According to recent United States Census estimates, more than 25 million Americans have limited English proficiency (LEP), and many of these individuals are school-age children. Language barriers affect multiple aspects of healthcare for LEP patients, including access to care, health status, use of health services, and patient safety. LEP patients often defer needed medical care, have higher risks of leaving hospitals against medical advice, and are less likely to have a regular healthcare provider. They’re also more likely to miss follow-up appointments and to be non-adherent with medications.

“Medical interpreters are an essential component of effective communication between LEP patients and healthcare providers.”

Federal policy requires that hospitals provide adequate language assistance to LEP patients. Medical interpreters are an essential component of effective communication between LEP patients and healthcare providers. Professional interpreters are hired specifically to provide language services to LEP patients, but all too often, language services are provided by ad hoc interpreters. These individuals—who range from family members and friends to hospital/clinic employees and strangers from waiting rooms—are untrained in medical interpretation.

A New Comparison of Interpretation Methods

Previous studies have shown that family members and untrained bilingual people who provide ad hoc interpretation can commit many errors of interpretation. No investigation, however, has been conducted comparing these errors and their potential consequences in encounters with a focus on professional interpreters versus ad hoc interpreters or no interpreters. In the March 2012 Annals of Emergency Medicine, my colleagues and I had a study published in which we performed a cross-sectional error analysis of audiotaped ED visits during a 30-month period in the two largest pediatric EDs in Massachusetts. Participants included Spanish-speaking LEP patients, caregivers, and their interpreters.

In total, our study analyzed 57 encounters, 20 of which were with professional interpreters, 27 of which were with ad hoc interpreters, and 10 of which were with no interpreters. Overall, 1,884 interpreter errors were noted, 18% of which had potential clinical consequences, such as mistaking tablespoons for teaspoons of medicine. The proportion of errors of potential consequence was significantly lower for professional interpreters (12%), when compared with ad hoc interpreters (22%) and no interpreters (20%).

The Role of Interpreter Training & Experience

Another important finding from our study was that previous hours of interpreter training among professional interpreters was significantly associated with error numbers, types, and potential consequences. Professional interpreters who received at least 100 hours of training in medical interpreting had nearly two-thirds fewer errors than those with fewer than 100 hours of training. The median number of errors by professional interpreters with 100 or more hours of training was 12, compared with 33 for those with fewer than 100 hours of training.

Professional interpreters also had significantly fewer errors with clinical consequences than ad hoc interpreters. The proportion of errors with potential clinical consequences for professional interpreters with 100 or more hours of training was 2%, compared with 12% for interpreters with less than 100 hours of training.

Keeping Quality & Safety in Mind

Overall, our findings suggest that requiring at least 100 hours of training for interpreters might have a major impact on reducing interpreter errors and their consequences in healthcare. The analysis adds to the growing body of evidence that trained professional interpreters and bilingual clinicians are associated with optimal communication, patient satisfaction, quality of care, optimal outcomes, and patient safety.


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