I think the title says it all, and it’s an important question. There’s no doubt that the best way to determine if a child has a language impairment is to test them in their language. For bilinguals, that usually means two languages– in the US context, their home language and English. But, there aren’t enough bilingual speech-language pathologists available nationally; and bilingual speech-language pathologists don’t speak every language represented by the clients in their area. So, one of the questions we’ve had is whether we can get any useful information from testing children who are bilingual in English only. The quick answer is yes, no, and it depends. The longer answer follows.
We have a new paper in press in JSLHR called Identification of Specific Language Impairment in Bilingual Children, Part 1: Assessment in English. In this paper we followed 167 kids from our Diagnostic Markers study for two years after we screened them before kindergarten. These kids were selected into the study from the original 1200 because they used both Spanish and English at least 20% of the time, and because they scored below the 30th percentile on one screening measure in Spanish and one in English. So, we had a group of kids some of whom were likely to have language impairment; and others who had mixed dominance, but typical development, but who might be likely to be referred because they demonstrated patterns of strengths and weaknesses that were inconsistent.
We tested this group of kids on a battery of measures in English and Spanish, and in this study we present the English results. Of the group of children, 21 were identified with language impairment by 3 very experienced bilingual SLPs. We used this as the gold standard measure against to test how well a battery of measures that included the TOLD-P subtests and the TNL together differentiated bilingual children with and without language impairment.
Using cutscores set for monolingual English speakers, we found 95% sensitivity and 45% specificity. This means that the criteria identified most of the kids with LI as having LI, and a bunch of the typical kids as LI too. So, here the answer is no, English testing doesn’t do a very good job at identification of LI in bilinguals.
We then looked at whether we could set new cut points. That led to improvment, but we still over identified bilinguals with LI. Then we used regression modeling to optimize the classification and using these optimized curves were able to obtain improved classification to 81% sensitivity and 81% specificity. So, yes, we do get some useful information. In the paper, we provide the formula for calculating the probability that the child has language impairment based on the TNL and the TOLD-P:3 subtests. Using this formula is an improvement over a cut-off score approach. Also, we recommend that children need to have at least 30% regular exposure to English. Kids who have less exposure to English than that are likely to be misdiagnosed. So, here the “yes, we can get good information from English testing” is moderated by “it depends.”
It’s better, but 81% correct classification still means there’s 19% error, so we’d like to improve on that. Our next study looks at whether testing in both languages can improve our diagnostic accuracy even further. I’m betting it can– that will be part 2.