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Adaptation and Validation of the Voice-Related Quality of Life Measure Into Polish
ARTICLE IN PRESS Adaptation and Validation of the Voice-Related Quality of Life Measure Into Polish *Ewelina Sielska-Badurek, *Anna Rzepakowska, †Maria Sobol, *Ewa Osuch-Wójcikiewicz, and *Kazimierz Niemczyk, *†Warsaw, Poland Summary: Objectives. The purpose of the study was to translate and adapt the original V-RQOL (Voice-Related Quality of Life) instrument into Polish and to evaluate the psychometric properties of the Polish version of the V-RQOL Measure such as internal consistency, reliability, and construct validity in different groups of dysphonic patients. Methods. A total of 214 patients with voice disorders were assessed using the V-RQOL Measure, the Voice Handicap Index, and the World Health Organization Quality of Life, short version. Results. The Polish version of the V-RQOL Measure showed strong internal consistency with the Cronbach alpha coefficient: 0.92 for the total score, 0.90 for the social-emotional domain, and 0.86 for the physical functioning domain, and a good test-retest reliability (r-Spearman correlation coefficient: r = 0.8852 for the total score of the V-RQOL Measure). Construct validity was demonstrated with a strong correlation to the Voice Handicap Index (r = −0.843, P = 0.000*) and a weak positive, statistically significant correlation between the V-RQOL—physical functioning domain, V-RQOL—social-emotional domain, and the Q1, Q2, and Domain 1–Domain 4 of the World Health Organization Quality of Life, short version (0.2 < r < 0.4). Conclusions. The Polish version of the V-RQOL Measure is a valid and reliable instrument to evaluate the patient’s perception of his or her own voice disorders and the impact it can have on the patient’s life. The V-RQOL Measure is easy to perform in clinical practice. Key Words: Voice-Related Quality of Life (V-RQOL) Measure–Validation–Voice disorders–Voice Handicap Index (VHI)–Quality of life.
INTRODUCTION The Voice-Related Quality of Life (V-RQOL) Measure was established as a reliable and valid instrument in the assessment of patients with voice disorders and their treatment outcomes.1 A study from 2005 determined that the V-RQOL Measure and the Voice Handicap Index (VHI)2, instruments designed for evaluating voice disorders, had the most complete published psychometric data.3 The VHI focuses on the concept of handicap, which is defined by the World Health Organization (WHO) as “a social, economic, or environmental disadvantage resulting from an impairment or disability.”4 The V-RQOL instrument measures the impact of the voice disorder on the patient’s voice-related quality of life. WHO defines quality of life as “individual perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns.”4 The VHI was translated into Polish in 20045 and soon after was applied in clinical practice in patients with voice disorders. The VHI questionnaire is a 30-item instrument that measures the physical, functional, and emotional consequences of voice disorders. The V-RQOL Measure seems to be more useful in
Accepted for publication November 18, 2015. From the *Department of Otolaryngology, Medical University of Warsaw, Warsaw, Poland; and the †Department of Biophysics and Human Physiology, Medical University of Warsaw, Warsaw, Poland. Address correspondence and reprint requests to Anna Rzepakowska, Department of Otolaryngology, Medical University of Warsaw, Banacha 1a, 02-097 Warsaw, Poland. E-mail address: [email protected] Journal of Voice, Vol. ■■, No. ■■, pp. ■■-■■ 0892-1997 © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jvoice.2015.11.014
clinical practice, considering the lower number of questions it has in the social-emotional (SE) and physical functioning (PF) domains. The American version of the V-RQOL Measure was translated into several languages6–10 and is widely used in clinical studies.11–13 The purpose of the present study was to translate and adapt the original V-RQOL Measure into Polish and to evaluate the psychometric properties of the Polish version of the V-RQOL Measure such as internal consistency, reliability, and construct validity in different groups of dysphonic patients. MATERIALS AND METHODS Participants From April 2012 to April 2015, 214 patients from the Phoniatric Ambulatory and the Otolaryngology Department, Medical University of Warsaw, were included in the study. The inclusion requirements were patients should have voice disorders and should be at least 18 years old. All the 214 patients comprising the study group (SG) were divided into five subgroups for comparative purposes. The patients were assigned to each subgroup based on the laryngeal videostroboscopic findings and on the histopathology in cases of surgery: I—neurogenic, II—benign laryngeal lesions, III—chronic laryngitis, IV—functional, and V—malignant lesions. In the control group (CG), there were 32 participants who did not report any history of voice disorders. They were recruited from the staff of the Medical University of Warsaw and from the group of patients with otologic disorders. The study was approved by the Ethics Committee at Medical University of Warsaw. Table 1 shows the demographic characteristics.
