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ScienceDirect Comprehensive Psychiatry 61 (2015) 122 – 130 www.elsevier.com/locate/comppsych

Reliability and validity of the Korean version of the Scale for the Assessment of Thought, Language, and Communication Seon-Cheol Park a, b , Eun Young Jang c , Kang Uk Lee d , Kounseok Lee e , Hwa-Young Lee f , Joonho Choi b, c,⁎ a

Department of Psychiatry, Yong-In Mental Hospital, Yongin, Republic of Korea b Institute of Mental Health, Hanyang University, Seoul, Republic of Korea c Department of Psychiatry, Hanyang University Guri Hospital, Guri, Republic of Korea d Department of Psychiatry, Kangwon University School of Medicine, Chuncheon, Republic of Korea e Department of Psychiatry, St. Andrew's Neuropsychiatric Hospital, Icheon, Republic of Korea f Department of Psychiatry, Soonchunhyang University Cheonan Hospital, Cheonan, Republic of Korea

Abstract Background: Our study aimed to assess the inter-rater and test-retest reliability, as well as concurrent and convergent validity, of the Korean version of the Scale for the Assessment of Thought, Language, and Communication (TLC scale). Methods: The factor solutions and psychometric properties of the Korean version of the TLC scale were evaluated among 167 schizophrenia inpatients (study subjects) at two sites in South Korea. Using Pearson’s correlation, the concurrent and convergent validities of each of the factor solutions were represented by the correlations with the scores on the Clinical Language Disorder Rating Scale, Brief Psychiatric Rating Scale, Young Mania Rating Scale, and Calgary Depression Scale. Using receiver operating characteristics curves, the optimal cut-off score for the Korean version of the TLC scale to distinguish between study subjects with and without disorganized speech, was identified. Results: The results showed that the Korean version of the TLC scale has a three-factor solution: fluent disorganization, speech emptiness, and speech peculiarity. In addition, the interrater reliability of the Korean version of the TLC scale was moderately good (intraclass correlation coefficient = 0.51) and its test-retest reliability was very good (Pearson’s correlation coefficient = 0.94). For detecting the current presence of disorganized speech, the optimal cut-off total score on the TLC scale was proposed to be 8 points (sensitivity = 88.1%; specificity = 82.9%). Limitations: Psychometric tools covering cognitive functions were not used in our study. Conclusions: The Korean version of the TLC scale is a promising psychometric method for examining formal thought disorder (FTD) and disorganized speech in schizophrenia patients. © 2015 Elsevier Inc. All rights reserved.

1. Introduction Formal thought disorder (FTD) has been regarded as the hallmark diagnostic syndrome of schizophrenia. According to a systematic review, the prevalence of FTD ranges from 5% to 91%, and FTD could be regarded as a marker of the clinical severity of psychosis [1]. In the early stage of modern psychopathology, Wilhelm Griesinger [2] proposed the concept of ‘Inkohärenz’ (corresponding to incoherence), which indicated the external ⁎ Corresponding author at: Department of Psychiatry, Hanyang University Guri Hospital, Gyeongchun-ro 148beon-gil, Guri 471-701, Korea. Tel.: +82 31 560 2273; fax: +82 31 554 2599. E-mail address: [email protected] (J. Choi). http://dx.doi.org/10.1016/j.comppsych.2015.04.002 0010-440X/© 2015 Elsevier Inc. All rights reserved.

similarity of sound in word productions. Emil Kraepelin [3] regarded ‘Zerfahrenheit’ (corresponding to derailment), which referred to the loss of internal or external connection between the chains of ideas in schizophrenia, as the typical form of thought and language disorder in schizophrenia. Similarly, Eugen Bleuler [4] considered that the ‘loosening of associations’, namely, the absence of association-continuity, was the most important symptom of schizophrenia. As a result of these ideas, Bleuler [5] renamed dementia praecox as schizophrenia. However, in the Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM-III) [6], FTD, in the diagnostic criteria for schizophrenia, was defined as a hybrid of the independently originated concepts of incoherence (from Griesinger) and loosening of associations (from Bleuler). In the Diagnostic and Statistical Manual of Mental Disorders, Fourth

