Autism-risk screening in the first 3 years of life in Taiwan Birth Cohort Pilot Study
Research highlights
► Using the M-CHAT, 292 (18.0%) children were screened out as being at high risk for ASD, and with the M-CHAT as the lead criteria, the cutoff points for the TBCS 6, 18, and 36 months’ developmental scales were determined as 65/66, 42/43 and 51/52, respectively. ► With the cutoff points, TBCS developmental instrument can be used as a community-based first-stage screening instrument at 6, 18, and 36 months. ► Early diagnosis and intervention optimizes the long-term prognosis of ASD and may also prevent over-referrals and free the parents and families of unnecessary concerns.
Introduction
Autism spectrum disorder (ASD) is defined by deficits in the three main areas of reciprocal social interaction, communication, and restricted and repetitive behaviors and interests (American Psychiatric Association, 1994). ASD used to be considered a rare event, with an estimated prevalence rate of 6.7 per 1000 (Centers for Disease Control and Prevention, 2007). However, a study in Taiwan found that 34 out of 1000 children listed in the National Health Insurance Program database were diagnosed with ASD, revealing a 14% increase in the incidence rate (Chen, Liu, Su, Huang, & Lin, 2007). In addition to Taiwan, the prevalence of ASD has increased dramatically in the United States, as well (Gurney et al., 2003). With this increase in the prevalence of ASD, screening and surveillance is of vital importance.
Many studies have found that early diagnosis and intervention optimizes the long-term prognosis for ASD (Lord, 2000), and also decreases family stress (Scahil, 2005). However, gaps were found among the parent's first concern about their children's behavior, the age of first evaluation and the final diagnosis (Siegel, Pliner, Eschler, & Elliott, 1988). Therefore, autism-specific screening tools, such as the Modified Checklist of Autism in Toddlers (M-CHAT) have been developed, and have been found to be effective in identifying those at risk for ASD in clinical (Robins, Fein, Barton, & Green, 2001) and primary care settings (Robins, 2008). However, its effectiveness as a community-based screening for ASD has shown inconsistent results (Perera, Wijewardena, & Aluthwelage, 2009).
A two-stage screening method may be more suitable in a community-based setting, since it entails using a less expensive, less invasive test at the first stage, and a more expensive or more invasive, but more sensitive and specific test at the second stage (Gordis, 1996). An example of this method used in the screening of development and ASD is described in Lung et al. (2011). The first stage uses a broadband instrument which assesses all developmental domains (e.g., Parents’ Evaluation of Developmental Status), then a narrowband focusing on a single domain or condition for the second stage (e.g., M-CHAT). Using this screening approach, only a portion of the children need to be further assessed at the second stage, thus the prevalence of the disease is enhanced, which would increase the positive predictive value (PPV; the proportion of true positives among individuals who tested positive) of the instrument and provide better accuracy in predicting the disease (Gordis, 1996). In addition, time, human resources and money may be saved (Chien, Huang, & Lung, 2009). These savings are essential in a community-based screening, since a large number of children will need to be screened in these settings.
The Taiwan Birth Cohort Study (TBCS) developmental instrument is a broadband screening instrument that has been found to be reliable, valid and effective in community screening for developmental delay in a national birth cohort study (Lung et al., 2008, Lung et al., 2010). However, broadband screening instruments have been criticized for their over-referral (Glascoe, Macias, Weqner, & Robertshaw, 2007) and failure to detect a portion of those with ASD (Pinto-Martin et al., 2008). These limits maybe minimized using a two-stage screening approach.
The TBCS developmental instrument has been found to be applicable in large-scale community screening in Taiwan (Lung et al., 2008, Lung et al., 2010), and the M-CHAT has been found to be applicable to the Chinese population (Wong et al., 2004). Hitherto, no studies have tested the use of the M-CHAT in randomized community-based screening for ASD. Therefore, this study used a randomized community-based birth cohort sample to investigate whether the TBCS can be used as a first-stage broadband screening instrument in the detection of ASD at 6, 18, and 36 months. In addition, using the M-CHAT as the lead criteria, the cutoff points for the TBCS developmental instrument in the screening of ASD were investigated.
Section snippets
Participants
This study used the dataset from the Taiwan Birth Cohort Pilot Study (TBCS-P), a national birth cohort study of a sample of infants born between November and December 2003. Two-stage stratified random sampling using the township as the primary sampling unit (PSU) was carried out. In the first-stage sampling, 29 out of 369 townships were chosen, using the systematic random sampling method. The next stage involved selecting individual cases by random sampling from the national birth report
Results
The demographics of the infants and their parents are shown in Table 1. Of the 1618 children, about half were male (n = 888, 54.9%). The mean age of the fathers was 37.87 ± 5.34 (range 21–26) years, and that of the mothers, 33.92 ± 4.84 (range 22–50) years.
With the M-CHAT, two different criteria were used to screen out those possibly at high risk for ASD. Using the first criteria of 3 out of all 23 items, 292 (18.0%) of the children were screened out, and 24 (1.5%) were screened out using the second
Discussion
Using the M-CHAT, 292 (18.0%) children were screened out as being at high risk for ASD, and with the M-CHAT as the lead criteria, the cutoff points for the TBCS 6, 18, and 36 months’ developmental scales were determined as 65/66, 42/43 and 51/52, respectively. The NPVs of the three scales were 83.44%, 84.21% and 85.35%, all above 80%. Overall, the TBCS developmental scales were shown to be an efficient first-stage broadband screening instrument for ASD at 6, 18 and 36 months in a
Acknowledgement
This study was supported by grants from the Bureau of Health Promotion (DOH93-HP-1702, DOH94-HP-1802, DOH95-HP-1802, DOH96-HP-1702).
The views expressed herein are the authors’ own. The study has relied on the work of many colleagues. We also thank the families who gave us such generous cooperation at all the stages of the study.
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