Qual Life Res (2015) 24:2789–2794 DOI 10.1007/s11136-015-1003-x

BRIEF COMMUNICATION

Turkish version of the Johns Hopkins Restless Legs Syndrome Quality of Life Questionnaire (RLS-QoL): validity and reliability study Sibel Gu¨ler1 • F. Nesrin Turan2

Accepted: 24 April 2015 / Published online: 22 May 2015 Ó Springer International Publishing Switzerland 2015

Abstract Background and purpose Restless legs syndrome (RLS), as well as problems secondary to RLS, may worsen the quality of life. Our aim was to modify the Restless Legs Syndrome Quality of Life (RLS-QoL) questionnaire advanced by Abetz (Health Qual Life Outcomes 3:79, 2005) and to analyse the validity and reliability of the questionnaire. Methods Two hundred and one consecutive patients with RLS and forty-three control subjects were included in the study. Permission regarding the translation and validation of the RLS-QoL questionnaire was obtained. The translation was conducted according to the guidelines provided by the publisher. Results For the RLS subjects, the mean Insomnia Severity Index (ISI) score, the International Restless Legs Syndrome Severity Rating Scale (IRLSSG) score and the computed score of the RLS-QoL questionnaire were 22.60 ± 3.39, 24.83 ± 5.28 and 45.93 ± 17.62, respectively. Among the RLS subjects without insomnia, the mean (±standard deviation) ISI score, IRLSSG score and computed score of the RLS-QoL questionnaire were 6.67 ± 2.34, 15.11 ± 4.03 and 41.93 ± 16.12, respectively. A significant difference was identified between both groups on all scores (ISI: p = 0.001, RLS: p = 0.001). The groups with and without insomnia were similar regarding & Sibel Gu¨ler [email protected] F. Nesrin Turan [email protected] 1

Department of Neurology, Faculty of Medicine, Trakya University , Edirne, Turkey

2

Department of Biostatistics, Faculty of Medicine, Trakya University, Edirne, Turkey

the computed score of the RLS-QoL questionnaire (p = 0.140). According to a correlation analysis, a significant correlation was identified between the ISI and IRLSSG or RLS-QoL scores (r = 0.513, p = 0.001 and r = -0.383, p = 0.001, respectively). Although the coefficient of correlation is significant between IRLSSG score and RLS-QoL scale score, it should not be considered as a powerful enough correlation (r = 0.190, p = 0.007). Most items also exhibited a strong correlation with each other. The internal consistency determined by Cronbach’s alpha indicated an extremely good correlation (0.975). Discussion These findings suggest the Turkish version of the RLS-QoL questionnaire is a valid and reliable tool for the assessment of the quality of life in patients with RLS. Keywords Restless legs syndrome  Restless Legs Syndrome Quality Of Life  Validation  Reliability  Insomnia Severity Index  Translation  Turkish version

Introduction Restless legs syndrome (RLS) is a movement disorder in which an individual experiences a strong urge to move the legs or other extremities while at rest; symptoms are temporarily or at least partially relieved by movement. The symptoms have a strong circadian feature; they are worse in the evening and at night and often dwindle in the morning at the end of the sleep period [1]. RLS has an extremely negative effect on the quality of life and sleep patterns of patients. RLS is an entity that can be clinically diagnosed; however, there is no specific biological marker. RLS has a high morbidity and causes a decrease in productivity, a deterioration in the quality of life, depressive mood and social isolation in certain populations [2]. Thus,

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this condition indicates the need for quality of life scales, which are specific for the disease and easy to conduct. Currently, in Turkey, there is no translated specific scale for RLS that has been investigated regarding validity and reliability. The Restless Legs Syndrome Quality of Life (RLS-QoL) questionnaire evaluates the effects of RLS on daily life, emotional status, sexual interest and business life [1]. Abetz et al. reported that the RLS-QoL is a valid, reliable and sensitive scale used to evaluate the quality of life in RLS patients [5]. This scale has been translated into many languages, such as Dutch, Finnish, French, German, Greek, Hindi, Hungarian, Italian and Japanese [3, 4]. Because the RLS-QoL is a valuable scale for the assessment of the treatment response to RLS, it is considered important to translate it into Turkish. In this study, we aimed to analyse the validity and reliability of the RLS-QoL questionnaire in patients with RLS from our Movement Disorders Outpatient Clinic, as well as participants from unpublished prevalence study who agreed to participate in the study. We aimed ensure the feasibility for Turkish society by examining the validity and reliability.