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Edition (DSM-IV) [7], a strengthening trend towards a neo-Kraepelinian approach altered the expression ‘incoherence or loosening of associations’ to ‘disorganized speech’. Finally, in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) [8], disorganized speech was included and measured as one domain of the Clinician-Rated Dimensions of Psychosis Symptom Severity (CRDPSS) [9]. Thus, FTD has developed over time from its initial concept as a thought disorder into a speech disorder, with the latter now generally recognized as the reciprocal or equivalent of the former in the psychopathology of schizophrenia. Several psychometric assessment scales for FTD have been introduced into clinical research on schizophrenia. Most of these focus mainly on objective symptoms that can be simply quantified, even though Parnas et al. [10,11] have emphasized the importance of the patient’s own perspective on the world and self for understanding the FTD of schizophrenia patients. Recently, the Thought and Language Disorder (TALD) scale has been developed to assess subjective as well as objective FTD, and its reliability has been validated [12]. The Scale for the Assessment of Thought, Language, and Communication (TLC scale) defined operationally the idea that FTD is a clinical syndrome with heterogeneous features rather than a single, shared, and essential symptom among the manifestations of schizophrenia. The TLC scale was developed to evaluate thought and language symptoms in schizophrenia, on the grounds that external language use can be more reliably measured than internal self-experience. The scale was validated in the differential diagnosis of patients with schizophrenia and bipolar disorder [13–16]. The TLC scale was used subsequently to assess the clinical manifestations of FTD in patients, in clinical studies of schizophrenia [17–21]. Using the TLC scale, several neuroimaging studies have suggested that morphological and functional alterations of the left superior temporal sulcus and adjacent structures are implicated in the presence of FTD in schizophrenia [22–24]. In addition, using the TLC scale, studies have found that FTD and alogia can be differentiated in terms of the cognitive mechanisms indicated by the patterns of verbal fluency [25]. Despite the usefulness and availability of the TLC scale globally, to our knowledge, standardization studies have been extremely rare and no translation into Korean has been made. Hence, for patients with diagnosed schizophrenia, we aimed to: (i) extract the factor structure and essential characteristics of the TLC scale in terms of individual dimensions, (ii) analyze the interrater and test-retest reliability and the concurrent and convergent validity of the Korean version of the TLC scale, and (iii) identify the cut-off value for defining presence of disorganized speech. 2. Material and methods 2.1. Study subjects and procedures From January 2014 to June 2014, study subjects were enrolled from 167 inpatients with schizophrenia in Yong-In

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Mental Hospital and National Chuncheon Hospital, in South Korea. Our inclusion criteria were as follows: (i) diagnosis of schizophrenia with DSM-V (American Psychiatric Association, 2013), (ii) age ≥18 years and ≤65 years, and (iii) length of hospital stay ≥2 weeks. In addition, our exclusion criteria were: (i) presence of organic mental disorder, intellectual disability, or alcohol or other substance use disorders, (ii) presence of seizure disorder or other neurological diseases, (iii) presence of severe medical or surgical disease, (iv) educational level less than elementary school, and (v) insufficient fluency in Korean: fluency in spoken Korean was assessed based on the individual sections of the Test of Proficiency in Korean, evaluated by estimating overall ability in pronunciation, grammar, vocabulary, discourse, socio-linguistics, and interaction; hence, insufficient Korean fluency was operationally defined as less than primary grade ability in spoken Korean. The study protocol was approved by the Institutional Review Board of Yong-In Mental Hospital (receipt number: 2013–49). All study subjects gave informed consent before the study. Before starting the study, a one-day training workshop was held for 6 independent raters, including 2 psychiatrists (SCP, CJ) and 4 psychiatric residents (HJY, SMH, BK, JMY). The training workshop program included manual review, ratings of audiotape-recorded TLC scale interviews, and discussion. Four (SCP, CJ, BK, JMY) of the 6 independent raters, chosen at random, independently rated audiotape-recorded interviews for the Korean version of the TLC scale. Interrater reliability was assessed from the results of the four independent raters. The detailed interview procedures were as follows: each of the independent raters dealt with all the scales for symptom measurement; and the average time taken to carry out the interview was about 80 minutes. The interviews were not recorded by audiotape or videotape, but we continually discussed and reached consensus on the evaluation of arbitrary ratings. To elicit a speech sample under standardized conditions, we used some of the methods suggested in the Clinical Language Disorder Rating Scale (CLANG) [26] as follows: (i) spontaneous speech on neutral topics, (ii) responses to an open question, or (iii) retelling of a short story of neutral content. The TLC scale [13–16], CLANG [26], Brief Psychiatric Rating Scale (BPRS) [27], Young Mania Rating Scale (YMRS) [28], Calgary Depression Scale for Schizophrenia (CDSS) [29], and the disorganized speech domain of CRDPSS [9] were administered in a fixed order. After 3 to 4 weeks, the Korean version of the TLC scale was evaluated in a non-random sample of 148 patients among the existing study subjects to assess test-retest reliability. 2.2. The TLC scale and its forward and backward translations According to the original definitions of Andreasen [15], half of the 18 items of the TLC scale, (poverty of speech, poverty of content of speech, pressure of speech, distractible speech, tangentiality, derailment, incoherence, illogicality,

