In the present study, the CY-BOCS showed good consistency in the two-factor structure. The “obsession” and the “compulsive” factors perfectly measured the OCS symptoms in Chinese children and adolescents with TD. The results suggested good reliability and validity for the CY-BOCS in patients with TD. The CFA results showed that the two factors structure of CY-BOCS was “stable” in patients with TD. Overall, CY-BOCS showed good psychometric properties in Chinses children with TD.
Some studies demonstrated fine psychometric properties of CY-BOCS in the assessment for the patients with OCD [11, 12]. For instance, the internal consistency was high and had a good interrater agreement for subscale and total OCD [33]. However, few studies investigated the psychometric properties of CY-BOCS in patients with TD. We provide the evidence for the reliability and validity of CY-BOCS, which benefits future studies for the TD with OCS.
TD and OCS are closely related and overlapped in some respects. For example, the altered cortico–striato–thalamo–cortical circuits and dysregulations of the neurotransmitter systems (mainly serotonin and dopamine) are involved in the mechanism of OCS and TD [34–37]. Moreover, the genetic correlation between OCD and TD was higher than between OCD and ADHD [38]. Due to the close relationship between the OCS and TD, assessing OCS in patients with TD is an important issue in future studies [5].
Another aspect to consider is that the total score of Y-BOCS does not represent the severity of symptoms [39], and the total score of CY-BOCS served as an indicator for the severity of OCS may underestimate the degree [40]. For instance, if a child mainly suffers obsessions, the compulsion subscale scores could bring down the total score. Therefore, we should pay attention to both the total score of CY-BOCS and the subscale score. In this present study, we found a confirmed correlation between the obsessions/compulsion subscale and YGTSS and PUTS via the analysis of concurrent validation of CY-BOCS with YGTSS and PUTS. Therefore, we should pay close attention to the factor scores instead of merely the total score of the CY-BOCS applied in TD patients.
In this present study, the Obsessive-Compulsive Scale (OCS) severity was significantly higher in the older group than the younger group. This difference was probably due to the duration of TD in the older group being longer than the younger group. Notably, it was reported that the OCS often appeared at two years after the onset of tic symptoms [41]. Overall, age has an important influence on the severity of OCS in TD patients. Also, few studies provide evidence of the reliability and validity for the CY-BOCS in young children aged less than 8 years [9, 42]. In this study, we found that the CY-BOCS is a reliable and validated scale for assessing the symptom severity in patients with TD aged 5–8 years old. Larger sample studies are warranted to validate the CY-BOCS in the young group.
Several limitations should be clarified in future studies. First, the YGTSS and PUTS were used as the concurrent validity measures, while other scales used to assess obsession and compulsion might be more suitable. Second, the sample only includes the children sample, but not the whole age range, such as the adult sample.