Methods Study sample The study sample comprised patients with RLS from our Movement Disorders Outpatient Clinic, as well as participants from an unpublished prevalence study who agreed to participate in the study. The participants were evaluated in the outpatient clinic of neurology at Trakya University. The study was approved by the Trakya University Faculty of Medicine Ethics Committee on March 19, 2014 with approval number 2014/41. To assess the quality of life and apply the RLS-QoL questionnaire in a Turkish population to determine the reliability and validity, 201 consecutive subjects with RLS [35 (17.4 %) men, 166 (82.6 %) women] were included who were diagnosed with the criteria proposed by the International RLS Research Group [6]. One hundred and eighty cases were necessary for the study because the number of the cases must be five or ten times more than the terms in the scale. However, 200 cases were included because of the potential for data loss; finally, 201 RLS cases were included. Seventeen (39.5 %) men and 26 (60.5 %) women, who were admitted to our outpatient clinic of neurology with different complaints, agreed to participate and met the inclusion and exclusion criteria, were selected and included in the study as the control group. The presence of insomnia in patients was identified using the International Classification of Sleep Disorders (ICSD-II) criteria [7]. The inclusion criteria for volunteers were as follows: more than

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18 years of age, capable of communication, motivated to participate, cooperative in answering questions and definitively diagnosed with RLS. Volunteers who had psychiatric diseases, myelopathy, osteoarthritis of the knee, rheumatoid arthritis that affects leg joints, Parkinson’s disease, peripheral neuropathy or radiculopathy or who experienced lower extremity surgery were excluded. Finally, the results obtained from the questionnaire were entered in a database and analysed for validity and reliability. Instruments A semi-structured interview form and the RLS-QoL questionnaire were used in data collection. The semistructured interview form includes the patients’ sociodemographic characteristics (age, gender, education and family history), disease status and examination findings. Two hundred and one RLS patients and 43 control patients were interviewed for the study. The interviews were conducted by the researcher using a face-to-face method. In the RLS determined patients, the criteria of the International Restless Legs Syndrome Severity Rating Scale (IRLSSG) Turkish version [7, 8] were administered to assess the disease severity scale. The Insomnia Severity Index—Turkish version—(ISI) by Boysan et al. [9, 10] was administered to the RLS patients who have secondary insomnia. After obtaining permission from the authors/distributors, the Turkish translation of the Restless Legs Syndrome Quality of Life (RLS-QoL) questionnaire [5] was used to determine the severity of RLS, sleep disruption and quality of life affected by RLS. Language Translation of the Questionnaire In the study of language validity, the questionnaire was translated by three professional educators first into Turkish and then into English to provide optimal results. Then, the questionnaire was controlled by experienced neurology specialists and was finalised. A pilot study in 50 of the 201 patients and 43 controls was conducted to investigate the language structure and clarity of the scale. The questionnaire was clearly understood by the participants in the pilot study. The information obtained from study was evaluated by the individuals who initially translated it, as well as the neurologists who checked the final version prior to administration. The translation ended when the equivalence between the scale adjusted to Turkish and the original English scale was identified. Content validity After the translation process was completed, to accept its integrity in Turkish, ten specialists and residents were