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and clanging) were rated from 0 (absent) to 4 (extreme); the other half (neologisms, word approximations, circumstantiality, loss of goal, preservation, echolalia, blocking, stilled speech, and self-reference) were rated from 0 (absent) to 3 (severe). Using the TLC scale, more persistent patterns of FTD and abnormality in language behavior were demonstrated in patients with schizophrenia than in those with mania [16]. The translation process for the Korean version of the TLC scale proceeded as follows: we obtained permission from Dr. Nancy C. Andreasen to translate the TLC scale and use it in a psychometric validation study. Forward and backward translations were performed in accordance with the guidelines for developing other language versions of the questionnaire [30], except for a pre-test. Two independent forward translations were made by two independent psychiatrists (SCP, KL) who were excellent in Englishto-Korean translation. A consensus version was then made by discussion between the two psychiatrists, and backwards translated by a professional translator who majored in clinical psychology (JJ). After careful matching of the backwards translation with the original version and some modifications, the final Korean version of the TLC scale was approved. Only the Korean version of the TLC scale was used in this study. 2.3. Psychometric assessments Psychometric scales including the CLANG [26], BPRS [27], YMRS [28], CDSS [29], and the disorganized speech domain of the CRDPSS [9] were used to analyze the concurrent and convergent validity of the Korean version of the TLC scale, and evaluate, respectively, clinical language disorder, overall psychiatric symptoms, manic symptoms, depressive symptoms, and presence of disorganized speech. In the 17-item CLANG, five factors, namely syntactic, semantic, production, pressure, and prosody were extracted [26]. The BPRS, YMRS, and CDSS had been formally translated into Korean and confirmed as reliable and valid in Korean populations [31–33]. The psychometric properties of the Korean version of the CLANG had not been evaluated, but, in our study, its Cronbach α coefficient for 17 items was 0.81 and considered good (0.7 ≤ α b 0.9). We used the English version of the disorganized speech domain of the CRDPSS in our study. Since the BPRS covered diverse symptom domains in addition to the positive and negative symptom domains, we used the BPRS for symptom measurements in preference to the Scale for the Assessment of Positive Symptoms (SAPS) [34] and the Scale for the Assessment of Negative Symptoms (SANS) [35]. Each of four subscales was defined as follows: The positive symptom subscale consisted of the conceptual disorganization, suspiciousness, hallucinatory behavior, unusual thought content, and disorientation items; The negative symptom subscale consisted of the emotional withdrawal, motor retardation, and blunted affect items; The psychological