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TABLE 1. Demographic Characteristics n Group SG I II III IV V CG
Age (years) Number
Male
Female
Mean ± SD
Median
Range
214 12 87 46 46 23 32
65 4 14 14 12 21 12
149 8 73 32 34 2 20
52.2 ± 13.6 55.2 ± -9.5 48.7 ± 12.6 57.1 ± 10.9 47.9 ± 16.2 62.6 ± 9.2 43.3 ± 11.4
54.5 55.5 51 57.5 49 59 42
19–85 38–70 19–69 36–81 19–73 45–85 27–63
Abbreviations: I, neurogenic; II, benign laryngeal lesions; III, chronic laryngitis; IV, functional; V, malignant lesions; CG, control group; SG, study group.
V-RQOL Measure The American version of the V-RQOL Measure was translated into Polish by the first two authors and later consulted with and corrected by a professional English translator (Appendix). The questionnaire contains 10 items in two domains: PF (items 1, 2, 3, 6, 7, and 9) and SE (items 4, 5, 8, and 10). Each item is graded on a five-point Likert scale. The overall score and the two domains’ scores range from 0 to 100, where 0 indicates a very poor V-RQOL and 100 indicates a very good V-RQOL. The scores are calculated from an algorithm proposed by the authors of the V-RQOL Measure.1
any change of their voice after the first assessment and 28 subjects without any history of voice disorders were asked to fill in the questionnaires at home in 2 weeks’ time and send it back or bring it to the department in an enclosed envelope.
World Health Organization Quality of Life, short version (WHOQOL-BREF) The WHOQOL-BREF is a 26-item version that is an abbreviation of the WHOQOL-100 that is widely used in clinical practice in Poland. The WHOQOL-BREF questionnaire begins with two items (Q1 and Q2) concerning, respectively, the individual’s overall perception of life quality, and the overall perception of the individual’s health. The remaining 24 items of the WHOQOLBREF are constructed to create four main domains: physical (Domain 1), social (Domain 2), relationships (Domain 3), and environmental (Domain 4). Each domain and the first two items are scored individually. The score of each domain is scaled in a positive direction with higher scores indicating a higher quality of life.
Statistical analysis A statistical analysis was performed using the Statistical12 package (StatSoft Poland, Dell Statistica Partner). The chi-square test was used to assess the relationship between gender and type of diagnosis. The Fischer exact test was used when the expected cell counts were less than 5. The results were considered as statistically significant if the P value was less than 0.05 (P < 0.05). The reliability of the V-RQOL Measure was determined by examined internal consistency and test-retest reliability. Internal consistency of the V-RQOL Measure was evaluated using the Cronbach alpha coefficient. The number of samples available for the test-retest reliability analysis was determined using the r-Spearman coefficient. Nonparametric Kruskal-Wallis test was used to compare the scores of the V-RQOL Measure in five subgroups with voice disorders with that of the CG. To assess the differences between the five subgroups with voice disorders and the CG (discriminant validity), the nonparametric Mann-Whitney U test was performed. Because of multiple comparisons, the Bonferroni correction was included. The results were considered as statistically significant if the P value was less than 0.05 (P < 0.05), or 0.01 (P < 0.01) in the case of multiple comparisons. The evaluated criterion-related validity, correlations between V-RQOL Measure overall score, V-RQOL—PF, V-RQOL—SE, VHI total score, VHI I–III, and WHOQOL Q1, Q2, Domain 1–Domain 4 were assessed using Pearson product-moment correlation. The results were assumed as statistically significant if P < 0.05.
Procedure Patients with voice disorders who reported to the Phoniatric Ambulatory and the Otolaryngology Department, Medical University of Warsaw, were asked to participate in the study. After a short explanation by the examiner, participants filled in the questionnaires on the same day without later help; 23 participants who did not undergo surgery or any other treatment and did not notice
RESULTS Table 2 shows the mean value, standard deviation, and range of overall V-RQOL, V-RQOL—PF, and V-RQOL—SE Measure scores of the SG and the CG. To compare categorical variables such as gender and diagnosis, the chi-square test was applied. The P value yielded 0.003, showing a significant difference between gender and diagnosis.
VHI VHI contains 30 items, which are distributed in three 10-item subscales: functional (VHI I), physical (VHI II), and emotional (VHI III). Each item is graded on a five-point Likert scale. The overall score ranges from 0 to 120, where 0 indicates no complaints and 120 represents unbearable discomfort.
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Adaptation and Validation of the V-RQOL Into Polish
TABLE 2. Value of Total and Domain V-RQOL for Patients in the Study Group and the Control Group V-RQOL
PF
SE
Group
Mean ± SD
Median
Range
Mean ± SD
Median
Range
Mean ± SD
Median
Range
SG I II III IV V CG
75.7 ± 20.3 65.4 ± 27.8 76.9 ± 20.1 79.0 ± 22.4 71.5 ± 16.8 78.0 ± 17.4 97.9 ± 5.2
80 70 80 85 73.8 80 100
15–100 17.5–100 15–100 20–100 20–100 45–100 75–100
72.2 ± 21.3 60.8 ± 30.1 73.3 ± 20.2 75.6 ± 23.1 68.8 ± 19.5 75.0 ± 18.5 97.3 ± 6.9
75 64.6 79.2 83.3 70.8 75 100
4.2–100 4.2–100 16.7–100 29.2–100 29.2–100 41.7–100 70.8–100
81.0 ± 23.4 69.8 ± 33.3 82.3 ± 23.5 83.8 ± 24.7 79.2 ± 20.5 80.2 ± 19.4 99.0 ± 6.9
87.5 81.3 87.5 100 81.3 87.5 100
6.3–100 6.3–100 6.3–100 6.3–100 6.3–100 43.8–100 81.3–100
Abbreviations: PF, physical functional items of V-RQOL; SE, social-emotional items of V-RQOL.