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asked to evaluate the scale for content validity. For the evaluation of the specialists’ opinions, the content validity index was used, and the specialists were asked to score a scale question with the scores 1–4 (1: inconvenient, 2: somewhat convenient, the subject needs to be formed, 3: quite convenient, but small changes may be necessary, 4: very convenient). Necessary changes were made according to recommendations of the specialists, and the scale was finalised. The mean score of the specialists for the whole scale was 3.73 ± 0.16. Each question’s content validity ratio was calculated and compared with the minimum content validity of Lawshe. As the result of the comparison, all questions remained in the scale [11]. Statistical analysis The analysis was performed using SPSS version 21.0 (SPSS, Inc., Chicago, IL, USA) and MedCalc version 13.0.4 (MedCalc Software, Ostend, Belgium). Descriptive statistics were calculated for the categorical and numeric variables. A Mann–Whitney U test was used to compare ages. A continuity correction test was used to test whether the difference between the groups in terms of gender was significant. A Pearson’s correlation coefficient was used to determine the correlation between the parametric items in the patients with and without insomnia, whereas a Spearman’s correlation coefficient was calculated for the quantitative data of the questionnaire. The content validity ratio (CVR) was used, which was developed by C. H. Lawshe and indicates whether an item is essential. The internal consistency reliability of the RLS-QoL was assessed by calculating the Cronbach’s alpha coefficient. The significance limit was set at p \ 0.05 for all statistics, and all hypotheses were evaluated by two-sided tests.

Results The study included 201 cases and 43 controls. In the RLS and control groups, 82.6 and 60.5 % of the subjects were female, respectively. A significant difference was identified between both groups regarding gender (p = 0.001). The mean age of the male patients was 47.14 ± 12.49 years, whereas the mean age of the female patients was 47.57 ± 13.10 years. In Table 1 Demographic features of the patients

Variable

the control group, the mean age of the men was 49.82 ± 13.62, whereas the mean age of the women was 40.77 ± 13.08. The mean age (±SD) of the RLS group was 47.50 ± 12.97 years, and the mean age of the control group was 44.35 ± 13.88 years. There was no significant difference between the patient and control groups in terms of age (p = 0.06 and p = 0.75, respectively; Table 1). In the RLS subjects, in the RLS patients with insomnia, the mean ISI score, IRLSSG score and computed score of the RLS-QoL questionnaire were 22.60 ± 3.39, 24.83 ± 5.28 and 45.93 ± 17.62, respectively. The RLS patients without insomnia had a mean ISI score, IRLSSG score and computed score of the RLS-QoL questionnaire of 6.67 ± 2.34, 15.11 ± 4.03 and 41.93 ± 16.12, respectively. A significant difference was identified between the RLS patients with and without insomnia regarding the ISI and IRLSSG scores (p = 0.001 and 0.001, respectively). The RLS patients with and without insomnia were similar in the computed score of the RLS-QoL questionnaire (p = 0.140; Table 2). The ISI score and the computed score of the RLS-QoL questionnaire were 18.08 ± 7.85 and 3.46 ± 1.40 and 44.80 ± 17.27 and 93.49 ± 9.73 in the patient and control groups, respectively. A significant difference was identified between the RLS patient and control groups using both the ISI score (p = 0.001) and the RLS-QoL questionnaire (p = 0.001; Table 3). There was a statistically significant difference in terms of gender and family history between patients with insomnia and without insomnia (p = 0.001 and p = 0.012, respectively; Table 4). Patients with insomnia exhibited no statistically significant relationship between ISI score and IRLSSG score (r = 0.015, p = 0.859). However, between RLS-QoL scores and ISI scores, there was a highly significant negative correlation (r = -0.823, p = 0.001). Although the coefficient of correlation is significant between IRLSSG score and RLS-QoL scale score, it should not be considered as a powerful enough correlation (r = 0.214, p = 0.010). In patients without insomnia, there was no significant relationship between ISI score and IRLSSG score (r = -0.003, p = 0.980). However, between RLS-QoL scale score and ISI score, there was a negative correlation of intermediate significance (r = -0.573, p = 0.001). Between RLS-QoL scale score and IRLSSG score, we observed no significant

Patients with RLS

Control group

p*

Male

Female

Male

Female

Gender

35 (17.4)

166 (82.6)

17 (39.5)

26 (60.5)

Age p**

47.14 ± 12.49 0.06

47.57 ± 13.10

49.82 ± 13.62 0.75

40.77 ± 13.08

0.001

* Continuity correction; ** Mann–Whitney U test

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Table 2 Comparisons of patients with and without insomnia regarding the ISI score, IRLSSG score and RLS-QoL score