discomfort subscale consisted of the somatic concern, anxiety, guilt feelings, tension and depressive mood items; and the resistance subscale consisted of the grandiosity, hostility, uncooperativeness, and excitement items [36]. For the 17-item CLANG and CDSS, all items were rated from 0 (normal) to 3 (severe). In the 18-item BPRS, all items were rated from 1 (absence of symptoms) to 7 (extremely severe). For the 11-item YMRS, 7 items were rated from 0 (normal) to 4 (severe), and 4 items, namely, irritability, speech, content, and disruptive-aggressive behaviors were rated from 0 (normal) to 8 (severe). In addition, since the disorganized speech domain of the CRDPSS was rated from 0 (not present) to 4 (severe), the presence of disorganized speech was operationally defined by the condition that the domain score was 2 or more (corresponding to definitely present).

2.4. Statistical analysis Means were calculated for all items of the 18-item TLC scale. An exploratory factor analysis (EFA) was performed on the TLC scale, with maximum likelihood extraction by the direct oblimin method. The number of factors retained for rotation was based on a scree plot, in addition to eigenvalues and expandability [37]. To clearly demonstrate the factor structure and contents, only a loading of more than 0.40 was considered. In addition, Cronbach’s α coefficients were used to assess the internal consistency of factors composed of several items. Pearson’s correlation coefficients were also calculated to examine the associations between factors. To obtain concurrent validity, we calculated Pearson’s correlation coefficients between factors of the TLC scale and factors of the CLANG. Pearson’s correlation coefficients were also calculated to examine the associations between factors of the TLC scale and scores on the positive and negative subscales of BPRS, YMRS, and CDSS. The intraclass correlation coefficient (ICC) was used to evaluate interrater reliability for the four independent raters, and Pearson’s correlation coefficient was used to assess test-retest reliability. Significance was set at P b 0.05 (two-tailed) for all tests. Receiver operating characteristic (ROC) curve analysis was used to identify the optimal cut-off score which detected accurately presence of disorganized speech in patients with schizophrenia. This statistical method was developed from signal-detection theory, and is frequently used in biological and behavioral studies [38] and has been described in more detail elsewhere [39]. In calculating overall predictor performance, we considered the sensitivity/specificity pairs for all possible threshold levels to determine the cut-offs generating the lowest number of false positives and false negatives. All statistical analyses were performed using SPSS 18.0 for Windows (SPSS, Chicago, IL, USA).

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3. Results 3.1. Study subjects and descriptive characteristics The study subjects were largely characterized as chronically ill, unmarried, and under-educated (Table 1). Scores on the CLANG, BPRS, YMRS, and CDSS ranged from moderate to low. The mean chlorpromazine-equivalent dose (mg) for the subjects was 921.1. The scores on items for TLC scale are presented in Table 2. The average scores on three (16.7%) items, namely poverty of content of speech, tangentiality, and derailment, exceeded one point. The average scores on 15 (83.2%) items were less than one point. The distributions of all items were evaluated by Bulmer’s criteria [40] and 11 (61.1%) items were strongly positively skewed (N +1), indicating that the majority were rated 0. In addition, seven (38.9%) items were moderately positively skewed (between 0.05 and 1), indicating the majority had relatively low scores. None of the scale items were approximately symmetric and normally distributed. Our mean items scores are compared with the findings of previous studies, which mean item scores were given, in Table 2. 3.2. EFA This study’s sample size was above the minimum recommended for EFA (n N 150) [41]. The correlation Table 1 Baseline characteristics of study subjects (n = 167). Mean (SD) or n (%) Age (years) Gender Men Women Marital status Married Unmarried Educational attainment Below high school graduate Above college graduate Religion Affiliated Unaffiliated Hospital A B Age at onset (years) † Chlorpromazine-equivalent (mg) Clinical Language Disorder Rating Scale Syntactic Semantic Production Pressure Prosody Brief Psychiatric Rating Scale Positive symptom Negative symptom Young Mania Rating Scale Calgary Depression Scale for Schizophrenia †

n =131.

