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International Journal of Urology (2014) 21, 1151–1154
doi: 10.1111/iju.12522
Original Article: Clinical Investigation
Core lower urinary tract symptom score questionnaire: A psychometric analysis Kikuo Okamura,1 Kyosuke Kimura,2 Hideki Mizuno,2 Noriko Okamoto2 and Yasuhiro Aota2 1
Department of Urology, National Hospital Organization Higashi Nagoya Hospital, and 2Department of Urology, National Hospital Organization Nagoya Medical Center, Nagoya, Japan
Abbreviations & Acronyms BP = pain in the bladder CLSS = core lower urinary symptom score DF = daytime frequency ICI = International Consultation on Incontinence ICIQ-SF = International Consultation on Incontinence Questionnaire Short-form IE = feeling of incomplete emptying IPSS = International prostate symptom score LUTS = lower urinary tract symptoms OAB = overactive bladder OABSS = overactive bladder symptom score SS = slow urinary stream SUI = stress urinary incontinence UP = pain in the urethra UUI = urgency urinary incontinence Correspondence: Kikuo Okamura M.D., Ph.D., Department of Urology, Higashi Nagoya National Hospital, 5-101 Umemorizaka, Meitou-ku, Nagoya 465-8620, Japan. Email: [email protected] Received 27 December 2013; accepted 6 May 2014. Online publication 19 June 2014
Objectives: To analyze the reliability and validity of the Japanese version of the core lower urinary symptom score questionnaire with psychometric methods. Method: The present study included 140 women and 125 men who filled in a core lower urinary symptom score questionnaire while attending two lectures on lower urinary tract symptoms. Missing response rates to individual questions were 1.5–5.3%. After the descriptive analyses including box plot, Cronbach’s α coefficients and Spearman’s ρ were calculated for reliability and validity assessment, respectively. Factor analysis was also carried out to explore the underlying structure. Results: Of the scores for 10 core symptoms, the interquartile range for pain in the bladder and urethra was 0 in both sexes, and that for stress incontinence was 0 in men. Cronbach’s α of the core lower urinary symptom score was 0.733 in women and 0.721 in men. Questions regarding daytime frequency, nocturia, urgency and urgency urinary incontinence, and those on slow stream, straining and feeling of incomplete emptying were significantly correlated with each other in both sexes. Pain in the urethra and bladder showed more extensive associations in women than in men. Factor analysis showed four components in both sexes: the first was storage symptoms, second was voiding symptoms, third was pain and the fourth was urinary incontinence. Conclusions: The core lower urinary symptom score questionnaire shows good reliability and validity for both sexes, and it could be used as screening tool for lower urinary tract symptoms in any clinical setting or epidemiological investigation.
Key words: core lower urinary tract symptom score, psychometric analysis, reliability, validity.
Introduction To assess the overall LUTS of patients visiting clinics or those of people in epidemiological surveys, it has been necessary to use several validated questionnaires to date: IPSS questionnaire, OABSS questionnaire and/or ICIQ-SF.1–6 The ICI recommended the use of the ICIMaleSF questionnaire for men and ICIFemaleSF for women on assessing LUTS; however, they could contain too extensive or variable questions.7–9 The CLSS questionnaire was reported by Homma et al. in 2008.10 It contains 10 questions regarding five storage symptoms (daytime frequency, nocturia, urinary urgency, urgency urinary incontinence and stress urinary incontinence), three voiding symptoms (slow urinary stream, need to strain and feeling of incomplete empting), pain in the bladder and urethra, and one question on the burden caused by LUTS. These 10 symptoms were selected from 25 symptoms defined by the International Continence Society standardization committee. The clinical usefulness of the CLSS questionnaire has already been validated in female LUTS, male LUTS and for assessment of the outcome on administering silodosin for benign prostate hyperplasia.11–13 The reliability and validity of the questionnaire should have been confirmed by the standard psychometric procedure before general use; however, the psychometric properties of the CLSS questionnaire have not been elucidated. In the present study, we carried out psychometric analysis of the Japanese version of the questionnaire for both men and women.