Internal consistency Internal consistency of the V-RQOL Measure was determined using the Cronbach alpha coefficient. The measurement of the internal consistency showed a very high Cronbach alpha coefficient for the total V-RQOL instrument score, which was found to be 0.92: 0.90 for the SE domain, and 0.86 for the PF domain. A more detailed analysis of each question indicates that all of the items have similar influence on the reliability of the whole scale. Table 3 presents the Cronbach alpha coefficient for items 1–10 (0.901–0.908). Strong Cronbach alpha coefficient, as in the study, indicates that the items are measuring the same construct. Test-retest reliability To measure test-retest reliability, the V-RQOL instrument was completed and sent or brought back by the 32 participants (seven from the SG and 25 from the CG) twice within a 2- to 4-week interval (19 participants did not complete the questionnaire for the second time). The median and the range of the V-RQOL Measure for the first assessment was 100 (72.5–100), whereas the median and the range of the V-RQOL Measure for the second assessment was 98.8 (52.5–100). To measure the test-retest reliability, the Spearman test was used. The r-Spearman correlation coefficient was r = 0.8852 for the total score of the V-RQOL instrument. This indicates that there is a good level of reproducibility.
TABLE 3. V-RQOL Measure Reliability Analysis, Internal Consistency (Evaluated by Cronbach Alpha), and Stability (Evaluated by Pearson r) Item (No.) 1 2 3 4 5 6 7 8 9 10
Cronbach Alpha
Pearson r
0.909 0.910 0.908 0.902 0.903 0.905 0.917 0.904 0.901 0.908
0.657 0.625 0.669 0.769 0.752 0.713 0.522 0.747 0.780 0.692
Construct validity analysis (discriminant validity) The results of the Kruskal-Wallis analysis of variance for V-RQOL, V-RQOL—PF, and V-RQOL—SE Measure showed a statistically significant difference for the considered subgroups, P = 0.000* (P < 0.001) (Figure 1). The differences in multiple comparisons (between the CG and the patients from groups I–V) for V-RQOL, V-RQOL—PF, and V-RQOL—SE Measure were analysed using a nonparametric Mann-Whitney U test followed by the Bonferroni correction. The results were considered statistically significant when the P value was less than 0.01. The results are presented in Table 4. Significant differences were found between the CG and the five subgroups. The median and the range for all considered groups are given in Table 2. Correlations (criterion-related validity) The results of the r-Pearson product-moment correlation test showed a strong negative statistically significant correlation between the V-RQOL Measure and the VHI total, VHI I–III. The strong negative correlation between the VHI and the V-RQOL instrument is presented in Figure 2 (r = −0.843, P = 0.000*). The correlation between the V-RQOL Measure and the VHI I–III (respectively r = −0.784, r = −0.702, r = −0.807) is not as strong but still significant. Moreover, we noticed a weak positive, statistically significant correlation between the V-RQOL—PF, V-RQOL—SE Measure, and the Q1, Q2, and Domain 1–Domain 4 of the WHOQOL-BREF (0.2 < r < 0.4). DISCUSSION This study showed that the Polish version of the V-RQOL Measure has a good internal consistency and is a reliable and valid instrument for assessment of patients with voice disorders. These findings are consistent with similar studies.6–9 The V-RQOL instrument is easy to perform in clinical practice and as we noticed, most of our patients were able to complete the questionnaire within 5 minutes, correspondingly as reported by Hogikyan and Sethuraman.1 The obtained value of the Cronbach alpha coefficient was 0.92 for the total V-RQOL Measure score, which corresponds to the results of similar research in other languages: 0.89,1 0.96,6 0.93,7 0.91,8–10 0.9,8 and 0.92.8
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FIGURE 1. Box-whisker plot of the distributions of V-RQOL in the control group and I–V subgroups. I, neurogenic voice disorders; II, benign laryngeal lesions; III, chronic laryngitis; IV, functional voice disorders; V, malignant lesions; CG, control group.