46.5 (11.2) 86 (51.5) 81 (48.5) 38 (20.9) 129 (79.1) 108 (73.0) 59 (27.0) 99 (61.5) 68 (38.5) 145 (86.8) 22 (13.2) 25.2 (7.0) 921.1 (952.0) 8.3 (6.9) 1.3 (1.9) 2.3 (2.7) 2.5 (2.5) 0.8 (1.0) 1.4 (1.6) 40.1 (12.3) 13.5 (5.8) 8.9 (3.9) 7.3 (6.9) 1.5 (2.5)

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matrix showed that many coefficients were greater than 0.40, and Bartlett’s test for sphericity was significant (χ 2 (167) = 317.76, P b 0.001). All the indicators suggested that the data were suitable for EFA, and all the items were included in the EFA. Since there was a distinct change in the slope of the eigenvalues after the third component of the scree plot, we extracted a three-factor solution (Fig. 1). The factor loadings for the three-factor solution were presented in Table 3. The first factor consisted of the items for loss of goal, derailment, tangentiality, incoherence, illogicality, circumstiantiality, clanging, distracted speech, word approximations, neologisms, and echolalia, and was named “fluent disorganization.” Although the factor loading of the echolalia item was less than 0.40, because of its conceptual similarity to fluent disorganization it was aggregated with the latter. The second factor consisted of the items for poverty of speech, poverty of content of speech, blocking, and pressure of speech (negative weight), and was named “speech emptiness.” The third factor consisting of the items for self-reference, preservation, and stilted speech, was named “speech peculiarity.” Correlation coefficients for the three factors ranged from 0.342 to 0.465 (fluent disorganization and speech emptiness, r = 0.407, P b 0.0001; fluent disorganization and speech peculiarity, r = 0.342, P b 0.0001; speech and emptiness and speech peculiarity, r = 0.465, P b 0.0001). Cronbach’s α for the 18-item TLC scale was 0.87 and its reliability was considered good (0.7 ≤ α b 0.9). In addition, α values for the three factors ranged from 0.64 to 0.88 and were considered acceptable (0.6 ≤ α b 0.7) or good (Table 3). 3.3. Interrater and test-retest reliability The interrater reliability of the four independent raters for the Korean TLC scale was calculated as 0.51 (F = 3.209, P b 0.0001) by ICC and considered moderate. In addition, test-retest reliability was considered high (r = 0.941, P b 0.0001). 3.4. Concurrent and convergent validity As shown in Table 4, except for the correlation coefficient for fluent disorganization and production (CLANG) (r = 0.150, P = 0.054), the correlation coefficients between the TLC scale and CLANG factors ranged from 0.23 to 0.77 and were significant (P b 0.0001). As shown in Table 5, the fluent disorganization factor was significantly correlated with the positive symptom (r = 0.749, P b 0.0001), negative symptom (r = 0.294, P b 0.0001), psychological discomfort (r = 0.172, P = 0.026) and resistance (r = 0.454, P b 0.0001) subscales of BPRS and YMRS (r = 0.447, P b 0.0001), whereas it was not significantly correlated with the CDSS (r = −0.152, P = 0.051). The speech emptiness factor was significantly correlated with the positive symptom (r = 0.431, P b 0.0001), negative symptom (r = 0.625, P b 0.0001) and resistance (r = 0.232, P = 0.003) subscales of BPRS, YMRS (r = 0.205, P = 0.008) and CDSS (r = −0.164, P = 0.034), whereas it was not significantly correlated with the

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Table 2 Mean item scores on the TLC scale. Item

Present study (n = 167)

Andreasen, 1979a (n = 45)

Peralta et al., 1992 (n = 115)

Bazin et al., 2002 (n = 107)

Andreou et al., 2008 (n =103)

Salavera et al., 2013 (n = 102)

1. Poverty of speech 2. Poverty of content of speech 3. Pressure of speech 4. Distractible speech 5. Tangentiality 6. Derailment 7. Incoherence 8. Illogicality 9. Clanging 10. Neologisms 11. Word approximations 12. Circumstantiality 13. Loss of goal 14. Perservation 15. Echolalia 16. Blocking 17. Stilted speech 18. Self-reference

