International Journal of Pediatric Otorhinolaryngology 79 (2015) 196–201 Contents lists available at ScienceDirect International Journal of Pediatric Otorhinolaryngology jo urnal homepage: www.elsevier.com/locate/ijporl Does the introduction of newborn hearing screening improve vocabulary development in hearing-impaired children? A population-based study in Japan a,c a, c b b,d Shuhei Ohmori , Akiko Sugaya *, Naomi Toida , Etsuji Suzuki , Masato Izutsu , c a a a,e Tomoko Tsutsui , Yuko Kataoka , Yukihide Maeda , Kunihiro Fukushima , a Kazunori Nishizaki a Department of Otolaryngology, Head & Neck Surgery, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan b Department of Epidemiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan c Okayama Kanariya Gakuen, Auditory Center for Hearing Impaired Children, 321-102, Nisifurumatsu, Kita-ku, Okayama 700-0927, Japan d Health Policy Bureau, Ministry of Health, Labour and Welfare, 1-2-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8916, Japan e Shinkurasiki Ear, Nose, and Throat Clinic, 3-120-1 Shinkurashikiekimae, Kurashiki-shi, Okayama 710-0253, Japan A R T I C L E I N F O A B S T R A C T Article history: Objective: Permanent hearing impairment has a life-long impact on children and its early identification is Received 26 July 2014 important for language development. A newborn hearing screening (NHS) program has started in Received in revised form 8 December 2014 Okayama Prefecture, Japan, in 1999 to detect hearing impairment immediately after birth. We aim to Accepted 8 December 2014 examine the effect of this screening program on vocabulary development in pre-school children in a Available online 16 December 2014 before and after comparative study design. Methods: A total of 107 5-year-old children who graduated from Okayama Kanariya Gakuen (an auditory Keywords: center for hearing-impaired children) between 1998 and 2011 were enrolled in this study. The pre-NHS Newborn hearing screening group (n = 40) was defined as those who graduated between 1998 and 2003, while the post-NHS group Vocabulary (n = 67) was defined as those who graduated between 2004 and 2011. The primary outcome was Language development Hearing impairment receptive vocabulary, which was assessed by the Picture Vocabulary Test [score <18 (low) vs. score 18 (high)]. The secondary outcome was productive vocabulary, or the number of productive words, which was assessed by an original checklist [<1773 words (low) vs. 1773 (high)]. We calculated odds ratios and 95% confidence intervals for vocabulary development and compared both groups. Results: The adjusted Picture Vocabulary Test score and number of productive words were significantly higher (p < 0.01) in the post-NHS group than the pre-NHS group. Odds ratios were 2.63 (95% confidence interval: 1.17–5.89) for receptive vocabulary and 4.17 (95% confidence interval: 1.69–10.29) for productive vocabulary. Conclusions: The introduction of NHS in Okayama Prefecture significantly improved both receptive and productive vocabulary development in hearing-impaired children. ß 2014 Elsevier Ireland Ltd. All rights reserved. 1. Introduction [1–3]. Late identification of PCHI in children results in language delay and consequently affects their performance in academics or Permanent childhood hearing impairment (PCHI) has a lifelong other activities. Thus, the social and economic impact of PCHI is influence on language development in hearing-impaired children immeasurable and great effort has been put into its early identification. Recent progress in newborn hearing screening (NHS) has enabled hearing impairment to be identified just after birth and has therefore led to early diagnosis of PCHI [4–7]. * Corresponding author. 2-5-1, Shikata-cho, Kita-ku, Okayama 700-8558, Mishina et al. [8] organized an NHS research group in Japan in Tel.: +81 86 235 7307; fax: +81 86 235 7308. E-mail address: [email protected] (A. Sugaya). 1998 and in 2000, they developed practical guidelines for NHS. http://dx.doi.org/10.1016/j.ijporl.2014.12.006 0165-5876/ß 2014 Elsevier Ireland Ltd. All rights reserved. S. Ohmori et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 196–201 197 Although the official NHS program in Japan started in 2001, actual hearing devices (HA or CI). The training program was given by the arrangements for implementing the program began in several speech–language–hearing therapists and teachers in a bottom-up districts, including Okayama where the first NHS system was approach. We applied a before and after comparative study design. prepared in 1999 [9]. Although more than a decade has passed Five-year-old children who graduated from Okayama Kanariya since the program’s initiation, no quantitative studies have been Gakuen between the 1998 and 2003 academic years were defined