Similar to previous studies,9,10 the value of r-Pearson correlation coefficient indicates a strong correlation between the V-RQOL Measure and the VHI. Further analysis revealed a weak positive, statistically significant correlation between the V-RQOL—PF and the V-RQOL—SE Measure, and the WHOQOL-BREF (Q1, Q2, and Domain 1–Domain 4). The results show that both the V-RQOL Measure and the VHI evaluate the same concept: quality of life in patients with voice disorders. The total mean V-RQOL Measure score in our SG was similar (75.7) with the results obtained by Behlau et al (75.1)6 and by Aaby and Heimdal (74.5),9 and was higher than in other studies: 53.5,1 61.37, or 51.2.10 Aaby and Heimdal explained their results by different material (SG with more than one-third of the patients with laryngeal cancer for whom voice quality may be perceived as a secondary problem). In our study, majority were TABLE 4. Results of Mann-Whitney U Test Between the Control Group and Groups I–V
CG vs. I CG vs. II CG vs. III CG vs. IV CG vs. V
V-RQOL
PF
SE
0.000* 0.000* 0.000* 0.000* 0.000*
0.000* 0.000* 0.000* 0.000* 0.000*
0.000* 0.000* 0.000* 0.000* 0.000*
* Statistically significant (Bonferroni correlation significance level was set at P = 0.01).
patients with benign laryngeal lesions and chronic laryngitis. Patients with laryngeal cancer constituted about 10% of the SG. The obtained results may be related to the character of the hospital (public medical center) in which patients can allow themselves to wait longer for a diagnostic process or surgery than in private hospitals. The total score of the Polish version of the V-RQOL Measure was the lowest in patients with neurogenic voice disorders. Similar results were obtained by Moradi et al.10 Authors suggested that the total score of the V-RQOL Measure might be influenced by the etiology of voice disorders.10 Patients with neurogenic voice disorders require long treatment with very often-unpredictable effects. Surgery and voice rehabilitation in a group of patients with benign laryngeal lesions in most cases result in significant voice improvement. In our study, similar to the study conducted by Aaby and Heimdal,9 the mean score of the V-RQOL Measure in patients with laryngeal cancer was higher than in subjects from other subgroups. A further study should be performed to check the application of the Polish version of the V-RQOL Measure and its responsiveness to change. CONCLUSION Based on the result, the Polish version of the V-RQOL Measure is a valid and reliable instrument that evaluates the patient’s perception of voice disorders and the impact it has on the patient’s life. The V-RQOL instrument is easy to perform in clinical practice.
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Adaptation and Validation of the V-RQOL Into Polish
FIGURE 2. Scatter plot showing the correlation between the V-RQOL and the VHI scores. APPENDIX V-RQOL—Polish Version Imie˛ i Nazwisko. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . Voice-Related Quality of Life (V-RQOL)
Data. . .. . .. . .. . .. . .. . .
1 = nigdy nie mam z tym problemu 2 = mały problem 3 = umiarkowany problem 4 = duz˙y problem 5 = juz˙ gorzej byc´ nie moz˙e Z powodu mojego głosu: Jaki to stanowi dla mnie problem? 1
2
3
4
5
1. Mam trudnos´ci z głos´nym mówieniem / jestem słabo słyszalna/-y w głos´nym otoczeniu 2. Brakuje mi powietrza przy mówieniu i musze˛ je cze˛sto dobierac´ 3. Czasami nie wiem co sie˛ wydarzy, gdy zaczynam mówic´ 4. Czasami jestem niespokojna/-y i sfrustrowana/-y 5. Czasami jestem przygne˛biona/-y 6. Mam kłopoty z uz˙ywaniem telefonu 7. Mam kłopoty z praca˛ lub z wykonywaniem mojego zawodu 8. Unikam kontaktów towarzyskich 9. Musze˛ powtarzac´, aby byc´ zrozumiana˛ /-ym 10. Coraz mniej wychodze˛ z domu
REFERENCES 1. Hogikyan ND, Sethuraman G. Validation of an instrument to measure voice-related quality of life (V-RQOL). J Voice. 1999;13:557–569. 2. Jacobson BH, Johnson A, Grywalski C, et al. The voice handicap index (VHI), development and validation. Am JSL Pathol. 1997;6: 66–70. 3. Franic DM, Bramlett RE, Bothe AC. Psychometric evaluation of disease specific quality of life instruments in voice disorders. J Voice. 2005;19:300– 315.
4. World Health Organization. The World Health Organization Quality of Life instruments. Measuring the Quality of Life. WHO/MSA/MNH/PSF;1997:1– 15. 5. Pruszewicz A, Obre˛bowski A, Wiskirska-Woz´nica B, et al. Complex voice assessment—Polish version of the voice handicap index (VHI). Otolaryngol Pol. 2004;58:547–549. 6. Behlau M, Hogikyan ND, Gasparin G. Quality of life and voice: study of a Brazilian population using the voice-related quality of life measure. Folia Phoniatr Logop. 2007;59:286–296.