Variable

Patients with RLS

p*

Patients with insomnia

Without insomnia

ISI score

22.60 ± 3.39

6.67 ± 2.34

0.001

IRLSSG score

24.83 ± 5.28

15.11 ± 4.03

0.001

RLS-QoL questionnaire

45.93 ± 17.62

41.93 ± 16.12

0.140

* Mann–Whitney U test

Table 3 Comparisons of the patient and control groups regarding the ISI score, IRLSSG score and RLS-QoL score Variable

Patients with RLS Control group

p*

3.46 ± 1.40

0.001

93.49 ± 9.73

0.001

ISI score

18.08 ± 7.85

IRLSSG score

22.07 ± 6.62

RLS-QoL questionnaire

44.80 ± 17.27

Table 5 Spearman’s rho correlation coefficients of the ISI, IRLSSG and RLS-QoL scores IRLSSG score Patients with insomnia ISI score IRLSSG score

* Mann–Whitney U test

RLS-QoL questionnaire

r

0.015

-0.823

p

0.859

0.001

r

0.214

p

0.010

Without insomnia

relationship (r = 0.090, p = 0.504). In all patients with RLS, there was a significant and moderate relationship between ISI score and IRLSSG scale score (r = 0.513, p = 0.001). It is considered that gender and family history may affect an intermediate correlation between ISI score and IRLSSG score, because when analysed separately, these variables have been shown to have statistically significant effect on insomnia. Between ISI score and RLS-QoL scale score, there was a significant and weakly negative correlation (r = -0.383, p = 0.001). Although the coefficient of correlation is significant between IRLSSG score and RLSQoL scale score, the correlation should not be considered as powerful enough (r = 0.190, p = 0.007; Table 5). Internal consistency of the Turkish version of the RLS-QoL questionnaire In the Turkish version of the RLS-QoL questionnaire, most items exhibited a good correlation with each other (Table 6). Other categorical items of the scale (items 11 and 12) also exhibited a good correlation with each other (Spearman’s rho = 0.702, p = 0.001). Numerical items 6, 15, 16, 17 and 18 were analysed separately as they exhibited correlations with each other (Table 7). The Turkish version exhibited good internal consistency (Cronbach’s alpha = 0.975).

ISI score IRLSSG score All RLS patients ISI score IRLSSG score

r

-0.003

-0.573

p

0.980

0.001

r

0.090

p

0.504

r

0.513

-0.383

p

0.001

0.001

r

0.190

p

0.007

Discussion A Cronbach’s alpha of at least 0.70 has been recommended if the measure is considered to be reliable; however, reliability coefficients are susceptible to the number of items within a scale [9, 12]. In our study, the Cronbach’s alpha, which is the reliability score of the Turkish translated version of the RLS-QoL, was 0.975. Vishwakarma et al. who conducted their study in India, reported that the reliability score of the RLS-QoL is 0.85. Abetz [3, 13] reported that the reliability score was 0.92. Our results are compatible with other studies in the literature [3, 4]. Therefore, an internal compliance between the different terms of the scale and the effects of RLS on quality of life,

Table 4 Comparisons of the patients with insomnia and without insomnia groups regarding the gender and family history Variable

Patients with insomnia

Without insomnia

p*

Gender M/F n (/%)

17(11.8)/127 (88.2)

18 (31.6)/39 (68.4)

0.002

Family history yes/no n (/%)

42 (29.2)/102 (70.8)

7 (12.3/50 (87.7)

0.020

* Continuity correction

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Qual Life Res (2015) 24:2789–2794 Table 6 Correlation between the categorical items of the Turkish version of the RLS-QoL*

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Items

Q1

Q2

Q3

Q4

Q5

Q7

Q8

Q9

Q10

Q13

Q1

1.000**

Q2

0.898**

1.000**

Q3

0.879**

0.878**

1.000**

Q4

0.796**

0.814**

0.792**

1.000**

Q5

0.689**

0.699**

0.704**

0.801**

1.000**

Q7

0.823**

0.809**

0.816**

0.784**

0.765**

1.000**

Q8

0.853**

0.833**

0.861**

0.817**

0.743**

0.857**

1.000**

Q9

0.811**

0.771**

0.796**

0.730**

0.696**

0.763**

0.807**

1.000**

Q10

0.882**

0.836**

0.842**

0.769**

0.684**

0.802**

0.832**

0.869**

1.000**

Q13

0.874**

0.859**

0.860**

0.794**

0.656**

0.825**

0.836**

0.820**

0.895**

1.000**

* Spearman’s rho correlation coefficient and it is significant at the 0.001 level (two tailed), ** p = 0.001

