Guest Column | May 12, 2017

How To Effectively Use Back Translation As A QA Tool For Clinical Trial Documents

By Cassandra Scott

How To Effectively Use Back Translation As A QA Tool For Clinical Trial Documents

Back translation is a powerful tool for ensuring that a clinical trial document has been accurately translated without loss of meaning; however, it is not the right QA tool for every project. The alternative is quality assessment performed by a professional translator, which will not be dealt with in this article but is important to mention as an option.

Limitations of Back Translation

The problem with back translation is that it requires a certain level of linguistic skill from the person using it as a QA tool. If that person is you, you should consider carefully whether you are in a position to assess whether the back translation is close enough to the original text. For example, in the case below, does the back translation show any cause for concern? In other words, are the two texts sufficiently similar in their meaning?

Normally, the differences between these two texts should not raise any red flags. Granted, the back translation is less concise than the original text; however, this is normal, as the purpose of a back translation is to reflect as far as possible the meaning of the translated text, not that of the original text. Nor does a back translation need to sound good. If you think carefully about what the two sentences mean, you see that there is no real difference. When you read these two sentences, did you feel that they were too different? If so, you may not be in a position to effectively use back translation as a QA tool for evaluating translations. The best option in this case would be to order a quality assessment. However, many CROs and sponsors have SOPs in place dictating that a back translation must be used.

Practical Tips For Using Back Translation Effectively

Whether you have decided that you would like to use a back translation, or you simply have to use one, here are some practical steps you can follow to ensure that you are using back translation effectively.

Understand the limitations of back translation.
Some errors in the “forward translation” may never be reflected in the back translation. After all, translation does not deal with words as such, but with meaning. Where there is no meaning, there can be no translation. Therefore, if the forward translation contains something that is essentially nonsense, this will be impossible to back translate. To deal with such cases effectively, you need to let the translator or LSP (language service provider) know a) that this is a back translation task; and b) that they can, and indeed should, annotate the back translation with any appropriate notes or queries regarding errors in the forward translation. Failing to ask for this as part of the service can cause you to miss serious errors. For example, if the translator does not know that they are doing a back translation, and instead thinks that they are doing a “normal” translation, they may simply infer or guess what was meant, and translate it “correctly.” In the context of an informed consent form, this could have serious consequences.

Consider the following scenario: The forward translation says that the prescribed dose is “100 g”. The person who is (unknowingly) performing the back translation sees that this dose is obviously incorrect, and that the author (unbeknownst to them, actually the “forward” translator) has simply left out the “m”. They therefore write “100 mg”. A good translator would inform you or the agency they are working for that there is a mistake in the source text. However, some LSPs/translators dislike pointing out their clients’ errors, for fear of embarrassing them, and subsequently losing them. If this is the case, and if the translator/LSP does not know that this is a back translation task, you may never be alerted that there is an error … which leads to the next point.

Be clear with your LSP or freelance translator about what you want from the back translation.
This may seem superfluous, but if you are using an LSP (i.e., a translation company/agency, as opposed to a freelancer), it is essential to explicitly state that the translator performing the back translation must be informed that the task is a back translation task and not a “normal” translation task. This should help avoid some of the pitfalls explained under Point 1. Again, many LSPs and translators are nervous about asking clients questions, for fear that if they ask too many questions, the client will begin to see them as an annoyance, and they will lose the client. Once again, this could lead to you not being alerted about errors in the translation. To avoid this, let the LSP or translator know that you are available to answer questions and, indeed, that you expect them to ask questions.

Another factor that you may wish to consider is terminology: If you have specific terminology that you would like the translator to use, you need to let them know. Lastly, consider whether you would like CAT (computer-assisted translation) tools and translation memories to be used. These tools allow translators to “recycle” old translations, which increases productivity and can help reduce costs. However, if the text that the translator is currently working on matches an old text very closely, there is a danger that they might reuse the old translation without looking at the new text (the text to be back translated) carefully enough, potentially causing some errors to be missed.

Communicate openly with your translator/LSP.
The lines of communication between the LSP/translator and you, the client, should always be kept open. If your provider delivers the back translation without any comments or questions, you should consider this a red flag. It may be that there really were no issues, and therefore nothing that they needed to ask, but it pays to double-check with them. Don’t be afraid to ask questions if you feel that there may be some issues — but be prepared to pay extra for a provider who is willing to take the time to answer your questions and provide detailed comments and explanations. When asking questions, or providing feedback, be clear that you are not making a complaint. Any perceived antagonism may result in an unhelpful breakdown of communication.


There are three main actions you can take to help ensure that you as the client get a back translation that does the job you want it to: understand the back translation process and its limitations, clearly express your expectations, and ensure consistent communication. This article focuses on what the client needs to do, though there are surely many ways in which service providers can serve clients better.

About The Author:

Cassandra Scott is an independent medical translator specializing in the translation of documents in the field of clinical trials, clinical research, and medicine. She gained her skills in this field in an in-house position at a German company whose end clients were some of the top CROs in Europe. She also has training in the principles of GCP (Good Clinical Practice), which gives her an in-depth understanding of this field. She offers German to English medical translations, including all language variants, such as Swiss German and Austrian German; and French to English translations, including all language variants, such as Swiss French. For more information or to contact Cassandra, visit