Sensory Phenomenon Assessment Scale (SPAS): a New Tool for Assessment of Tic-associated Sensations

doi:10.21203/rs.3.rs-4024488/v1

Background

Sensory symptoms linked to tic disorder (TD) are challenging to quantify via self-or parent-reported measures. The current study aimed to develop a novel observer-rated semi-structured interview, namely the Sensory Phenomenon Assessment Scale (SPAS), to aid clinical evaluation on symptoms of tic disorder among children.

Methods

To test its psychometric properties, tic, premonitory urge (PU) and obsessive-compulsive symptoms (OCS) were also assessed in 223 children via the Yale Global Tic Severity Scale (YGTSS), Premonitory Urge for Tic Scale (PUTS) and the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS). Factor analysis and internal consistency test were carried out using data from TD-diagnosed individuals.

Results

Good internal consistency and test-retest reliability were observed. Criterion validity was established by significant correlations between the PUTS, the YGTSS, the CY-BOCS, and scores of the SPAS. Factor analyses supported a single-factor model of the SPAS, in which the 5 items each showed a factor loading above 0.6.

Conclusion

This study demonstrated that the SPAS is reliable and valid, thus can serve as a good and concise measure of clinical symptoms among children and adolescents with tic disorder.

Psychiatry

Psychology

Pediatrics

tic disorder

premonitory urge

Sensory Phenomenon Assessment Scale

Reliability and Validity

Tic disorder (TD) is a neurodevelopmental disorder commonly found in children and adolescents(1). Premonitory urge (PU) can occur before, during, or after the onset of tic symptoms. Typical PU symptoms include itchiness, pressure, or a sense of incompleteness(2, 3). Several studies(2, 4) have shown that PU is prevalent in patients with TD, especially those with Tourette syndrome (TS). The sensations are also very salient, as many patients with TS describe the PU as more distressing than the tics themselves(5). Recent behavioral models suggest that PU is the cognition-behavioral basis for tic symptoms. After the onset of the tic symptoms, the individual is relieved from the pain of PU, even if sometimes temporarily(5, 6). Based on cross-sectional data(7, 8), a close positive correlation between severity of PU and tic symptoms in TD individuals should be noticed, which also implies that a higher degree of PU predicts more severe tics. These high correlations of theirs may derive from similar neural mechanisms; for example, both motor tic and PU production are correlated with right insula(9), cingulate cortex volume(10). PU is related to the production, duration, and inhibitory control of tics(11, 12). Fostering awareness and understanding of PU stands as the foundational and pivotal stage in a well-established behavioral intervention for treating TD, Habit Reversal Training (HRT)(13, 14), for example.

Assessing PU objectively holds significance in the examination of TD. Methods devised for evaluating PU encompass both neuropsychological paradigms(11) and assessment scales(15-20). Neuropsychological paradigms were discouraged in clinical evaluation due to their complexity and high demand for equipment. Validated scales for measuring PU include the Premonitory Urges for Tic Disorders Scale (PUTS)(15), its adapted version Premonitory Urges for Tic Disorders Scale-Revised (PUTS-R)(16) and Individualized Premonitory Urge for Tics Scale (I-PUTS)(17), Sensory Processing and Self-Regulation Checklist (SPSRC)(18), Rumination and Awareness Scale for tic-associated sensations (RASTS)(19), and University of Sao Paulo Sensory Phenomena Scale (USP-SPS)(20). Among these tools, PUTS(15) stands out as the most widely used, with translations and validations available in numerous languages(21-23). The majority of clinical studies(4, 24) employed the PUTS to gauge the intensity of PU. PUTS was developed by Professor Woods(15) and first published in 2005. This self-rating scale has a total of 9 items and mainly focuses on the number and frequency of PU. In an earlier study, the reliability and validity of the PUTS(23) have been verified in a Chinese setting by our research team.

However, issues that have not been addressed exist within the current scales. Symptom-related tensity and functional impairment are not fully assessed, while reliability and validity of self-report scales are less solid for children under the age of 10(15, 25). Therefore, a new type of observer-rated scale is in need to provide more accurate and comprehensive assessment.

The current study aimed to develop and validate a new observer-rated semi-structured interview, namely the Sensory Phenomenon Assessment Scale (SPAS). Drawing on the latest research on children's mental health and behavior, we strived to build a tool that accurately reflects the complexity of TD children's PU symptoms and is suitable for clinical practice. We hypothesized that the new instrument would have good reliability and validity and would be suitable for assessing tic related sensory symptoms.

