Using Propensity Score Matching to Address Clinical Questions: The Impact of Remote Microphone Systems on Language Outcomes in Children Who Are Hard of Hearing

Abstract

Purpose Children who are hard of hearing (CHH) have restricted access to acoustic and linguistic information. Increased audibility provided by hearing aids influences language outcomes, but the benefits of hearing aids are often limited by acoustic factors and distance. Remote microphone (RM) systems further increase auditory access by reducing the negative consequences of these factors. The purpose of this article was to identify factors that influence likelihood of RM system receipt and to investigate the effects of RM systems in home settings on later language outcomes. We used propensity score matching to compare language outcomes between children with and without access to personal RM systems in home settings. This article provides a description of how and why to perform propensity score–matching analyses with clinical populations. Method Participants were 132 CHH. Through parent report, we identified children who received RM systems for home use by 4 years of age. Logistic regression was used to determine factors that predict likelihood of RM system receipt in home settings. Propensity score matching was conducted on a subgroup of 104 participants. Performance on language measures at age 5 years was compared across propensity-matched children who did and did not receive RMs for personal use. Results Likelihood of RM receipt was associated with degree of hearing loss, maternal education, and location (recruitment site). Comparisons between matched pairs of children with and without RM systems in early childhood indicated significantly better discourse skills for children whose families owned RM systems, but no significant differences for vocabulary or morphosyntax. Conclusion Results provide preliminary evidence that the provision of personal RM systems for preschool-age CHH enhances higher-level language skills. The propensity score–matching technique enabled us to use an observational, longitudinal data set to examine a question of clinical interest.