Recently reported prevalence of autism spectrum disorders (ASD) is 1-2% in Japan (Kamio et al., 2010; Kawamura, Takahashi, & Ishii, 2008) and the U.K. (Baird et al., 2006; Baron-Cohen et al., 2009). The Japanese government has started to promote health-social policy of early detection and intervention for children with ASD and their families. In Japan, although the child health checkup system from infants to 3-year-olds has been well established nationwide and the visit rate is over 90%, the 18- and 36-month checkups focus on language/intellectual development but not social development. Because socio-communication abnormalities begin to manifest at 1 year of age in ASD, the checkup at 18 months appears to provide a good opportunity to detect early symptoms of ASD. We considered that the Modified Checklist for Toddlers with Autism (M-CHAT), a 23-item, parent-report questionnaire (Robins et al., 2001), may complement and enhance the existing checkup system, since the checklist was developed for children 16-30 months of age and is easy to administer without increasing the burden on both the families and check-up staff. For these reasons, we developed the Japanese version of the M-CHAT. After a preliminary study (Kamio & Inada, 2006), with the permission of the authors, we added illustrations (items 7, 9, 17, and 23: see www.mchatscreen.com) to help caregivers to recognize negative symptoms.
Objectives:
To examine whether the early ASD screening procedure using the Japanese M-CHAT (J-MCHAT, Inada et al., 2010) is effective when it is added to 18-month checkup in Japan similarly as in the U.S.
Methods:
2113 children (94.2% of the total population, males 50.7%) who visited the 18-month health check-up (97.5% were between 18-19 months of age) in a suburb of Fukuoka, Japan were screened using the J-MCHAT with a 2-stage procedure, a parent-administered 23 item questionnaire screen and the M-CHAT Follow-up Interview (FUI) by telephone. We lowered the threshold at the 1st screening due to the younger age such that a child screened positive if he/she failed 3/23 or 1/10 critical items. 312 children were screen-positive at the 1st stage, and 42 children stayed positive at the 2nd stage and were invited for a developmental evaluation at age 2. A subgroup of screen-positive children and screen-negative children under the community health surveillance system were invited to developmental/diagnostic evaluations at 2, 3, 4, 5, 6 years of age, and each case received evaluations more than twice. Probable ASD was considered when a child was evaluated at 2 and showed ASD symptoms, did not attend follow-up evaluation, but surveillance at kindergarten or elementary school entry indicated likely ASD.
Results:
Twenty-nine children of 39 children later diagnosed as ASD/probably ASD were screen-positive at the 1st and 20 children were positive at the 2nd screening. Psychometrics for J-MCHAT alone are sens=.74, spec=.91, PPV=.15, and NPV=.99. When the J-MCHAT + FUI is considered, sens=.56, spec=.99, PPV=.69, and NPV=.99.
Conclusions:
With a few modifications of threshold criteria according to age, the M-CHAT screening can successfully differentiate children with ASD from the other children at 18 months.