Participants

Participants were recruited from the outpatient clinic of Beijing Children's Hospital from May 1, 2022 to April 30, 2023. Inclusion criteria were: 1) aged 6-17 years; 2) had tic disorder diagnosed by a child psychiatrist according to Diagnostic and Statistical Manual of mental disorders-5 (DSM-5). 3) experiencing premonitory urges (with a total PUTS score exceeding 12). Exclusion criteria were: 1) patients with traumatic brain injury, epilepsy, or intracranial tumors; 2) had comorbid mental disorders.

Informed consent was obtained from each patient and their main caregiver. Procedure of the current study was approved by the Ethics Committee of Beijing Children’s Hospital (approval number: [2023]-E-105-R).

Measures

The Sensory Phenomenon Assessment Scale (SPAS) was developed by the Delphi method. The final version of the SPAS consisted of two parts with 13 items. The first part was the observer-described "symptom list", which contained 8 items (itch, sense of suffocation, pressure, sense of energy release, sense of energy tension, sense of uncompletion, indescribable discomfort, other). The second part is "severity" and contains five items, number, frequency, tensity, degree of transformation and functional impairment. Each item was scored on a six-point scale from 0 to 5, with higher scores indicating severer symptoms. For more details, see Appendix 1 Development of SPAS, Appendix 2 Final version of SPAS and Appendix 3 SPAS User Manual.

The Yale Global Tic Severity Scale (YGTSS) mainly consists of three parts. The first part is a tic inquiry item. In the second part, the number, frequency, intensity, complexity and interference of tics were scored. Each aspect was scored from 0-5, and the maximum total score was 50. The final section is the overall impairment score, with a maximum score of 50. Higher YGTSS score indicates more serious tic symptoms. The reliability and validity of the scale have been verified in the Chinese Taiwan population⁽²⁶⁾. In addition, we had revisited the structure of this scale in a sample of Chinese children with tic disorders⁽²⁷⁾.

Premonitory Urges for Tic Disorders Scale (PUTS) consists of 9 items, each item has 5 scales from 0-4 score scale (a score of 0 = “none”, 1 = ‘‘not at all true,’’ 2 = ‘‘a little true,’’ 3 = ‘‘pretty much true,’’ 4 = ‘‘very much true). Score ranges from 9 to 36. Nine items were used to measure the frequency of sensory symptoms of different nature, the frequency of sensory transformation into tics, and whether sensory phenomena persisted after tics. The reliability and validity of this scale had been validated in Chinese population⁽²³⁾.

The Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS)(28) is a 10-item, clinician-rated, semi-structured scale designed to assess the symptom severity of OCD during a subject’s previous week. Each item is rated by a 5-point Likert scale (0-4). The total score ranges from 0 to 40. CY-BOCS consists of two dimensions: obsessive thoughts and compulsive behaviors. Our team have verified the reliability and validity of this scale in the Chinese population(29).

All patients’ severity of tics were evaluated using SPAS, YGTSS and CY-BOCS by 2 experienced child psychiatrists (Yanlin Li and Xianbin Wang). The Pearson correlation coefficient of consistency was 0.91. All the patients and their parents were then asked to fill in the PUTS.

Statistical Analysis

To verify the reliability of SPAS, we calculated the internal consistency (Cronbach’s a) on all 5 items of part 2 “severity of sensory phenomena”. Because part 1 “symptom list” was not scoring. A split-half reliability analysis was performed on odd and even items and the Spearman-Brown coefficient was computed. Dozens of participants were selected from mild tic patients, who required only clinical observation (no medication or other intervention). and repeated the test one month later to calculate the test-retest reliability.

Validity test included criterion-related validity based on PUTS, YGTSS and CY-BOCS and exploratory factor analysis. Correlation coefficients between the SPAS and the PUTS, YGTSS, as well as the CY-BOCS were calculated respectively. Factor loadings of each item were estimated by exploratory factor analysis.

All these calculation above were performed separately on sample younger than 10 years of age (group 1) and sample of age greater than or equal to 10 (group 2) used IBM SPSS Statistics 19.

Two hundred and twenty-three TD children and adolescents (187 males, 36 females) were enrolled in the testing sample according to inclusion and exclusion criteria. Participants were divided into the group 1 (N=124, aged less than 10 years) and the group 2 (N=99, aged more than or equal to 10 years). Details of demographic information (age and gender) and mean SPAS scores in each group are shown in Table 1.

