taught to interpret spoken words in the correct context via at least 40 hours of training, which often includes on-the-job training and courses in health care interpretation1. Language access services are mandated by Title VI of the Civil Rights Act for health care providers receiving federal funds, including Medicare and Medicaid. Professional interpreters may provide services in-person or remotely by telephone, often using a dual-handset interpreter telephone, or video conference2. Availability of professional interpreters is limited in many settings, often due to budgetary limitations. The use of ad-hoc interpreters such as untrained family, friends, or non-interpreter staff remains common3

What could this strategy improve?

Expected Benefits

Our evidence rating is based on the likelihood of achieving these outcomes:

  • Improved patient-provider communication

  • Increased patient satisfaction

Potential Benefits

Our evidence rating is not based on these outcomes, but these benefits may also be possible:

  • Improved health outcomes

What does the research say about effectiveness?

There is strong evidence that professionally trained medical interpreters improve patient-provider communication4, 5, 6 and increase satisfaction for patients with limited English proficiency (LEP), especially when services are provided in-person or over the telephone4, 5, 7, 8, 9. Additional evidence is needed to confirm effects on health outcomes5, 9, 10.

Professionally trained medical interpreters have been shown to make fewer clinically significant interpretation errors than untrained interpreters5, 7, 11, 12, 13 and are associated with improved quality of care for LEP patients4, 5, 7, 11, 14. Interpreters with 100 or more hours of training are less likely to make errors than interpreters with fewer hours of training11.

LEP patients who receive interpretation services from professionally trained medical interpreters are more likely to have preventive screenings, fill prescriptions, and successfully manage conditions such as diabetes than patients with ad-hoc interpreters such as family, friends, or health care staff untrained in interpretation5. In two New Jersey emergency departments, patients and providers report higher levels of satisfaction and better communication with in-person trained interpreters than ad-hoc or telephone interpreters8. A Denver-based study in a pediatric emergency department, however, indicates higher patient satisfaction with professional telephone interpreters than in-person professional interpreters15 and another study indicates parents of pediatric patients prefer professional telephone interpretation over ad-hoc interpreters or no interpretation16.

In-person professional interpretation may better support understanding of cultural nuances than interpretation via video-conference17. However, remote, real-time video-conferencing with professional interpreters may reduce errors12. Professional telephone interpretation is associated with reductions in interpreter-related delays in care18 and may increase the use of interpreters in acute care settings19.

A Boston-based study suggests that patients may prefer family members or friends serving as ad-hoc interpreters rather than engaging professionally trained interpreters20.

How could this strategy impact health disparities? This strategy is rated likely to decrease disparities.
Implementation Examples

Professionally trained medical interpreters are available in many health care settings, especially in non-profit hospitals in large, diverse urban areas21. Memorial Sloan Kettering Cancer Center, for example, offers a medical interpreting training program along with cultural responsiveness training22. The University of Texas MD Anderson Cancer Center’s international center provides professional medical interpretation services in Arabic, French, Mandarin, Spanish, Russian, Turkish, Vietnamese, and American Sign Language23. The University of California Davis Medical Center’s Department of Interpreting and Translation Services provides in-person, over-the-phone, and video conference interpretation in 18 languages as well as health care interpreter training courses24.

Professional interpreters can be certified by the Certification Commission for Healthcare Interpreters or the National Board of Certification for Medical Interpreters2. The Continuing Education Accreditation Program (CEAP) maintains a database of all professional medical interpretation programs certified by the Certification Commission for Healthcare Interpreters (CCHI)25.

Implementation Resources

Think cultural health - U.S. Department of Health and Human Services (U.S. DHHS), Office of Minority Health (OMH). Think cultural health: Guide to providing effective communication and language assistance services.

CCHI - Certification Commission for Healthcare Interpreters (CCHI). Eligibility Criteria.


* Journal subscription may be required for access.

1 CCHI - Certification Commission for Healthcare Interpreters (CCHI). Eligibility Criteria.

2 Juckett 2014 - Juckett G, Unger K. Appropriate use of medical interpreters. American Family Physician. 2014;90(7):476–480.

3 Galvez 2007 - Galvez E, Wilson-Stronks A. Hospitals, Language and Culture: A Snapshot of the Nation: Exploring Cultural and Linguistic Services in the Nation's Hospitals. The Joint Commission. The California Endowment. 2007.

4 Campbell-Wollscheid 2015 - Wollscheid S, Munthe-Kaas HM, Hammerstrøm KT, Noonan E. Effect of interventions to facilitate communication between families or single young people with minority language background and public services: A systematic review. Campbell Systematic Reviews. 2015:7.