Methods We used two samples to assess the reliability and validity of the CLSS. The samples were collected from the residents of two towns (Higashiura and Umemorizaka) attending a lecture on LUTS. There were 168 participants in the former and 210 in the latter. All attendees received the © 2014 The Japanese Urological Association
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Table 1
CLSS scores in two samples Women
n DF Nocturia Urgency UUI SUI SS Straining IE BP UP Bother
Men
Higashiura
Umemorizaka
Higashiura
Umemorizaka
79 1.0 ± 0.8 1.1 ± 0.8 0.7 ± 0.7 0.5 ± 0.7 0.9 ± 0.9 0.8 ± 1.0 0.4 ± 0.7 0.4 ± 0.7 0.1 ± 0.3 0.0 ± 0.2 3.0 ± 1.7
61 0.9 ± 0.7 1.1 ± 0.8 0.7 ± 0.7 0.3 ± 0.5 0.5 ± 0.7 0.8 ± 0.9 0.4 ± 0.8 0.4 ± 0.7 0.1 ± 0.3 0.0 ± 0.3 2.5 ± 1.7
63 0.9 ± 0.8 1.6 ± 0.8 0.9 ± 0.8 0.4 ± 0.7 0.0 ± 0.0 1.5 ± 1.1 0.9 ± 1.0 0.7 ± 0.8 0.1 ± 0.3 0.1 ± 0.3 3.1 ± 1.6
62 0.8 ± 0.7 1.5 ± 0.8 0.7 ± 0.8 0.3 ± 0.3 0.1 ± 0.3 1.4 ± 1.1 0.7 ± 1.0 0.7 ± 1.0 0.1 ± 0.4 0.2 ± 0.5 3.2 ± 1.5
self-administered CLSS questionnaire and were asked to complete it after being informed verbally that a study of the psychometric properties of the CLSS would be carried out, and the completed questionnaires would be collected anonymously from participants who consented. The present study was approved by the ethical committee of Higashi Nagoya Hospital. In the present study, the Japanese version of the CLSS questionnaire was used, whereas the English version was reported elsewhere.14 The score for each question ranged from 0 to 3, and the total score ranged from 0 (none) to 30 (maximal symptoms). A bother index was also used: 0 (delighted) to 6 (terrible). Descriptive statistics and box plots were carried out to evaluate the distribution of each response. For reliability assessment based on internal consistency, Cronbach’s α coefficient was calculated. Correlations were calculated based on Spearman’s ρ coefficient among CLSS items to confirm convergent and discriminant validity. Additionally, using factor analysis (alpha factoring, Scree plot and promax rotation), the construct validity of the CLSS was investigated. As factor loading of a CLSS item increases up to 1.00, such an item would be an important factor in structures extracted from the analysis. In the present study, factor loading greater than 0.40 was considered significant. These psychometric analyses were carried out by sex. The CLSS questionnaire included one question asking respondents to list a maximum of three bothersome symptoms out of 10 symptoms and one question on the most bothersome symptom of the three core symptoms. We investigated the relationships between the responses to the aforementioned two questions. SPSS version 20 was used for statistical analysis, and P-values less than 0.05 were considered significant.
Results The questionnaires were collected from 79 women and 63 men in Higashiura, and 61 women and 62 men in Umemorizaka. The response rate was 84.5% in the former and 63.3% in the latter. The average age of men was 71.1 ± 8.6 years in Higashiura and 71.7 ± 10.8 years in Umemorizaka, and that of women was 65.9 ± 9.1 years and 68.4 ± 9.4 years, respectively. There were no significant differences in the age or sex between the two samples. Table 1 shows each score of the CLSS and the bother 1152
index. Almost all scores were similar between the two samples. Missing response rates to individual items were 1.5–5.3%. Figure 1 shows the distributions of responses to the questions on the 10 symptoms, and that on the bother for both sexes. Of the scores for the 10 core symptoms, the interquartile range for pain in the bladder and urethra was 0 in both sexes, and that for stress incontinence was also 0 in men. Cronbach’s α was 0.721 in men and 0.733 in women, showing good internal consistency. Table 2 shows Spearman’s ρ among the items of the CLSS questionnaire. Questions regarding daytime frequency, nocturia, urinary urgency and urgency urinary incontinence, and those regarding slow stream, straining and feeling of incomplete emptying were significantly correlated with each other in both sexes. However, in women, pain in the bladder and urethra showed more extensive associations with nocturia, urgency, urgency urinary incontinence, slow stream and incomplete emptying than in men. The bother index was significantly correlated with many items of the CLSS questionnaire in both sexes. These results show the convergent and discriminant validity of the CLSS questionnaire. As shown in Table 3, factor analysis determined four components: storage symptoms (factor 1), voiding symptoms (factor 2), pain (factor 3) and urinary incontinence (factor 4), in both sexes. Although factor 4 included stress and urgency urinary incontinence in women, it included only stress urinary incontinence in men. Urgency urinary incontinence was included in factors 1 and 4 in women, but was included in factor 1 alone in men. As shown in Table 4, the response to the question on the three core symptoms was blank in 15 (5.9%) attendees. Just 130 attendees (49.1%) selected their most burdensome symptom as being from their three core symptoms, 100 (37.8%) selected their most burdensome symptom from other than their three core symptoms, and 23 (8.7%) did not determine the primary symptom.