0.86 1.17 0.40 0.52 1.02 1.09 0.68 0.99 0.17 0.13 0.25 0.77 0.98 0.44 0.01 0.46 0.50 0.62

0.47 0.76 0.36 0.02 0.55 0.12 0.33 0.45 0.00 0.02 0.00 0.01 0.71 0.13 0.07 0.06 0.02 0.16

1.00 1.41 0.32 0.77 1.09 1.09 0.89 1.54 0.13 0.07 0.30 0.69 1.03 0.98 0.12 0.57 0.17 0.16

1.35 1.91 0.77 0.92 1.79 1.62 0.59 1.38 0.26 0.36 0.75 0.88 1.63 0.98 0.16 0.50 0.32 0.94

0.67 1.34 0.34 0.17 0.58 0.57 0.29 0.09 0.01 0.07 0.20 0.34 0.48 1.02 0.01 0.09 0.12 0.48

2.09 0.81 0.46 0.63 0.90 0.52 0.11 0.40 0.62 0.34 0.88 0.72 0.85 0.63 0.11 0.03 0.50 0.74

TLC scale, Scale for the Assessment of Thought, Language and Communication.

psychological discomfort subscale (r = −0.036, P = 0.641) of BPRS. The speech peculiarity factor was significantly correlated with the positive symptom (r = 0.196, P = 0.011) and negative symptom (r = 0.167, P = 0.031) subscales of BPRS, whereas it was not significantly correlated with the psychological discomfort (r = 0.033, P = 0.667) and resistance (r = 0.115, P = 0.139) subscales of BPRS, YMRS (r = −0.067, P = 0.387) and CDSS (r = −0.079, P = 0.311). 3.5. ROC curve analysis In a ROC curve analysis (Fig. 2), the TLC scale was found to accurately distinguish between schizophrenia patients with and without disorganized speech (area under the curve

[AUC] = 0.929, P b 0.0001). Using the optimal cut-off score of 8 points, the sensitivity and specificity of the total score on the TLC scale were 88.1% and 82.9%, respectively.

4. Discussion As can be seen from Table 2, the severity of most items of the Korean version of the TLC scale was similar to previous study findings [13,17,18,20,21]. In our study, the score on the stilted speech item was high compared with previous studies. This may be a function of the population used in the survey, as a relatively high proportion of chronically ill patients were enrolled in our study.

Fig. 1. Scree plot for factor eigenvalues of the Korean version of the TLC scale.

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Table 3 The three-factor solution of the Korean version of the TLC scale and internal consistency of the factors. Factor

Item

Loading

Eigenvalue

% variance

Cronbach α

Fluent disorganization

13. Loss of goal 6. Derailment 5. Tangentiality 7. Incoherence 8. Illogicality 12. Circumstantiality 9. Clanging 4. Distractible speech 11. Word approximations 10. Neologisms 15. Echolalia 1. Poverty of speech 2. Poverty of content of speech 16. Blocking 3. Pressure of speech (negative weight) 18. Self-reference 14. Preservation 17. Stilted speech

0.90 0.90 0.86 0.80 0.64 0.56 0.53 0.51 0.46 0.46 0.16 0.76 0.62 0.59 −0.52 0.69 0.63 0.54

5.63

31.28

0.88

2.09

11.59

0.69

1.03

5.71

0.64

Speech emptiness

Speech peculiarity

TLC, Scale for the Assessment of Thought, Language and Communication.

Our study yielded a three factor solution for the Korean version of the TLC scale in. Previous factor solutions of the TLC were somewhat variable, and three or more factor solutions have been extracted from several language versions of the TLC scale for schizophrenia patients [17,18,20]. Our findings are consistent with those of Nagel et al. [42] who extracted a three factor solution reflecting disorganization, emptiness, and linguistic control factors for the German version of the TLC scale using 146 patients with diagnoses of schizophrenia, mania, and depression. The previously yielded factor structures for the various language versions of the TLC scale were as follows: for the English version, a five-factor structure reflecting disorganization, negative, stilted speech/word approximations, neologisms/clanging, and distractibility/blocking [20]; for the French version, a five-factor structure reflecting thinking disorganization, verbal production, verbal structure, stilted speech, and distractible speech/blocking factors [18]; for the Greek version, a three-factor structure reflecting disorganization of speech, peculiarities of speech, and verbosity factors [17]. The subtle variations of factor structure in our and previous studies could be due to differences in inclusion criteria and the clinical characteristics of the study subjects. These