Table 7 Correlation between the numerical items of the Turkish version of the RLS-QoL Items

Q6

Q15

Q16

Q17

Q6

1.000

Q15

0.499*

Q16

0.547*

0.830*

1.000

Q17

0.293**

0.279**

0.319**

1.000

Q18

0.534*

0.710*

0.787*

0.472*

Q18

1.000

1.000

* Correlation is significant at the 0.001 level (two tailed); ** Correlation is significant at the 0.05 level (two tailed)

employment, sexual function and business life was identified. In our study, there was a strong correlation between all items of the RLS-QoL questionnaire. This condition demonstrates good internal consistency. In our study, consistent with the literature, women comprised the majority of the RLS patients [3, 14]. A significant correlation was identified between the ISI and RLS-QoL questionnaire scores. In previous studies, poor quality of life in RLS patients was associated with secondary insomnia [3, 5]. In our study, the quality of life of the RLS patients with secondary insomnia was also associated with a poorer quality of life. Nevertheless, we did not identify an important association between the IRLSSG and RLS-QoL questionnaire scores. This finding could be attributed to the difference in the duration of symptoms examined by both instruments. While the RLS-QoL questionnaire assessed the symptoms during the previous 4 weeks from the date of the interview, the IRLSSG assessed the severity of the symptoms only during the previous week. Because of the variability of RLS, both scores may differ, and evidence indicates that none of the instruments in question is a substitute for the other [3, 5, 15]. The results can be effected because the study group, which is evaluated with the RLS-QoL questionnaire and IRLSSG score, consists of middle-aged or older individuals and the majority of the volunteers are women.

In our study, we identified a moderate correlation between the ISI and IRLSSG scores. The RLS severity scores suggest that the quality of life of RLS patients with secondary insomnia can be poorly effected. However, there was an inverse correlation between the ISI and RLS-QoL questionnaire scores. Higher scores on the RLS-QoL are correlated with better quality of life, whereas higher ISI scores are associated with insomnia, which can cause a poor quality of life. RLS patients with insomnia and high ISI values may have negative effects on the quality of life compared with RLS patients without insomnia. This study had several methodological limitations. First, this questionnaire can be difficult to use in non-Turkish speaking populations. We suggest the translation of this instrument in other Turkish languages. Second, this questionnaire cannot be used in children because their level of understanding of the items may vary. Third, this study comprised a cross-sectional design. Thus, a longitudinal design could be used to assess the RLS-QoL questionnaire. Another limitation is that the study was conducted only in the neurology department; thus, it might not be representative of other departments in Turkey. Finally, the participation of patient and control group in the study was based on voluntary acceptance. This condition is also one of the limitations of our study. Scales that are tested and demonstrated to be adequate for validity and reliability provide eligible information for the physician who applies the scale. Thus, it is important to evaluate RLS, which causes significant disability in patient life and is reported to be a common cause of insomnia, with a specific evaluation scale. In addition, because the RLS-QoL questionnaire provides valuable data to assess the response to RLS treatment, it is considered to represent an important place in the clinical follow-up of patients in Turkey after the validity and reliability of the scale was analysed. In conclusion, the Turkish version of the RLS-QoL questionnaire is a valid and reliable tool for the assessment of the quality of life in patients with RLS. It is recommended

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that additional studies be conducted to implement the scale in broader populations across different group samples. Acknowledgments Restless Legs Syndrome Quality of Life (RLSQoL) questionnaire is a copyright to the MAPI Research Trust, France. After obtaining written permission, the translation was completed as per the instructions provided by the publisher [15]. Ó Allen (2005). Request for permission should be asked to MAPI Research Trust ([email protected]). Conflict of interest

None.