Discussion The psychometric properties of the newly-developed questionnaire were confirmed by: (i) test–retest reproducibility using the κ coefficient; (ii) reliability by internal consistency using Cronbach’s α; (iii) convergent and/or discriminant validity using correlation analysis among items in a questionnaire with/ without factor analysis; and (iv) examination of the responsiveness regarding the change after treatment. Homma et al. had already confirmed the test–retest reliability when developing the CLSS questionnaire.10 In the present study, we carried out (ii) and (iii) of the four aforementioned analyses. Responsiveness might be shown in the future. The CLSS questionnaire was reliable for both men and women because of good internal consistency, with Cronbach’s α being greater than 0.7. Generally, a Cronbach’s α value of 0.7 or greater is acceptable.15 Correlation analysis showed favorable convergence and discriminant validity in both sexes. However, in women, correlations among CLSS questions were more complicated, mainly caused by many associations between pain and storage/voiding symptoms. We did not observe such associations when investigating female LUTS using the IPSS questionnaire.2 This could be caused by the fact that the CLSS questionnaire includes © 2014 The Japanese Urological Association
Psychometric analysis of CLSS
(b)
6
6
Table 2
1
0
0
Bo th er
1
IE BP UP
2
ra
2
No DF ct Ur uria ge nc y UU I SU I
3
U Bo P th er
3
IE BP
4
St SS ra in in g
4
No DF ct Ur uria ge nc y UU I SU I
Fig. 1 Distribution of scores for (a) men and (b) women of core lower urinary tract symptoms and bother. Te box plots show median (bold horizontal bar), interquartile range (25–75%), and whiskers and minimal scores.
5
5
SS in in g
Women
Men
St
(a)
Correlation coefficients (Spearman’s ρ) of items of the core lower urinary tract symptom score
Men
DF Nocturia Urgency UUI SUI SS Straining IE BP UP Bother
Table 3
DF
Nocturia
Urgency
UUI
SUI
SS
Straining
IE
BP
UP
Bother
1 0.23 0.35 0.22 0.26 0.02 −0.05 0.18 0.03 0.07 0.30
0.31 1 0.25 0.35 0.20 0.26 0.20 0.14 0.29 0.30 0.36
0.37 0.38 1 0.36 0.13 0.13 −0.14 0.23 0.23 0.27 0.35
0.35 0.22 0.46 1 0.43 0.01 0.13 0.17 0.30 0.36 0.46
0.17 −0.13 −0.05 0.08 1 0.22 0.32 0.18 0.11 0.10 0.43
−0.04 0.17 0.30 0.01 −0.03 1 0.41 0.45 0.25 0.20 0.37
0.02 0.17 0.23 0.04 −0.01 0.44 1 0.40 0.03 0.02 0.35
0.05 0.19 0.24 0.06 −0.01 0.38 0.21 1 0.31 0.29 0.35
−0.01 0.04 −0.04 0.03 −0.04 −0.03 −0.02 0.08 1 0.89 0.14
−0.08 0.09 0.01 −0.10 −0.05 0.17 −0.01 0.18 0.19 1 0.14
0.29 0.45 0.45 0.42 −0.05 0.41 0.24 0.24 0.13 0.06 1
Factor analysis
Women
1
2
3
4
Men
1
2
3
4
DF Nocturia Urgency UUI SUI SS Straining IE BP UP
0.72 0.46 0.84 0.43 0.11 0.09 −0.28 0.27 0.21 0.26
0.05 0.23 0.05 0.07 0.31 0.80 0.78 0.78 0.20 0.16
0.00 0.38 0.32 0.38 0.02 0.22 −0.07 0.26 0.95 0.95
0.34 0.47 0.12 0.73 0.87 0.21 0.38 0.16 0.15 0.18
DF Nocturia Urgency UUI SUI SS Straining IE BP UP
0.72 0.58 0.78 0.79 0.05 0.13 0.20 0.20 0.05 −0.14
−0.03 0.34 0.40 0.06 −0.07 0.84 0.67 0.66 −0.06 0.36
−0.18 −0.05 0.01 0.10 −0.06 0.05 −0.26 0.30 0.84 0.48
0.28 −0.36 −0.18 0.07 0.93 −0.14 −0.07 −0.06 −0.01 −0.18
questions regarding pain and urinary incontinence. We speculate that pelvic floor dysfunction might affect this in women. Fujimura et al. suggested that the CLSS questionnaire facilitates a more comprehensive assessment of female LUTS than the IPSS.12 Factor analysis determined four structure components in both sexes, as we anticipated. The first was associated with storage symptoms, the second voiding symptoms, the third pain and the © 2014 The Japanese Urological Association
fourth urinary incontinence. In men, only stress urinary incontinence was included in the fourth component. This might be due to the fact that the prevalence of stress urinary incontinence is very low in men, with it being caused by a different mechanism from urgency urinary incontinence. In contrast, mixed urinary incontinence is prevalent in women. We considered that factor analysis shown excellent constructive validity of the CLSS questionnaire in both sexes. 1153
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Table 4 Relationship between the three core symptoms and primary core symptom Total
No. 3 core symptoms chosen
3 2 1 0 Blank Total
62 53 77 58 15 265
In the CLSS questionnaire, the responder must list a maximum of three symptoms causing a burden and then choose the most bothersome from a list of 10 core symptoms. However, less than half selected the most bothersome symptom from their three core symptoms. The significance of the three core and/or one core question must be assessed in the future. Three possible limitations existed in the present study: (i) the small number of cases; (ii) including participants of two towns; and (iii) participants who were residents and not patients. The first might be acceptable, because Kline showed that the sample size should be more than 100.15 The second might also be acceptable because of the similarity in the participants’ backgrounds. Regarding the third, the analysis might be confirmed using patients in clinics. However, we could show the reliability and validity using a sample of residents whose LUTS might be modest compared with patients visiting clinics. It is suggested that the CLSS questionnaire is useful even in an epidemiological study.