5 Flores 2005 - Flores G. The impact of medical interpreter services on the quality of care: A systematic review. Medical Care Research and Review. 2005;62(3):255-299.

6 Lee 2017 - Lee JS, Pérez-Stable EJ, Gregorich SE, et al. Increased access to professional interpreters in the hospital improves informed consent for patients with limited English proficiency. Journal of General Internal Medicine. 2017:1-8.

7 Karliner 2007 - Karliner LS, Jacobs EA, Chen AH, Mutha S. Do professional interpreters improve clinical care for patients with limited English proficiency? A systematic review of the literature. Health Services Research. 2007;42(2):727-54.

8 Bagchi 2011 - Bagchi AD, Dale S, Verbitsky-Savitz N, et al. Examining effectiveness of medical interpreters in emergency departments for Spanish-speaking patients with limited English proficiency: Results of a randomized controlled trial. Annals of Emergency Medicine. 2011;57(3):248–256.e4.

9 Giordano 2007 - Giordano S. Overview of the advantages and disadvantages of professional and child interpreters for limited English proficiency patients in general health care situations. Journal of Radiology Nursing. 2007;26(4):126–131.

10 Karliner 2017 - Karliner LS, Pérez-Stable EJ, Gregorich SE. Convenient access to professional interpreters in the hospital decreases readmission rates and estimated hospital expenditures for patients with limited English proficiency. Medical Care. 2017;55(3):199-206.

11 Flores 2012 - Flores G, Abreu M, Barone CP, Bachur R, Lin H. Errors of medical interpretation and their potential clinical consequences: A comparison of professional versus ad hoc versus no interpreters. Annals of Emergency Medicine. 2012;60(5):545–553.

12 Napoles 2015 - Nápoles AM, Santoyo-Olsson J, Karliner LS, Gregorich SE, Pérez-Stable EJ. Inaccurate language interpretation and its clinical significance in the medical encounters of Spanish-speaking Latinos. Medical Care. 2015;53(11):940-947.

13 Bauer 2010 - Bauer AM, Alegría M. The impact of patient language proficiency and interpreter service use on the quality of psychiatric care: A systematic review. Psychiatric Services. 2010;61(8):765-773.

14 Rosenberg 2008 - Rosenberg E, Seller R, Leanza Y. Through interpreters’ eyes: Comparing roles of professional and family interpreters. Patient Education and Counseling. 2008;70(1):87–93.

15 Crossman 2010 - Crossman KL, Wiener E, Roosevelt G, Bajaj L, Hampers LC. Interpreters: Telephonic, in-person interpretation and bilingual providers. Pediatrics. 2010;125(3):e631-e638.

16 Cunningham 2008 - Cunningham H, Cushman LF, Akuete-Penn C, Meyer DD. Satisfaction with telephonic interpreters in pediatric care. Journal of the National Medical Association. 2008;100(4):429-434.

17 Napoles 2010 - Nápoles AM, Santoyo-Olsson J, Karliner LS, et al. Clinician ratings of interpreter mediated visits in underserved primary care settings with ad hoc, in-person professional, and video conferencing modes. Journal of Health Care for the Poor and Underserved. 2010;21(1):301-317.

18 Lion 2015 - Lion KC, Ebel BE, Rafton S, et al. Evaluation of a quality improvement intervention to increase use of telephonic interpretation. Pediatrics. 2015;135(3):e709-e716.

19 Tuot 2012 - Tuot DS, Lopez M, Miller C, Karliner LS. Impact of an easy-access telephonic interpreter program in the acute care setting: An evaluation of a quality improvement intervention. The Joint Commission Journal on Quality and Patient Safety. 2012;38(2):81-88.

20 Ginde 2010 - Ginde AA, Sullivan AF, Corel B, Caceres JA, Camargo CA. Reevaluation of the effect of mandatory interpreter legislation on use of professional interpreters for ED patients with language barriers. Patient Education and Counseling. 2010;81(2):204–206.

21 Schiaffino 2014 - Schiaffino MK, Al-Amin M, Schumacher JR. Predictors of language service availability in U.S. hospitals. International Journal of Health Policy and Management. 2014;3(5):259–268.

22 MSKCC-Medical interpreting - Memorial Sloan Kettering Cancer Center (MSKCC). Immigrant Health & Cancer Disparities Service. Medical interpreting training program.

23 UTMDACC-International center - The University of Texas MD Anderson Cancer Center (UTMDACC). International center. Certified medical interpreters.

24 UCDMC-Interpreting - University of California Davis Medical Center (UCDMC). Department of Interpreting and Translation Services.

25 CEAP-CCHI providers - Continuing Education Accreditation Program (CEAP). Certification Commission for Healthcare Interpreters (CCHI). Find a health care interpretation provider.