ARTICLE IN PRESS 6 7. Schwanfelder C, Eysholdt U, Rosanowski F, et al. Voice-related quality of life: structure, validity and factors of the German questionnaire. Folia Phoniatr Logop. 2008;60:241–248. 8. Deshpande MS, Kakade AC, Chaukar DA, et al. Validation and assessment of voice- related quality of life in Indian patients undergoing total laryngectomy and primary tracheoesophageal puncture. Head Neck. 2009;31:37–44. 9. Aaby C, Heimdal JH. The voice-related quality of life (V-RQOL) measure—a study on validity and reliability of the Norwegian version. J Voice. 2013;27:258, e29-258.e33. 10. Moradi N, Saki N, Aghadoost O, et al. Cross-cultural adaptation and validation of the voice-related quality of life into Persian. J Voice. 2014;28:842, e1-842.e9.
Journal of Voice, Vol. ■■, No. ■■, 2015 11. Hogikyan ND, Wodchis WP, Terelle JE, et al. Voice-related quality of life (V-RQOL) following type I thyreoplasty for unilateral vocal fold paralysis. J Voice. 2000;14:378–386. 12. Hogikyan ND, Wodchis WP, Spac C, et al. Longitudinal effects of botulin toxin injections on voice-related quality of life (V-RQOL) for patients with adductory spasmodic dysphonia. J Voice. 2001;15:576–586. 13. Rasch T, Gunther S, Hoppe U, et al. Voice-related quality of life in organic and functional voice disorders. Logoped Phoniatr Vocol. 2005;30:9–13.
INTRODUCTION The Voice-Related Quality of Life (V-RQOL) Measure was established as a reliable and valid instrument in the assessment of patients with voice disorders and their treatment outcomes.1 A study from 2005 determined that the V-RQOL Measure and the Voice Handicap Index (VHI)2, instruments designed for evaluating voice disorders, had the most complete published psychometric data.3 The VHI focuses on the concept of handicap, which is defined by the World Health Organization (WHO) as “a social, economic, or environmental disadvantage resulting from an impairment or disability.”4 The V-RQOL instrument measures the impact of the voice disorder on the patient’s voice-related quality of life. WHO defines quality of life as “individual perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns.”4 The VHI was translated into Polish in 20045 and soon after was applied in clinical practice in patients with voice disorders. The VHI questionnaire is a 30-item instrument that measures the physical, functional, and emotional consequences of voice disorders. The V-RQOL Measure seems to be more useful in
Accepted for publication November 18, 2015. From the *Department of Otolaryngology, Medical University of Warsaw, Warsaw, Poland; and the †Department of Biophysics and Human Physiology, Medical University of Warsaw, Warsaw, Poland. Address correspondence and reprint requests to Anna Rzepakowska, Department of Otolaryngology, Medical University of Warsaw, Banacha 1a, 02-097 Warsaw, Poland. E-mail address: [email protected] Journal of Voice, Vol. ■■, No. ■■, pp. ■■-■■ 0892-1997 © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jvoice.2015.11.014
clinical practice, considering the lower number of questions it has in the social-emotional (SE) and physical functioning (PF) domains. The American version of the V-RQOL Measure was translated into several languages6–10 and is widely used in clinical studies.11–13 The purpose of the present study was to translate and adapt the original V-RQOL Measure into Polish and to evaluate the psychometric properties of the Polish version of the V-RQOL Measure such as internal consistency, reliability, and construct validity in different groups of dysphonic patients. MATERIALS AND METHODS Participants From April 2012 to April 2015, 214 patients from the Phoniatric Ambulatory and the Otolaryngology Department, Medical University of Warsaw, were included in the study. The inclusion requirements were patients should have voice disorders and should be at least 18 years old. All the 214 patients comprising the study group (SG) were divided into five subgroups for comparative purposes. The patients were assigned to each subgroup based on the laryngeal videostroboscopic findings and on the histopathology in cases of surgery: I—neurogenic, II—benign laryngeal lesions, III—chronic laryngitis, IV—functional, and V—malignant lesions. In the control group (CG), there were 32 participants who did not report any history of voice disorders. They were recruited from the staff of the Medical University of Warsaw and from the group of patients with otologic disorders. The study was approved by the Ethics Committee at Medical University of Warsaw. Table 1 shows the demographic characteristics.
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TABLE 1. Demographic Characteristics n Group SG I II III IV V CG
Age (years) Number
Male
Female
Mean ± SD
Median
Range
214 12 87 46 46 23 32
65 4 14 14 12 21 12
149 8 73 32 34 2 20
52.2 ± 13.6 55.2 ± -9.5 48.7 ± 12.6 57.1 ± 10.9 47.9 ± 16.2 62.6 ± 9.2 43.3 ± 11.4
54.5 55.5 51 57.5 49 59 42
19–85 38–70 19–69 36–81 19–73 45–85 27–63
Abbreviations: I, neurogenic; II, benign laryngeal lesions; III, chronic laryngitis; IV, functional; V, malignant lesions; CG, control group; SG, study group.