Conflict of interest None declared.
References 1 Homma Y, Tsukamoto T, Yasuda K, Ozona S, Yoshida M, Yamaguchi T. Evaluation of psychometric properties of Japanese version of International Prostate Symptom Score and BPH Impact Index. Nihon Hinyokika Gakkai Zasshi 2003; 94: 560–9. (In Japanese.) 2 Okamura K, Nojiri Y, Osuga Y, Tange C. Psychometric analysis of international prostate symptom score for female lower urinary tract symptoms. Urology 2009; 73: 1199–202. 3 Homma Y, Yoshida M, Seki N et al. Symptom assessment tool for overactive bladder syndrome-overactive bladder symptom score. Urology 2006; 68: 318–23.
Core 1 symptom selected from
Core 1 symptom
3 Core
Other than 3 core
0
Blank
46 38 46 0 0 130
11 6 25 56 2 100
5 9 6 2 1 23
0 0 0 0 12 12
4 Gotoh M, Homma Y, Funahashi Y, Matsukawa Y, Kato M. Psychometric validation of the Japanese version of the International Consultation on Incontinence Questionnaire-Short Form. Int. J. Urol. 2009; 16: 303–6. 5 Osuga Y, Okamura K, Ando F, Shimokata H. Prevalence of lower urinary tract symptoms in middle-aged and elderly Japanese. Geriatr. Gerontol. Int. 2013; 13: 1010–17. 6 Okamura K, Usami T, Nagahama, Maruyama S, Mizuta E. The relationships among filling, voiding subscores from international prostatic symptom score and quality of life in Japanese elderly men and women. Eur. Urol. 2002; 42: 498–505. 7 Abrams P, Avery K, Gardener N, Donovan J. The International Consultation on Incontinence Modular Questionnaire: www.iciq.net. J. Urol. 2006; 175 (3 Pt 1): 1063–6. 8 Donovan JL, Peters TJ, Abrams P, Brookes ST, De La Rosette JJMCH, Schafer W. Scoring the short form ICSmaleSF questionnaire. International Continence Society. J. Urol. 2000; 164: 1948–55. 9 Brookes ST, Donovan JL, Wright M, Jackson S, Abrams P. A scored form of the Bristol Female Lower Urinary Tract Symptoms questionnaire: data from a randomized controlled trial of surgery for women with stress incontinence. Am. J. Obstet. Gynecol. 2004; 191: 73–82. 10 Homma Y, Yoshida M, Yamanishi T, Gotoh M. Core Lower Urinary Tract Symptom score (CLSS) questionnaire: a reliable tool in the overall assessment of lower urinary tract symptoms. Int. J. Urol. 2008; 15: 816–20. 11 Fujimura T, Kume H, Nishimatsu H et al. Assessment of lower urinary tract symptoms in men by international prostate symptom score and core lower urinary tract symptom score. BJU Int. 2011; 109: 1512–17. 12 Fujimura T, Kume H, Tsurumaki Y et al. Core lower urinary tract symptom score (CLSS) for the assessment of female lower urinary tract symptoms: a comparative study. Int. J. Urol. 2011; 18: 778–84. 13 Ito H, Sano F, Ogawa T, Yao M. Evaluation and validation of the core lower urinary tract symptom score as an outcome assessment tool for the treatment of benign prostatic hyperplasia: effects of the α1-adrenoreceptor antagonist silodosin. Int. J. Urol. 2014; 21: 108–12. 14 Homma Y, Araki I, Igawa Y et al.; Japanese Society of Neurogenic Bladder. Clinical guideline for male lower urinary tract symptoms. Int. J. Urol. 2009; 16: 775–90. 15 Kline P. Psychometric theory and method. In: Kline P (ed.). Handbook of Psychological Testing. Routledge, London, 2000; 7–16.
