Long-term outcomes of cochlear implantation in early childhood: sample characteristics and data collection methods

This article describes participants in a follow-up study of a nationwide sample of children who had used a cochlear implant (CI) since preschool. The children were originally tested when they were in early elementary grades, and results were published in a monograph supplement of Ear and Hearing. Recently, many of these children returned for follow-up testing when they were in high school with >10 yrs experience with a CI. This introductory article will (1) discuss the extent to which the sample tested is representative of typical populations and (2) describe how sample characteristics changed over time for the 112 students tested in both elementary grades and high school.

Over a 4-yr period, 112 teenagers from across North America, accompanied by a parent, attended a research camp that was similar to one in which they had participated 8 yrs earlier. A battery of auditory, speech, language, and reading tests was administered, and responses to questionnaires and written language samples were obtained and are described in the following articles in this issue. This article summarizes child, family, and educational characteristics that were quantified so that their role in outcome levels achieved could be examined statistically. For example, metrics were devised to reflect the extent to which a student's language improved when sign language was added to spoken language (i.e., sign enhancement) based on test results obtained in elementary grades and in high school.

Comparisons of early characteristics of the 112 students who returned for follow-up testing with the 72 who did not return indicated comparable Performance Intelligence Quotients, communication mode ratings, family education/income, and age at implant. However, follow-up participants had better speech perception, speech intelligibility, and language skills at 8 or 9 yrs of age. Seventy-five percent of returning teenagers were fully mainstreamed in high school (compared with 63% in elementary grades). Only 5% of adolescents were in full-time special education. Grade placement of the teenagers was appropriate to their chronologic age. Estimates of sign enhancement, family characteristics, and Performance Intelligence Quotient were consistent over the two test sessions.

A large proportion of the original sample returned for follow-up testing in adolescence, but they were a more selective group than nonreturning subjects, and their scores may overestimate long-term CI outcomes for the general population. On the other hand, CI-HS students who participated in this study received their device >10 yrs ago and did not have some of the advantages available to more recently implanted children, so their results may underestimate those outcomes.