References 1. Abetz, L., Vallow, S. M., Kirsch, J., Allen, R. P., Washburn, T., & Earley, C. J. (2005). Validation of the Restless Legs Syndrome Quality of Life questionnaire. Value in Health, 8(2), 157–167. 2. Anand, S., Johansen, K. L., Grimes, B., Kaysen, G. A., Dalrymple, L. S., Kutner, N. G., et al. (2013). Physical activity and self-reported symptoms of insomnia, restless legs syndrome, and depression: The comprehensive dialysis study. Hemodialysis International, 17(1), 50–58. 3. Abetz, L., Arbuckle, R., Allen, R. P., Mavraki, E., & Kirsch, J. (2005). The reliability, validity and responsiveness of the Restless Legs Syndrome Quality of Life questionnaire (RLSQoL) in a trial population. Health Qual Life Outcomes, 3, 79. 4. Vishwakarma, K., Lahan, V., Gupta, R., Goel, D., Dhasmana, D. C., Sharma, T., et al. (2012). Translation and validation of restless leg syndrome quality of life questionnaire in Hindi language. Neurology India, 60(5), 476–480. 5. Available from: http://www.proqolid.org/instruments/restless_ legs_quality_of_life_scale_or_hopkins_rls_quality_of_life_scale_ rls_qol_or_hopkins_rls_qol. Last accessed on May 25, 2012.

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6. Allen, R. P., Picchietti, D., Hening, W. A., Trenkwalder, C., Walters, A. S., & Montplaisi, J. (2003). Restless legs syndrome: Diagnostic criteria, special considerations, and epidemiology. A report from the restless legs syndrome diagnosis and epidemiology work shop at the National Institutes of Health. Sleep Medicine, 4(2), 101–119. 7. American Academy of Sleep Medicine. (2005). The International Classification of Sleep Disorders: diagnostic and coding manual (2nd ed.). Westchester: American Academy of Sleep Medicine. 8. Sevim, S., Dog˘u, O., C¸amdeviren, H., Bug˘daycı, R., S¸ as¸ maz, T., Kaleag˘ası, H., et al. (2003). Unexpectedly low prevalence and unusual characteristics of RLS in Mersin, Tu¨rkey. Neurology, 61(11), 1562–1569. 9. Walters, A. S., LeBrocq, C., Dhar, A., Hening, W., Rosen, R., Allen, R. P., et al. (2003). Validation of the International Restless Legs Syndrome Study Group rating scale for restless legs syndrome. Sleep Medicine, 4(2), 121–132. 10. Boysan, M., Gu¨lec¸, M., Bes¸ irog˘lu, L., & Kalafat, T. (2010). Psychometric properties of the Insomnia Severity Index in Turkish sample. Anatolian Journal of Psychiatry, 11, 248–252. 11. Lawshe, C. H. (1975). A quantiative approach to content validity. Personel Psychology, 28, 563–575. 12. Nunnally, J. C., & Bernstein, I. H. (Eds.) (1994). The assessment of reliability. In Psychometric theory (3rd ed.). New York: McGraw-Hill College Division. 13. Atkinson, M. J., Allen, R. P., DuChane, J., Murray, C., Kushida, C., & Roth, T. (2004). Validation of the Restless Legs Syndrome Quality of Life Instrument (RLS-QLI): Findings of a consortium of national experts and the RLS Foundation. Quality of Life Research, 13(3), 679–693. 14. Sforza, E., & Haba-Rubio, J. (2005). Night-to-night variability in periodic leg movements in patients with restless legs syndrome. Sleep Medicine, 6(3), 259–267. 15. Abetz, L. (2001). Restless Legs Quality of Life Scale or Hopkins RLS Quality of Life Scale (RLS-QoL or Hopkins RLS QoL) [cited 2012 May 25].

Turkish version of the Johns Hopkins Restless Legs Syndrome Quality of Life Questionnaire (RLS-QoL): validity and reliability study.

Restless legs syndrome (RLS), as well as problems secondary to RLS, may worsen the quality of life. Our aim was to modify the Restless Legs Syndrome Q...
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