Editorial Comment Editorial Comment to Core lower urinary tract symptom score questionnaire: A psychometric analysis The core lower urinary tract symptom score (CLSS) questionnaire was recently developed by Dr Homma’s group,1 and had been used as a reliable instrument for lower urinary tract symptoms (LUTS) assessment in several studies.2,3 However, the psychometric properties of the CLSS still need to be further 1154
evaluated. It is well known that a newly developed measure should show validity and reliability. In the present study, the authors analyzed psychometric properties of CLSS by using common and simple methods. Although reliability can be calculated in various ways, the most widely accepted measure is © 2014 The Japanese Urological Association
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International Journal of Urology (2014) 21, 1151–1154
doi: 10.1111/iju.12522
Original Article: Clinical Investigation
Core lower urinary tract symptom score questionnaire: A psychometric analysis Kikuo Okamura,1 Kyosuke Kimura,2 Hideki Mizuno,2 Noriko Okamoto2 and Yasuhiro Aota2 1
Department of Urology, National Hospital Organization Higashi Nagoya Hospital, and 2Department of Urology, National Hospital Organization Nagoya Medical Center, Nagoya, Japan
Abbreviations & Acronyms BP = pain in the bladder CLSS = core lower urinary symptom score DF = daytime frequency ICI = International Consultation on Incontinence ICIQ-SF = International Consultation on Incontinence Questionnaire Short-form IE = feeling of incomplete emptying IPSS = International prostate symptom score LUTS = lower urinary tract symptoms OAB = overactive bladder OABSS = overactive bladder symptom score SS = slow urinary stream SUI = stress urinary incontinence UP = pain in the urethra UUI = urgency urinary incontinence Correspondence: Kikuo Okamura M.D., Ph.D., Department of Urology, Higashi Nagoya National Hospital, 5-101 Umemorizaka, Meitou-ku, Nagoya 465-8620, Japan. Email: [email protected] Received 27 December 2013; accepted 6 May 2014. Online publication 19 June 2014
Objectives: To analyze the reliability and validity of the Japanese version of the core lower urinary symptom score questionnaire with psychometric methods. Method: The present study included 140 women and 125 men who filled in a core lower urinary symptom score questionnaire while attending two lectures on lower urinary tract symptoms. Missing response rates to individual questions were 1.5–5.3%. After the descriptive analyses including box plot, Cronbach’s α coefficients and Spearman’s ρ were calculated for reliability and validity assessment, respectively. Factor analysis was also carried out to explore the underlying structure. Results: Of the scores for 10 core symptoms, the interquartile range for pain in the bladder and urethra was 0 in both sexes, and that for stress incontinence was 0 in men. Cronbach’s α of the core lower urinary symptom score was 0.733 in women and 0.721 in men. Questions regarding daytime frequency, nocturia, urgency and urgency urinary incontinence, and those on slow stream, straining and feeling of incomplete emptying were significantly correlated with each other in both sexes. Pain in the urethra and bladder showed more extensive associations in women than in men. Factor analysis showed four components in both sexes: the first was storage symptoms, second was voiding symptoms, third was pain and the fourth was urinary incontinence. Conclusions: The core lower urinary symptom score questionnaire shows good reliability and validity for both sexes, and it could be used as screening tool for lower urinary tract symptoms in any clinical setting or epidemiological investigation.
Key words: core lower urinary tract symptom score, psychometric analysis, reliability, validity.
Introduction To assess the overall LUTS of patients visiting clinics or those of people in epidemiological surveys, it has been necessary to use several validated questionnaires to date: IPSS questionnaire, OABSS questionnaire and/or ICIQ-SF.1–6 The ICI recommended the use of the ICIMaleSF questionnaire for men and ICIFemaleSF for women on assessing LUTS; however, they could contain too extensive or variable questions.7–9 The CLSS questionnaire was reported by Homma et al. in 2008.10 It contains 10 questions regarding five storage symptoms (daytime frequency, nocturia, urinary urgency, urgency urinary incontinence and stress urinary incontinence), three voiding symptoms (slow urinary stream, need to strain and feeling of incomplete empting), pain in the bladder and urethra, and one question on the burden caused by LUTS. These 10 symptoms were selected from 25 symptoms defined by the International Continence Society standardization committee. The clinical usefulness of the CLSS questionnaire has already been validated in female LUTS, male LUTS and for assessment of the outcome on administering silodosin for benign prostate hyperplasia.11–13 The reliability and validity of the questionnaire should have been confirmed by the standard psychometric procedure before general use; however, the psychometric properties of the CLSS questionnaire have not been elucidated. In the present study, we carried out psychometric analysis of the Japanese version of the questionnaire for both men and women.