V-RQOL Measure The American version of the V-RQOL Measure was translated into Polish by the first two authors and later consulted with and corrected by a professional English translator (Appendix). The questionnaire contains 10 items in two domains: PF (items 1, 2, 3, 6, 7, and 9) and SE (items 4, 5, 8, and 10). Each item is graded on a five-point Likert scale. The overall score and the two domains’ scores range from 0 to 100, where 0 indicates a very poor V-RQOL and 100 indicates a very good V-RQOL. The scores are calculated from an algorithm proposed by the authors of the V-RQOL Measure.1
any change of their voice after the first assessment and 28 subjects without any history of voice disorders were asked to fill in the questionnaires at home in 2 weeks’ time and send it back or bring it to the department in an enclosed envelope.
World Health Organization Quality of Life, short version (WHOQOL-BREF) The WHOQOL-BREF is a 26-item version that is an abbreviation of the WHOQOL-100 that is widely used in clinical practice in Poland. The WHOQOL-BREF questionnaire begins with two items (Q1 and Q2) concerning, respectively, the individual’s overall perception of life quality, and the overall perception of the individual’s health. The remaining 24 items of the WHOQOLBREF are constructed to create four main domains: physical (Domain 1), social (Domain 2), relationships (Domain 3), and environmental (Domain 4). Each domain and the first two items are scored individually. The score of each domain is scaled in a positive direction with higher scores indicating a higher quality of life.
Statistical analysis A statistical analysis was performed using the Statistical12 package (StatSoft Poland, Dell Statistica Partner). The chi-square test was used to assess the relationship between gender and type of diagnosis. The Fischer exact test was used when the expected cell counts were less than 5. The results were considered as statistically significant if the P value was less than 0.05 (P < 0.05). The reliability of the V-RQOL Measure was determined by examined internal consistency and test-retest reliability. Internal consistency of the V-RQOL Measure was evaluated using the Cronbach alpha coefficient. The number of samples available for the test-retest reliability analysis was determined using the r-Spearman coefficient. Nonparametric Kruskal-Wallis test was used to compare the scores of the V-RQOL Measure in five subgroups with voice disorders with that of the CG. To assess the differences between the five subgroups with voice disorders and the CG (discriminant validity), the nonparametric Mann-Whitney U test was performed. Because of multiple comparisons, the Bonferroni correction was included. The results were considered as statistically significant if the P value was less than 0.05 (P < 0.05), or 0.01 (P < 0.01) in the case of multiple comparisons. The evaluated criterion-related validity, correlations between V-RQOL Measure overall score, V-RQOL—PF, V-RQOL—SE, VHI total score, VHI I–III, and WHOQOL Q1, Q2, Domain 1–Domain 4 were assessed using Pearson product-moment correlation. The results were assumed as statistically significant if P < 0.05.
Procedure Patients with voice disorders who reported to the Phoniatric Ambulatory and the Otolaryngology Department, Medical University of Warsaw, were asked to participate in the study. After a short explanation by the examiner, participants filled in the questionnaires on the same day without later help; 23 participants who did not undergo surgery or any other treatment and did not notice
RESULTS Table 2 shows the mean value, standard deviation, and range of overall V-RQOL, V-RQOL—PF, and V-RQOL—SE Measure scores of the SG and the CG. To compare categorical variables such as gender and diagnosis, the chi-square test was applied. The P value yielded 0.003, showing a significant difference between gender and diagnosis.
VHI VHI contains 30 items, which are distributed in three 10-item subscales: functional (VHI I), physical (VHI II), and emotional (VHI III). Each item is graded on a five-point Likert scale. The overall score ranges from 0 to 120, where 0 indicates no complaints and 120 represents unbearable discomfort.
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Adaptation and Validation of the V-RQOL Into Polish
TABLE 2. Value of Total and Domain V-RQOL for Patients in the Study Group and the Control Group V-RQOL
PF
SE
Group
Mean ± SD
Median
Range
Mean ± SD
Median
Range
Mean ± SD
Median
Range
SG I II III IV V CG
75.7 ± 20.3 65.4 ± 27.8 76.9 ± 20.1 79.0 ± 22.4 71.5 ± 16.8 78.0 ± 17.4 97.9 ± 5.2
80 70 80 85 73.8 80 100
15–100 17.5–100 15–100 20–100 20–100 45–100 75–100
72.2 ± 21.3 60.8 ± 30.1 73.3 ± 20.2 75.6 ± 23.1 68.8 ± 19.5 75.0 ± 18.5 97.3 ± 6.9
75 64.6 79.2 83.3 70.8 75 100
4.2–100 4.2–100 16.7–100 29.2–100 29.2–100 41.7–100 70.8–100
81.0 ± 23.4 69.8 ± 33.3 82.3 ± 23.5 83.8 ± 24.7 79.2 ± 20.5 80.2 ± 19.4 99.0 ± 6.9
87.5 81.3 87.5 100 81.3 87.5 100
6.3–100 6.3–100 6.3–100 6.3–100 6.3–100 43.8–100 81.3–100
Abbreviations: PF, physical functional items of V-RQOL; SE, social-emotional items of V-RQOL.
