The overall goal of this randomized clinical trial is to learn about the effects of a parent-mediated intervention (PMI) designed to support communication outcomes for deaf and hard-of-hearing (DHH) children. Previously, the investigators enrolled 96 DHH children between 12 and 18 months of age and their parents. Families were randomly assigned to receive either the PMI or a business-as-usual control group. The PMI was a 6-month intervention that included weekly, hour-long Zoom sessions. During the intervention sessions, parents were taught communication support strategies to support their child's language development throughout daily routines and play.

This current period of the trial follows the same children into early elementary school to determine whether the effects of the PMI are long-lasting. The main questions it aims to answer are:

• Does the PMI improve language, reading, and social communication outcomes in the early school years?
• Does parent involvement during early intervention support continued engagement in their child's education?

The investigators will compare parents and children who received the PMI to those in the business-as-usual control group to determine whether the intervention has lasting effects on these outcomes.

Participants will complete standardized assessments, parent-report surveys, and video-recorded naturalistic interactions. All assessments will be completed remotely.

Hearing loss is one of the most prevalent congenital conditions. Recent advances in early detection and technology have contributed to significant improvements in long-term outcomes for deaf/hard-of-hearing (DHH) children. Despite this progress, language and literacy outcomes for school-age DHH children are inconsistent, and many DHH children do not "catch up" to their hearing peers. Closing this gap requires the implementation of effective early communication interventions. Yet, until recently, there was a significant paucity of research on early communication interventions for DHH children. Parent-mediated interventions (PMIs), which involve teaching parents strategies to enhance their child's language learning experiences, are a promising form of early intervention for DHH toddlers. During the previous project period (NCT03803943), 96 DHH children, between 12 and 18 months of age and their parents, were enrolled. Parent-child dyads were randomly assigned to receive either the PMI or business-as-usual control group. The investigators examined the effects of the intervention on (a) parent strategy use and (b) child communication outcomes during and after the 6-month intervention period. The follow-up period of the clinical trial is outlined here.

This trial will be the first large-scale evaluation of the long-term effects of an early communication intervention on school-age language and literacy outcomes for DHH children. The study enrolled 96 parent-child dyads, 88 of whom remain involved and consented to contact for the follow-up period. The investigators will complete follow-up assessments during early elementary school. The investigators plan to examine the long-term effects of the intervention on school-age outcomes and characterize the intermediary mechanisms of these effects. The investigators consider not only how early communication interventions affect subsequent child outcomes, but also how involving parents early in their child's development may lay the foundation for sustained parent engagement as children transition to school-based services. Taken together, the investigators plan to integrate child and parent outcomes to fully characterize how early language learning experiences shape long-term language and literacy outcomes. Understanding the pathways through which early interventions affect the developmental trajectory of DHH children will have widespread implications for research and clinical practice.

Eligibility for the follow-up period of the clinical trial is dependent on enrollment in the initial period of the clinical trial.

Child inclusion criteria were:

• between 12-18 months
• diagnosed with bilateral hearing loss
• no additional diagnoses (e.g., Down syndrome, cerebral palsy, seizure disorder, blindness, etc.)
• one parent with typical hearing
• exposed to some degree of spoken language by their parents.

All participant-level data related to the primary and secondary outcomes of the clinical trial will be preserved and shared via Dryad. All shared data will be de-identified by using a unique study identifier and age in months rather than date of birth. This will allow for the replication of all analyses for the primary aims and for other investigators to answer other questions that are not related to the study aims. The final results of the study will be uploaded to clinicaltrials.gov.

All data as described above will be shared, as allowed by informed consents. The only data that will not be shared are the video recordings of the observational peer-peer and parent-child interactions, which contain participants' faces.

Data will be made available no later than the time of publication of the main study aims or the end of the project period, whichever comes first. Data will be stored and available via Dyrad in perpetuity.

Dryad datasets are indexed by the Thomas-Reuters Data Citation Index, Scopus, and Google Dataset Search. Dyrad gives each dataset a unique Digital Object Identifier, which when entered into any browser will take the user to the landing page of the dataset.

Outcome assessors and coders will be naive to the experimental condition