INSERT Table 1

Reliability of SPAS

Internal consistency

The Cronbach's α coefficients for SPAS were 0.844 for the total sample (n = 223), 0.870 for the group 1 (aged less than 10 years), and 0.801 for the group 2 (aged more than or equal to 10 years). Furthermore, the Spearman-Brown coefficients for these samples were 0.866, 0.901, and 0.813 separately, indicating strong split-half reliability. For more details, see Table 2.

Test-retest reliability

Fifty-three patients were selected and refilled the SPAS one-month later. The correlation coefficient between the two measurements was 0.987 (p < 0.01).

INSERT Table 2

Validity of SPAS

Criterion-related validity

The total SPAS scores of the total, younger and older groups were significantly positively correlated with scores of the PUTS (p < 0.01), but not with the YGTSS (p > 0.05) or the CY-BOCS (p > 0.05). Each correlation coefficient had been shown in Table 3.

Validity of construct

The score of each item of the SPAS was not only significantly correlated with the total score, but each had a factor loading greater than 0.5. For more details, see Table 3.

INSERT Table 3

The present study reports the development and validation of the SPAS, a new tool to quantitatively measure individual differences in tic-related sensory phenomena. Concur with our hypotheses, the SPAS demonstrated good psychometric properties.

The final version of the SPAS was developed through literature search, and Delphi expert consultation. The overall framework of the SPAS appeared to be reasonable for assessing sensory symptoms associated with TD in children and adolescents. Some reasons supporting the reasonableness of the framework were as followed.

On the one hand, the SPAS has been designed to be an observer-rated scale. Previous scales(15, 18, 19) used to assess PU or sensory symptoms were all self-reported, with the exception of I-PUTS(17). The SPAS and I-PUTS were clinician-rated scale, which might avoid the interference of subjectivity from patients. A meta-analysis(30) indicated that clinician-rated instruments resulted commonly enjoy significantly higher effect sizes than their self-reported counterparts. Though another study(31) stated that both self-report scales and clinician-rated scales were irreplaceable and complement to each other.

On the other hand, the two-part structure of SPAS, with a symptom list and a severity assessment, was a well-thought-out design. The symptom list captured the variety of sensory phenomena associated with tic disorders, while the severity assessment quantified the intensity and impact of these symptoms on the child's daily life. The severity assessment part of the SPAS included items such as number, frequency, tensity, degree of transformation, and functional impairment. Given that I-PUTS evaluated PU only by three dimensions (number, frequency, and intensity), the SPAS may serve as a more comprehensive tool for assessing PU in tic disorder.

The SPAS demonstrated satisfactory performance in terms of these reliability and validity. The one-month test-retest reliability assessment of SPAS revealed highly significant correlations (p < 0.01), with a correlation coefficient of 0.987. Our findings affirm the stability and reliability of the measurement instrument, meeting the prescribed criteria for reliability. Strong reliability for both the younger population, under 10 years of age, and the older group comprising children and adolescents aged 10 years and above. Furthermore, this observation compensates for the less than satisfactory reliability exhibited by the previous tool PUTS when applied to TS patients under the age of 10(32). Evidence suggested that the incidence of PU in TD patients increases with age(33). The reason for this may involve a growing physiological awareness (or body-awareness) with age. This also made older children more aware of the presence of PU. Other studies have suggested that this body awareness was negatively related to inhibitory function(34), and PU seemed to be related to inhibitory function(35), so we hypothesized that the incidence of PU increases with age, possibly because of increased body awareness. This also made it difficult for younger children (especially under the age of 10) to understand the meaning of the items when they complete the self-rating questionnaire (because they may never be aware of the intuitive feeling).

Subsequently, the validity analysis had factor loadings greater than 0.5 after exploratory factor analysis, indicating that these items together contribute to one dimension – the severity of PU. The unidimensional scale has demonstrated benefits in clinical settings due to its simplicity for clinical assessors, straightforward administration, and the ease with which results can be shared for clinical reference.

We then selected PUTS, YGTSS, and CY-BOCS as criteria for calculating criterion validity. The total score of SPAS exhibited a significant positive correlation with the total score of PUTS (p < 0.001). However, there was no observed correlation between the total score of SPAS and the total score of YGTSS and CY-BOCS. These findings suggest that SPAS demonstrates robust criterion validity, primarily assessing the severity of PU (as indicated by its lack of correlation with YGTSS and CY-BOCS total score), rather than other measures such as tic symptoms and obsessive-compulsive symptoms. However, in most prior investigations of the PUTS(15), PUTS-R(16), and I-PUTS(17), a least moderate significant correlation with the YGTSS was presented. The reason for our inconsistency with previous results may be that our sample was only TD patients aged 6-16 years with PU. A larger sample size and more age-stratified TD patients (such as young adults) may be needed in the future to explore the correlation between the results of SPAS scale and other scales.