Internal consistency Internal consistency of the V-RQOL Measure was determined using the Cronbach alpha coefficient. The measurement of the internal consistency showed a very high Cronbach alpha coefficient for the total V-RQOL instrument score, which was found to be 0.92: 0.90 for the SE domain, and 0.86 for the PF domain. A more detailed analysis of each question indicates that all of the items have similar influence on the reliability of the whole scale. Table 3 presents the Cronbach alpha coefficient for items 1–10 (0.901–0.908). Strong Cronbach alpha coefficient, as in the study, indicates that the items are measuring the same construct. Test-retest reliability To measure test-retest reliability, the V-RQOL instrument was completed and sent or brought back by the 32 participants (seven from the SG and 25 from the CG) twice within a 2- to 4-week interval (19 participants did not complete the questionnaire for the second time). The median and the range of the V-RQOL Measure for the first assessment was 100 (72.5–100), whereas the median and the range of the V-RQOL Measure for the second assessment was 98.8 (52.5–100). To measure the test-retest reliability, the Spearman test was used. The r-Spearman correlation coefficient was r = 0.8852 for the total score of the V-RQOL instrument. This indicates that there is a good level of reproducibility.
TABLE 3. V-RQOL Measure Reliability Analysis, Internal Consistency (Evaluated by Cronbach Alpha), and Stability (Evaluated by Pearson r) Item (No.) 1 2 3 4 5 6 7 8 9 10
Cronbach Alpha
Pearson r
0.909 0.910 0.908 0.902 0.903 0.905 0.917 0.904 0.901 0.908
0.657 0.625 0.669 0.769 0.752 0.713 0.522 0.747 0.780 0.692
Construct validity analysis (discriminant validity) The results of the Kruskal-Wallis analysis of variance for V-RQOL, V-RQOL—PF, and V-RQOL—SE Measure showed a statistically significant difference for the considered subgroups, P = 0.000* (P < 0.001) (Figure 1). The differences in multiple comparisons (between the CG and the patients from groups I–V) for V-RQOL, V-RQOL—PF, and V-RQOL—SE Measure were analysed using a nonparametric Mann-Whitney U test followed by the Bonferroni correction. The results were considered statistically significant when the P value was less than 0.01. The results are presented in Table 4. Significant differences were found between the CG and the five subgroups. The median and the range for all considered groups are given in Table 2. Correlations (criterion-related validity) The results of the r-Pearson product-moment correlation test showed a strong negative statistically significant correlation between the V-RQOL Measure and the VHI total, VHI I–III. The strong negative correlation between the VHI and the V-RQOL instrument is presented in Figure 2 (r = −0.843, P = 0.000*). The correlation between the V-RQOL Measure and the VHI I–III (respectively r = −0.784, r = −0.702, r = −0.807) is not as strong but still significant. Moreover, we noticed a weak positive, statistically significant correlation between the V-RQOL—PF, V-RQOL—SE Measure, and the Q1, Q2, and Domain 1–Domain 4 of the WHOQOL-BREF (0.2 < r < 0.4). DISCUSSION This study showed that the Polish version of the V-RQOL Measure has a good internal consistency and is a reliable and valid instrument for assessment of patients with voice disorders. These findings are consistent with similar studies.6–9 The V-RQOL instrument is easy to perform in clinical practice and as we noticed, most of our patients were able to complete the questionnaire within 5 minutes, correspondingly as reported by Hogikyan and Sethuraman.1 The obtained value of the Cronbach alpha coefficient was 0.92 for the total V-RQOL Measure score, which corresponds to the results of similar research in other languages: 0.89,1 0.96,6 0.93,7 0.91,8–10 0.9,8 and 0.92.8
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FIGURE 1. Box-whisker plot of the distributions of V-RQOL in the control group and I–V subgroups. I, neurogenic voice disorders; II, benign laryngeal lesions; III, chronic laryngitis; IV, functional voice disorders; V, malignant lesions; CG, control group.
Similar to previous studies,9,10 the value of r-Pearson correlation coefficient indicates a strong correlation between the V-RQOL Measure and the VHI. Further analysis revealed a weak positive, statistically significant correlation between the V-RQOL—PF and the V-RQOL—SE Measure, and the WHOQOL-BREF (Q1, Q2, and Domain 1–Domain 4). The results show that both the V-RQOL Measure and the VHI evaluate the same concept: quality of life in patients with voice disorders. The total mean V-RQOL Measure score in our SG was similar (75.7) with the results obtained by Behlau et al (75.1)6 and by Aaby and Heimdal (74.5),9 and was higher than in other studies: 53.5,1 61.37, or 51.2.10 Aaby and Heimdal explained their results by different material (SG with more than one-third of the patients with laryngeal cancer for whom voice quality may be perceived as a secondary problem). In our study, majority were TABLE 4. Results of Mann-Whitney U Test Between the Control Group and Groups I–V
CG vs. I CG vs. II CG vs. III CG vs. IV CG vs. V
V-RQOL
PF
SE
0.000* 0.000* 0.000* 0.000* 0.000*
0.000* 0.000* 0.000* 0.000* 0.000*
0.000* 0.000* 0.000* 0.000* 0.000*
* Statistically significant (Bonferroni correlation significance level was set at P = 0.01).