Methods We used two samples to assess the reliability and validity of the CLSS. The samples were collected from the residents of two towns (Higashiura and Umemorizaka) attending a lecture on LUTS. There were 168 participants in the former and 210 in the latter. All attendees received the © 2014 The Japanese Urological Association
1151
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Table 1
CLSS scores in two samples Women
n DF Nocturia Urgency UUI SUI SS Straining IE BP UP Bother
Men
Higashiura
Umemorizaka
Higashiura
Umemorizaka
79 1.0 ± 0.8 1.1 ± 0.8 0.7 ± 0.7 0.5 ± 0.7 0.9 ± 0.9 0.8 ± 1.0 0.4 ± 0.7 0.4 ± 0.7 0.1 ± 0.3 0.0 ± 0.2 3.0 ± 1.7
61 0.9 ± 0.7 1.1 ± 0.8 0.7 ± 0.7 0.3 ± 0.5 0.5 ± 0.7 0.8 ± 0.9 0.4 ± 0.8 0.4 ± 0.7 0.1 ± 0.3 0.0 ± 0.3 2.5 ± 1.7
63 0.9 ± 0.8 1.6 ± 0.8 0.9 ± 0.8 0.4 ± 0.7 0.0 ± 0.0 1.5 ± 1.1 0.9 ± 1.0 0.7 ± 0.8 0.1 ± 0.3 0.1 ± 0.3 3.1 ± 1.6
62 0.8 ± 0.7 1.5 ± 0.8 0.7 ± 0.8 0.3 ± 0.3 0.1 ± 0.3 1.4 ± 1.1 0.7 ± 1.0 0.7 ± 1.0 0.1 ± 0.4 0.2 ± 0.5 3.2 ± 1.5
self-administered CLSS questionnaire and were asked to complete it after being informed verbally that a study of the psychometric properties of the CLSS would be carried out, and the completed questionnaires would be collected anonymously from participants who consented. The present study was approved by the ethical committee of Higashi Nagoya Hospital. In the present study, the Japanese version of the CLSS questionnaire was used, whereas the English version was reported elsewhere.14 The score for each question ranged from 0 to 3, and the total score ranged from 0 (none) to 30 (maximal symptoms). A bother index was also used: 0 (delighted) to 6 (terrible). Descriptive statistics and box plots were carried out to evaluate the distribution of each response. For reliability assessment based on internal consistency, Cronbach’s α coefficient was calculated. Correlations were calculated based on Spearman’s ρ coefficient among CLSS items to confirm convergent and discriminant validity. Additionally, using factor analysis (alpha factoring, Scree plot and promax rotation), the construct validity of the CLSS was investigated. As factor loading of a CLSS item increases up to 1.00, such an item would be an important factor in structures extracted from the analysis. In the present study, factor loading greater than 0.40 was considered significant. These psychometric analyses were carried out by sex. The CLSS questionnaire included one question asking respondents to list a maximum of three bothersome symptoms out of 10 symptoms and one question on the most bothersome symptom of the three core symptoms. We investigated the relationships between the responses to the aforementioned two questions. SPSS version 20 was used for statistical analysis, and P-values less than 0.05 were considered significant.
Results The questionnaires were collected from 79 women and 63 men in Higashiura, and 61 women and 62 men in Umemorizaka. The response rate was 84.5% in the former and 63.3% in the latter. The average age of men was 71.1 ± 8.6 years in Higashiura and 71.7 ± 10.8 years in Umemorizaka, and that of women was 65.9 ± 9.1 years and 68.4 ± 9.4 years, respectively. There were no significant differences in the age or sex between the two samples. Table 1 shows each score of the CLSS and the bother 1152
index. Almost all scores were similar between the two samples. Missing response rates to individual items were 1.5–5.3%. Figure 1 shows the distributions of responses to the questions on the 10 symptoms, and that on the bother for both sexes. Of the scores for the 10 core symptoms, the interquartile range for pain in the bladder and urethra was 0 in both sexes, and that for stress incontinence was also 0 in men. Cronbach’s α was 0.721 in men and 0.733 in women, showing good internal consistency. Table 2 shows Spearman’s ρ among the items of the CLSS questionnaire. Questions regarding daytime frequency, nocturia, urinary urgency and urgency urinary incontinence, and those regarding slow stream, straining and feeling of incomplete emptying were significantly correlated with each other in both sexes. However, in women, pain in the bladder and urethra showed more extensive associations with nocturia, urgency, urgency urinary incontinence, slow stream and incomplete emptying than in men. The bother index was significantly correlated with many items of the CLSS questionnaire in both sexes. These results show the convergent and discriminant validity of the CLSS questionnaire. As shown in Table 3, factor analysis determined four components: storage symptoms (factor 1), voiding symptoms (factor 2), pain (factor 3) and urinary incontinence (factor 4), in both sexes. Although factor 4 included stress and urgency urinary incontinence in women, it included only stress urinary incontinence in men. Urgency urinary incontinence was included in factors 1 and 4 in women, but was included in factor 1 alone in men. As shown in Table 4, the response to the question on the three core symptoms was blank in 15 (5.9%) attendees. Just 130 attendees (49.1%) selected their most burdensome symptom as being from their three core symptoms, 100 (37.8%) selected their most burdensome symptom from other than their three core symptoms, and 23 (8.7%) did not determine the primary symptom.