variations might also be due to differences in statistical procedures including eigenvalues and visual inspection of scree plot. Despite this variation, the fluent disorganization, speech emptiness, and speech peculiarity factors for the Korean version of the TLC scale are comparable to those reported in previous and/or other language version studies. Since, as Andreou et al. suggested [17], a simple factor structure can be more reliable in terms of clinical practice, stilted speech is regarded not as a factor consisting of one item but as one of the elements of fluent disorganization. In addition, all the internal consistency values for the three factor solution were considered acceptable or good. The concurrent validity of the Korean version of the TLC scale is demonstrated by the significant correlation between its three factors and the CLANG subscales. These findings are partly consistent with Chen et al.’s findings [26] that the semantics subscale of the CLANG is significantly correlated with total score on the TLC scale (r = 0.344, P b 0.00001) and substantial items of the CLANG are also significantly correlated with derailment, incoherence, clanging, poverty of speech, increased latency items of the TLC scale. In addition, the convergent validity of the Korean version of the TLC scale is supported by the significant correlation

Table 4 Correlations between the Korean version of the TLC scale and CLANG factors.

Syntactic (CLANG) Semantic (CLANG) Production (CLANG) Pressure (CLANG) Prosody (CLANG)

Fluent disorganization (TLC scale)

Speech emptiness (TLC scale)

Speech peculiarity (TLC scale)

0.77⁎⁎ 0.86⁎⁎ 0.15 0.34⁎⁎ 0.61⁎⁎

0.29⁎⁎ 0.47⁎⁎ 0.80⁎⁎ 0.23⁎⁎ 0.35⁎⁎

0.33⁎⁎ 0.36⁎⁎ 0.34⁎⁎ 0.37⁎⁎ 0.26⁎⁎

*P b 0.05. CLANG, Clinical Language Disorder Rating Scale; TLC scale, Scale for the Assessment of Thought, Language and Communication. ⁎⁎ P b 0.01.

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Table 5 Correlations between the Korean version of the TLC subscales and other psychometric assessments.

Positive symptom (BPRS) Negative symptom (BPRS) Psychological discomfort (BPRS) Resistance (BPRS) YMRS CDSS

Fluent disorganization (TLC scale)

Speech emptiness (TLC scale)

Speech Peculiarity (TLC scale)

0.75⁎⁎ 0.30⁎⁎ 0.17⁎ 0.45⁎⁎ 0.45⁎⁎ −0.15

0.43⁎⁎ 0.63⁎⁎ −0.36 0.23⁎⁎ 0.21⁎⁎ −0.16⁎

0.20⁎ 0.17⁎ 0.33 0.12 −0.07 −0.08

CDSS, Calgary Depression Scale for Schizophrenia; CLANG, Clinical Language Disorder Rating Scale; TLC scale, Scale for the Assessment of Thought, Language and Communication; YMRS, Young Mania Rating Scale. ⁎ P b 0.05. ⁎⁎ P b 0.01.

between its three factors and the positive and negative subscales of BPRS, YMRS, and CDSS. Remarkably, the speech peculiarity factor is significantly correlated not with manic and depressive features but with positive and negative psychotic symptoms, whereas the fluent disorganization factor is correlated with manic features, while psychotic symptoms and the speech emptiness factor are significantly correlated with psychotic, manic, and depressive symptoms. Peralta et al. [20] reported that the disorganization factor is correlated with the severity of formal thought disturbance, and the negative factor is correlated with poor premorbid functioning and poor response to antipsychotic treatment. Hence, our findings suggest that the fluent disorganization, speech emptiness, and speech peculiarity factors have distinctive features, in terms of their correlations with psychotic, manic, and depressive symptoms, respectively. To our knowledge, our study is the first to demonstrate interrater and test-retest reliability and to provide a cut-off total score for detecting the presence of FTD or disorganized speech for the TLC scale. Interrater reliability was considered to be at a moderate level, since the variability may be caused by a fact that we have not established a standard score for each of the items of the Korean version of