patients with benign laryngeal lesions and chronic laryngitis. Patients with laryngeal cancer constituted about 10% of the SG. The obtained results may be related to the character of the hospital (public medical center) in which patients can allow themselves to wait longer for a diagnostic process or surgery than in private hospitals. The total score of the Polish version of the V-RQOL Measure was the lowest in patients with neurogenic voice disorders. Similar results were obtained by Moradi et al.10 Authors suggested that the total score of the V-RQOL Measure might be influenced by the etiology of voice disorders.10 Patients with neurogenic voice disorders require long treatment with very often-unpredictable effects. Surgery and voice rehabilitation in a group of patients with benign laryngeal lesions in most cases result in significant voice improvement. In our study, similar to the study conducted by Aaby and Heimdal,9 the mean score of the V-RQOL Measure in patients with laryngeal cancer was higher than in subjects from other subgroups. A further study should be performed to check the application of the Polish version of the V-RQOL Measure and its responsiveness to change. CONCLUSION Based on the result, the Polish version of the V-RQOL Measure is a valid and reliable instrument that evaluates the patient’s perception of voice disorders and the impact it has on the patient’s life. The V-RQOL instrument is easy to perform in clinical practice.
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Adaptation and Validation of the V-RQOL Into Polish
FIGURE 2. Scatter plot showing the correlation between the V-RQOL and the VHI scores. APPENDIX V-RQOL—Polish Version Imie˛ i Nazwisko. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . Voice-Related Quality of Life (V-RQOL)
Data. . .. . .. . .. . .. . .. . .
1 = nigdy nie mam z tym problemu 2 = mały problem 3 = umiarkowany problem 4 = duz˙y problem 5 = juz˙ gorzej byc´ nie moz˙e Z powodu mojego głosu: Jaki to stanowi dla mnie problem? 1
2
3
4
5
1. Mam trudnos´ci z głos´nym mówieniem / jestem słabo słyszalna/-y w głos´nym otoczeniu 2. Brakuje mi powietrza przy mówieniu i musze˛ je cze˛sto dobierac´ 3. Czasami nie wiem co sie˛ wydarzy, gdy zaczynam mówic´ 4. Czasami jestem niespokojna/-y i sfrustrowana/-y 5. Czasami jestem przygne˛biona/-y 6. Mam kłopoty z uz˙ywaniem telefonu 7. Mam kłopoty z praca˛ lub z wykonywaniem mojego zawodu 8. Unikam kontaktów towarzyskich 9. Musze˛ powtarzac´, aby byc´ zrozumiana˛ /-ym 10. Coraz mniej wychodze˛ z domu
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4. World Health Organization. The World Health Organization Quality of Life instruments. Measuring the Quality of Life. WHO/MSA/MNH/PSF;1997:1– 15. 5. Pruszewicz A, Obre˛bowski A, Wiskirska-Woz´nica B, et al. Complex voice assessment—Polish version of the voice handicap index (VHI). Otolaryngol Pol. 2004;58:547–549. 6. Behlau M, Hogikyan ND, Gasparin G. Quality of life and voice: study of a Brazilian population using the voice-related quality of life measure. Folia Phoniatr Logop. 2007;59:286–296.
ARTICLE IN PRESS 6 7. Schwanfelder C, Eysholdt U, Rosanowski F, et al. Voice-related quality of life: structure, validity and factors of the German questionnaire. Folia Phoniatr Logop. 2008;60:241–248. 8. Deshpande MS, Kakade AC, Chaukar DA, et al. Validation and assessment of voice- related quality of life in Indian patients undergoing total laryngectomy and primary tracheoesophageal puncture. Head Neck. 2009;31:37–44. 9. Aaby C, Heimdal JH. The voice-related quality of life (V-RQOL) measure—a study on validity and reliability of the Norwegian version. J Voice. 2013;27:258, e29-258.e33. 10. Moradi N, Saki N, Aghadoost O, et al. Cross-cultural adaptation and validation of the voice-related quality of life into Persian. J Voice. 2014;28:842, e1-842.e9.
Journal of Voice, Vol. ■■, No. ■■, 2015 11. Hogikyan ND, Wodchis WP, Terelle JE, et al. Voice-related quality of life (V-RQOL) following type I thyreoplasty for unilateral vocal fold paralysis. J Voice. 2000;14:378–386. 12. Hogikyan ND, Wodchis WP, Spac C, et al. Longitudinal effects of botulin toxin injections on voice-related quality of life (V-RQOL) for patients with adductory spasmodic dysphonia. J Voice. 2001;15:576–586. 13. Rasch T, Gunther S, Hoppe U, et al. Voice-related quality of life in organic and functional voice disorders. Logoped Phoniatr Vocol. 2005;30:9–13.