Discussion The psychometric properties of the newly-developed questionnaire were confirmed by: (i) test–retest reproducibility using the κ coefficient; (ii) reliability by internal consistency using Cronbach’s α; (iii) convergent and/or discriminant validity using correlation analysis among items in a questionnaire with/ without factor analysis; and (iv) examination of the responsiveness regarding the change after treatment. Homma et al. had already confirmed the test–retest reliability when developing the CLSS questionnaire.10 In the present study, we carried out (ii) and (iii) of the four aforementioned analyses. Responsiveness might be shown in the future. The CLSS questionnaire was reliable for both men and women because of good internal consistency, with Cronbach’s α being greater than 0.7. Generally, a Cronbach’s α value of 0.7 or greater is acceptable.15 Correlation analysis showed favorable convergence and discriminant validity in both sexes. However, in women, correlations among CLSS questions were more complicated, mainly caused by many associations between pain and storage/voiding symptoms. We did not observe such associations when investigating female LUTS using the IPSS questionnaire.2 This could be caused by the fact that the CLSS questionnaire includes © 2014 The Japanese Urological Association
Psychometric analysis of CLSS
(b)
6
6
Table 2
1
0
0
Bo th er
1
IE BP UP
2
ra
2
No DF ct Ur uria ge nc y UU I SU I
3
U Bo P th er
3
IE BP
4
St SS ra in in g
4
No DF ct Ur uria ge nc y UU I SU I
Fig. 1 Distribution of scores for (a) men and (b) women of core lower urinary tract symptoms and bother. Te box plots show median (bold horizontal bar), interquartile range (25–75%), and whiskers and minimal scores.
5
5
SS in in g
Women
Men
St
(a)
Correlation coefficients (Spearman’s ρ) of items of the core lower urinary tract symptom score
Men
DF Nocturia Urgency UUI SUI SS Straining IE BP UP Bother
Table 3
DF
Nocturia
Urgency
UUI
SUI
SS
Straining
IE
BP
UP
Bother
1 0.23 0.35 0.22 0.26 0.02 −0.05 0.18 0.03 0.07 0.30
0.31 1 0.25 0.35 0.20 0.26 0.20 0.14 0.29 0.30 0.36
0.37 0.38 1 0.36 0.13 0.13 −0.14 0.23 0.23 0.27 0.35
0.35 0.22 0.46 1 0.43 0.01 0.13 0.17 0.30 0.36 0.46
0.17 −0.13 −0.05 0.08 1 0.22 0.32 0.18 0.11 0.10 0.43
−0.04 0.17 0.30 0.01 −0.03 1 0.41 0.45 0.25 0.20 0.37
0.02 0.17 0.23 0.04 −0.01 0.44 1 0.40 0.03 0.02 0.35
0.05 0.19 0.24 0.06 −0.01 0.38 0.21 1 0.31 0.29 0.35
−0.01 0.04 −0.04 0.03 −0.04 −0.03 −0.02 0.08 1 0.89 0.14
−0.08 0.09 0.01 −0.10 −0.05 0.17 −0.01 0.18 0.19 1 0.14
0.29 0.45 0.45 0.42 −0.05 0.41 0.24 0.24 0.13 0.06 1
Factor analysis
Women
1
2
3
4
Men
1
2
3
4
DF Nocturia Urgency UUI SUI SS Straining IE BP UP
0.72 0.46 0.84 0.43 0.11 0.09 −0.28 0.27 0.21 0.26
0.05 0.23 0.05 0.07 0.31 0.80 0.78 0.78 0.20 0.16
0.00 0.38 0.32 0.38 0.02 0.22 −0.07 0.26 0.95 0.95
0.34 0.47 0.12 0.73 0.87 0.21 0.38 0.16 0.15 0.18
DF Nocturia Urgency UUI SUI SS Straining IE BP UP
0.72 0.58 0.78 0.79 0.05 0.13 0.20 0.20 0.05 −0.14
−0.03 0.34 0.40 0.06 −0.07 0.84 0.67 0.66 −0.06 0.36
−0.18 −0.05 0.01 0.10 −0.06 0.05 −0.26 0.30 0.84 0.48
0.28 −0.36 −0.18 0.07 0.93 −0.14 −0.07 −0.06 −0.01 −0.18
questions regarding pain and urinary incontinence. We speculate that pelvic floor dysfunction might affect this in women. Fujimura et al. suggested that the CLSS questionnaire facilitates a more comprehensive assessment of female LUTS than the IPSS.12 Factor analysis determined four structure components in both sexes, as we anticipated. The first was associated with storage symptoms, the second voiding symptoms, the third pain and the © 2014 The Japanese Urological Association
fourth urinary incontinence. In men, only stress urinary incontinence was included in the fourth component. This might be due to the fact that the prevalence of stress urinary incontinence is very low in men, with it being caused by a different mechanism from urgency urinary incontinence. In contrast, mixed urinary incontinence is prevalent in women. We considered that factor analysis shown excellent constructive validity of the CLSS questionnaire in both sexes. 1153
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K OKAMURA ET AL.