as conducted to date to examine its effects. the pre-NHS group and the 5-year-old children who graduated Accordingly, we planned this study to examine the effects of between the 2004 and 2011 academic years were defined as the NHS on language development in hearing-impaired children since post-NHS group (Fig. 1). The children were divided into these two its introduction in Okayama Prefecture. We examined vocabulary groups with 2003 as the dividing line because no graduates development as a measure of language because vocabulary is an received NHS prior to 2003 while a considerable portion of the important language domain that develops in children of all school graduates after 2004 did receive NHS (Table 1). The aim of this study ages, and it is one of the most fundamental abilities of language. was to evaluate the total change in one particular district as a result Vocabulary consists of receptive vocabulary (i.e., how children of the introduction on NHS rather than a personal change after understand the meaning of spoken words) and productive receiving NHS. Because the introduction of NHS is technically a vocabulary (i.e., how children voluntarily speak words). We political decision, changes were evaluated in a district-based study. hypothesized that the introduction of NHS contributed to better This study was approved by the Okayama University ethics development of both receptive and productive vocabulary in commission on November 27, 2012. children with PCHI. 2.2. Measures 2. Participants and methods As a primary outcome measure, we assessed receptive 2.1. Study design vocabulary by using the Picture Vocabulary Test (PVT), which is a localized version of the Peabody Picture Vocabulary Test for Children who entered Okayama Kanariya Gakuen between the Japanese language users. In this test, the children were seated 1993 and 2011 academic years were enrolled in this study. facing a speech language therapist in a sound-attenuated chamber Okayama Kanariya Gakuen is an auditory center for hearing- and scored according to the test manual. Children receiving impaired children which was established in Okayama, Japan in PVT-adjusted scores 18 were considered to have demonstrated 1969; this center uses the auditory-verbal method in children with age-appropriate vocabulary development according to the man- hearing aids or cochlear implants from age 0 to 6 years [10]. The ufacturers’ instructions for the test [11]. Thus, we divided the children received 60 min of individual and 60 min of group subjects into a lower receptive vocabulary group (scores <18) and auditory-verbal training for two to three times a week using their higher receptive vocabulary group (scores 18). Pre-NH S group Post-NHS group n=83 n=127 Left Okayama Did not agree to participate in KanariyaGakuen halfway the stud y(n=6) through the stud y period (n=38 ) Left Okayama Kana riyaGakuen halfway through the stud y period Reasons: (n=45 ) Entered school for the deaf: n=19 Reasons: Chang ed institutions: n=9 Entered schoo l for the deaf: n=21 Foun d to have normal Chang ed institutions: n=8 hearing : n=7 Mov ed to another prefecture: n=4 Foun d to have normal hearing: n=76 n=45 n=2 Other: n=10 Could not perform Could not perf orm PVT PVT because of bec ause of intellectual intellec tual chall enges chall enges n=5 n=9 n=40 n=67 Fig. 1. Participant flow. PVT: Picture Vocabulary Test. 198 S. Ohmori et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 196–201 Table 1 107 children were included in the final analyses. Table 2 shows the NHS participation in the children in this study. characteristics of the participants. The male to female ratio was Academic year Graduated Number of NHS (%) similar in the pre-NHS and post-NHS groups. Significantly earlier of graduation children (n = 121) participants commencement of hearing aid use and eventually longer periods of 1998 4 0 0 preschool training were observed in the post-NHS group, reflecting 1999 12 0 0 the earlier identification of hearing loss after the introduction of NHS 2000 9 0 0 (Table 2). 2001 5 0 0 2002 8 0 0 3.2. Correlation between adjusted PVT scores and the vocabulary 2003 7 0 0 2004 7 5 71 checklist 2005 5 1 20 2006 6 1 17 The vocabulary checklist results were significantly correlated 2007 8 4 50 with the adjusted PVT scores (r = 0.747, p < 0.001). 2008 11 9 82 2009 10 9 90 2010 16 15 94 3.3. Comparisons between the pre-NHS and post-NHS groups 2011 13 11 85 3.3.1. Primary outcome: receptive vocabulary Fig. 2A and B shows the distribution of the adjusted PVT scores. The post-NHS group clearly demonstrated better scores (mean As a secondary outcome measure, productive vocabulary Æ standard deviation: 19.76 Æ 8.31) than the pre-NHS group measured by an original vocabulary checklist created by Okayama (14.83 Æ 7.62) (p = 0.003).