Our study bears several limitations. Firstly, for convenient access, our sample comprised of children and adolescents exclusively. Future investigations should include adults with TD for gaining comprehensive insight. Secondly, while we employed the YGTSS, the PUTS, and the CY-BOCS as concurrent validity measures, alternative scales such as the University of São Paulo Sensory Phenomena Scale (USP-SPS)(20), specifically designed for PU assessment, might offer alternative result. Lastly, this study did not establish a cut-off value, which may impede the practical use of SPAS. Future research might benefit from addressing this issue and exploring potential cut-off values for clinical application.

Following psychometric testing, the newly-developed scale SPAS demonstrated robust reliability and validity, fulfilling the prerequisites for clinical scales. Subsequent clinical applications confirmed the utility of this scale, indicating its capacity to provide a comprehensive evaluation of PU severity in TD children and adolescents aged 6–17 years.

Acknowledgment We thank all the participants for their support in this study.

Author Roles

1.Research project: A. Conception, B. Organization, C. Execution;

2.Statistical Analysis: A. Design, B. Execution, C. Review and Critique;

3.Manuscript Preparation: A. Writing of the first draft, B. Review and Critique;

Xianbin Wang: 2ABC and 3B

Yanlin li: 2BC and 3A

Yonghua Cui and Ying Li: 1ABC

Other authors: 3B

Disclosures

Funding Sources and Conflict of Interest:

This work was supported by the National Natural Science Foundation of China (NSFC) under Grant No. 8217051233, 82171538, 82001445 and the Natural Science Foundation of Beijing Municipality under Grant No. 7212035, Beijing Hospitals Authority Youth Programme Grant No. QML202112031. The authors declare that there are no conflicts of interest relevant to this work.

Financial Disclosures for the previous 12 months:

The authors declare that there are no additional disclosures to report.

Ethical Compliance Statement We obtained the informed consent of all patients and obtained the ethical approval issued by the Ethics Committee of Beijing Children’s Hospital.

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Table 1 The clinical characteristics for different groups

Groups	n	Male/Female	Mean age (SD)	SPAS Mean (SD)
Younger group	124	99/25	7.7 (1.203)	8.99 (6.013)
Older group	99	88/11	11.92 (1.957)	8.87 (5.108)
p	-	0.068	-	0.977

SPAS, Sensory Phenomenon Assessment Scale; SD, Standard Deviation; N/A, Not Available; Younger Group: age < 10; Older Group: age ≥ 10

*comparison between age group; ** comparison between PU group

Table 2 Reliability of SPAS

	Younger group (n = 124)	Older group (n = 99)	Total (n = 223)
Cronbach’s Alpha	0.870	0.801	0.844
Spearman-Brown	0.901	0.813	0.866

SPAS, Sensory Phenomenon Assessment Scale; Younger Group: age < 10; Older Group: age ≥ 10

Table 3 Validity of SPAS

	Younger group (n = 124)	Older group (n = 99)	Total (n = 223)
Criterion-related validity
PUTS and SPAS	0.578*	0.389*	0.494*
YGTSS and SPAS	-0.050	0.030	-0.027
CY-BOCS and SPAS	-0.047	0.136	0.060
Bartlett's test of sphericity	309.019*	160.231*	464.436*
Factor loading for exploratory factor analysis**
Item 9	0.831	0.724	0.790
Item 10	0.851	0.832	0.844
Item 11	0.846	0.761	0.814
Item 12	0.838	0.801	0.820
Item 13	0.720	0.608	0.662

PUTS, Premonitory Urge to Tic Scale; SPAS, Sensory Phenomenon Assessment Scale; YGTSS, Yale Global Tic Severity Scale; CY-BOCS, Children’s Yale-Brown Obsessive-Compulsive Scale; *p < 0.01; **Only one factor was analyzed by exploratory factor analysis for each sample, and the variance contribution for all of 3 sample rates were 67.024%, 56.162% and 62.242%;

The authors declare no competing interests.

Sensory Phenomenon Assessment Scale (SPAS): a New Tool for Assessment of Tic-associated Sensations

Status:

Version 1

Abstract

Introduction

Methods

Participants

Measures

Statistical Analysis

Results

Discussion

Conclusion

Declarations

References

Tables

Additional Declarations

Supplementary Files

Status:

Version 1