In this study, we found that the AUC of CARS was larger than that of ABC. This finding suggests that CARS is better than ABC in terms of its diagnostic validity for suspected ASD. We also found that the cut-off scores of CARS and ABC for suspected ASD were 34 and 67, respectively. Sensitivity and specificity values included in criterion-validity measures are known to be particularly helpful in clinical settings[22]. The results of a t-test on the specificities between these two assessments also revealed a significant difference, indicating that the specificity of CARS was higher than that of ABC. Furthermore, we verified that the Cronbach alpha coefficient of CARS was 0.772, while that of ABC was 0.426. This finding suggests that CARS may be more suitable for diagnosing suspected ASD.
CARS is one of the most important tools for the assessment of ASD, such that both clinical and research practices often use it[23]. Recently, CARS-2 was exploited based on the original edition of CARS[24]. CARS-2 (normalized form) is the same as original CARS, whereas CARS-2-HF (high-functioning form) is a newly developed optional diagnostic for evaluating ASD in children over a certain age and with IQ scores above 80[25]. In this study, we revisited the validation of CARS and found that it functioned as a better diagnostic compared with that of ABC. We also identified an updated cut-off score of CARS for its further usage in diagnosing suspected ASD.
One of the advantages of our study is the introduction of the concept of suspected ASD, which differs from concepts offered in previous studies. In China, there are an increasing number of suspected ASD that have been identified at community health-service centers and preschools[17]. It has been reported that early diagnosis plays a critical role for improving outcomes of ASD[26]. In this context, preliminary screening tools are a critical step for timely diagnosis and intervention of ASD[27]. As a preliminary screening tool, CABS can help childcare physicians, teachers, and parents to quickly screen children with suspected autism[8].
Moreover, most children with suspected ABC require further assessments, such as via ABC and/or CARS. Based on the results of our present study, we suggest that CARS may be sufficient for further assessment of suspected ASD.
Previous studies have suggested that the cut-off scores of CARS and ABC for distinguishing autism and non-autism are 30 and 68, respectively[13, 14]. However, for patients with suspected ASD, it has been suggested that these previously proposed cut-off values may no longer be accurate. Based on the results of the present study, we suggest new cut-off value of CARS (namely, a score of 34) for the diagnosis of suspected ASD. Based on our present findings, we suggest that children with suspected ASD be initially screened via CABS and that any suspected cases be further confirmed via CARS.
Based on clinically suspected children with ASD in this present study, we found that the diagnostic validation of CRAS was better than that of ABC. Although previous studies have confirmed the strength of CARS, the sample sizes have been limited[8]. In the present study, we confirmed that CARS may be more suitable than ABC for diagnosing ASD in China, especially for suspected ASD[28].
The only available means of ASD diagnosis are behavioral assessments rather than blood tests or non-invasive assessments[29]. Furthermore, in order to conduct the most comprehensive evaluation of ASD, different measurement tools are required in different assessment environments. CARS is a valid and reliable assessment tool that is used for diagnosis and screening ASD in a number of countries[30]. As mentioned above, the main purpose of this study was to explore the diagnostic validation of CARS in a large Chinese sample. Our results further confirmed that CARS is able to effectively and efficiently diagnose patients with suspected ASD. Therefore, in order to comprehensively evaluate ASD, we recommend the combined use of CABS and CARS which might improve the efficiency of clinical works in hospitals.
Our study had two specific limitations: first, the age range of included parents was large (aged 1.5–14 years), future studies should clarify the diagnosis validation of ABC and CARS in different age groups. Second, CARS is a clinician-based rating scale, whereas ABC and CABS are both self-rating scales[25, 31]. Due to some parents being reluctant to face the fact that their children might have ASD, this caveat may have affected the final ABC and CABS scores associated with this study.