Table 4 Relationship between the three core symptoms and primary core symptom Total
No. 3 core symptoms chosen
3 2 1 0 Blank Total
62 53 77 58 15 265
In the CLSS questionnaire, the responder must list a maximum of three symptoms causing a burden and then choose the most bothersome from a list of 10 core symptoms. However, less than half selected the most bothersome symptom from their three core symptoms. The significance of the three core and/or one core question must be assessed in the future. Three possible limitations existed in the present study: (i) the small number of cases; (ii) including participants of two towns; and (iii) participants who were residents and not patients. The first might be acceptable, because Kline showed that the sample size should be more than 100.15 The second might also be acceptable because of the similarity in the participants’ backgrounds. Regarding the third, the analysis might be confirmed using patients in clinics. However, we could show the reliability and validity using a sample of residents whose LUTS might be modest compared with patients visiting clinics. It is suggested that the CLSS questionnaire is useful even in an epidemiological study.
Conflict of interest None declared.
References 1 Homma Y, Tsukamoto T, Yasuda K, Ozona S, Yoshida M, Yamaguchi T. Evaluation of psychometric properties of Japanese version of International Prostate Symptom Score and BPH Impact Index. Nihon Hinyokika Gakkai Zasshi 2003; 94: 560–9. (In Japanese.) 2 Okamura K, Nojiri Y, Osuga Y, Tange C. Psychometric analysis of international prostate symptom score for female lower urinary tract symptoms. Urology 2009; 73: 1199–202. 3 Homma Y, Yoshida M, Seki N et al. Symptom assessment tool for overactive bladder syndrome-overactive bladder symptom score. Urology 2006; 68: 318–23.
Core 1 symptom selected from
Core 1 symptom
3 Core
Other than 3 core
0
Blank
46 38 46 0 0 130
11 6 25 56 2 100
5 9 6 2 1 23
0 0 0 0 12 12
4 Gotoh M, Homma Y, Funahashi Y, Matsukawa Y, Kato M. Psychometric validation of the Japanese version of the International Consultation on Incontinence Questionnaire-Short Form. Int. J. Urol. 2009; 16: 303–6. 5 Osuga Y, Okamura K, Ando F, Shimokata H. Prevalence of lower urinary tract symptoms in middle-aged and elderly Japanese. Geriatr. Gerontol. Int. 2013; 13: 1010–17. 6 Okamura K, Usami T, Nagahama, Maruyama S, Mizuta E. The relationships among filling, voiding subscores from international prostatic symptom score and quality of life in Japanese elderly men and women. Eur. Urol. 2002; 42: 498–505. 7 Abrams P, Avery K, Gardener N, Donovan J. The International Consultation on Incontinence Modular Questionnaire: www.iciq.net. J. Urol. 2006; 175 (3 Pt 1): 1063–6. 8 Donovan JL, Peters TJ, Abrams P, Brookes ST, De La Rosette JJMCH, Schafer W. Scoring the short form ICSmaleSF questionnaire. International Continence Society. J. Urol. 2000; 164: 1948–55. 9 Brookes ST, Donovan JL, Wright M, Jackson S, Abrams P. A scored form of the Bristol Female Lower Urinary Tract Symptoms questionnaire: data from a randomized controlled trial of surgery for women with stress incontinence. Am. J. Obstet. Gynecol. 2004; 191: 73–82. 10 Homma Y, Yoshida M, Yamanishi T, Gotoh M. Core Lower Urinary Tract Symptom score (CLSS) questionnaire: a reliable tool in the overall assessment of lower urinary tract symptoms. Int. J. Urol. 2008; 15: 816–20. 11 Fujimura T, Kume H, Nishimatsu H et al. Assessment of lower urinary tract symptoms in men by international prostate symptom score and core lower urinary tract symptom score. BJU Int. 2011; 109: 1512–17. 12 Fujimura T, Kume H, Tsurumaki Y et al. Core lower urinary tract symptom score (CLSS) for the assessment of female lower urinary tract symptoms: a comparative study. Int. J. Urol. 2011; 18: 778–84. 13 Ito H, Sano F, Ogawa T, Yao M. Evaluation and validation of the core lower urinary tract symptom score as an outcome assessment tool for the treatment of benign prostatic hyperplasia: effects of the α1-adrenoreceptor antagonist silodosin. Int. J. Urol. 2014; 21: 108–12. 14 Homma Y, Araki I, Igawa Y et al.; Japanese Society of Neurogenic Bladder. Clinical guideline for male lower urinary tract symptoms. Int. J. Urol. 2009; 16: 775–90. 15 Kline P. Psychometric theory and method. In: Kline P (ed.). Handbook of Psychological Testing. Routledge, London, 2000; 7–16.
Editorial Comment Editorial Comment to Core lower urinary tract symptom score questionnaire: A psychometric analysis The core lower urinary tract symptom score (CLSS) questionnaire was recently developed by Dr Homma’s group,1 and had been used as a reliable instrument for lower urinary tract symptoms (LUTS) assessment in several studies.2,3 However, the psychometric properties of the CLSS still need to be further 1154
evaluated. It is well known that a newly developed measure should show validity and reliability. In the present study, the authors analyzed psychometric properties of CLSS by using common and simple methods. Although reliability can be calculated in various ways, the most widely accepted measure is © 2014 The Japanese Urological Association
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