the TLC scale. Remarkably, test-retest reliability appears to be high. Hence, our findings indicate that the Korean version of the TLC scale is stable for 3 to 4 weeks. With a cut-off score of 8 points, it accurately discriminates between schizophrenia patients with and without disorganized speech, with a sensitivity of 88.1% and a specificity of 82.9%. The selected cut-off score for the Korean version of the TLC scale suggests that extreme levels in even two items or moderate or severe levels in three or more items point to the presence of FTD or disorganized speech in schizophrenia patients. Kircher et al. [12] have proposed that the TLC scale has several potential problems including idiosyncratic definitions of several items, lack of coding of subjective experiences, and different maximal severities of the items (4 points for some items and 3 points for others). Hence, as mentioned earlier, the TALD scale has a 4 factor solution including objective positive, subjective positive, objective negative, and subjective negative domains, and it has been proposed as an alternative clinical tool covering the comprehensive domains of FTD. There are several limitations to our study. First, the enrolled study subjects were confined inpatients (hospitalized) with chronic schizophrenia. Thus, our findings cannot be

Fig. 2. Receiver operating characteristic curve for total scores on the TLC scale in schizophrenia patients with and without disorganized speech.

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extrapolated to other patient populations, particularly those with less severe acute schizophrenia or early psychosis. Secondly, as Docherty et al.’s findings [25] illustrate, FTD or disorganized speech can be influenced by cognitive mechanisms, and we have not used psychometric methods covering cognitive functions. Thirdly, the definition for what constitutes a phrase or clause is less clear in the Korean language than in English. Korean translation and anchor scoring of the TLC scale was not supervised by a linguist in our study. Fourthly, the psychometric properties of the Korean versions of the CLANG and the disorganized speech domain of the CRDPSS were not described in our study, since studies of their standardization have not been presented. Lastly, we evaluated the test-retest reliability of the Korean version of the TLC scale using an interval of 3 to 4 weeks. Although we could not exclude the possibility that the symptoms might actually change over that time, considering the chronically affected states of the study subjects (mean duration of illness; 21.3 years), such changes should be minimal. In addition, there is another example of a time interval of 4 weeks being used to evaluate the test-retest reliability of a self-questionnaire in Korean patients with schizophrenia [43]. Despite these limitations, our study has the value of offering evidence that the Korean version of the TLC scale is a reliable and valid psychometric tool, as well as identifying potential cut-off values for the presence of FTD or disorganized speech in schizophrenia patients. Hence, the Korean version of the TLC scale is a promising method of scoring the symptoms of FTD or disorganized speech in schizophrenia patients as a basis for psychopathological, neuroimaging and other neurobiological investigations.

Role of the funding source Our study was supported by the Choi Shin-Hai Neuropsychiatry Research Fund (2013) of the Korean Foundation of Neuropsychiatry Research. The funding source had no further role in the study design, in the collection, analysis and interpretation of the data, in the writing of the report or in the decision to submit the paper for publication.

Conflicts of interest None. Acknowledgment We would like to thank and acknowledge the following people who contributed to the data collection and environment for the study: Drs. Seong-Su Kim, Chang-Seok Lee, Ki Won Kim, Hyeon-Joo Yu, Seung-Min Han, Il-Joon Yi, Bomi Kim, and Jeong-Min Yu. We also would like to thank Joohwa Jeong for the backward translation of the Scale for the Assessment of Thought, Language, and Communication.

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Reliability and validity of the Korean version of the Scale for the Assessment of Thought, Language, and Communication.

Our study aimed to assess the inter-rater and test-retest reliability, as well as concurrent and convergent validity, of the Korean version of the Sca...
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