Study Population
This cross-sectional study, with a convenience sample, was conducted at the Women's Health Research Laboratory at the Federal University of São Carlos, São Carlos, SP, Brazil. Participants were 387 women with or without UI. The inclusion criteria were being over 18 years of age and literate and having at least one of the following symptoms of OAB— increased frequency, nocturia, or urgency of pollakiuria—assessed by the KHQ (cf. Instruments) [30] with the following questions: “Do you usually go to the bathroom?” “Do you get up at night to urinate?” “Do you have a strong urge to urinate and have difficulty controlling it?”
Participants included in the study were classified according to the presence of UI (group with UI vs. group without UI). To classify the groups, the KHQ questions about “losing urine when you have a powerful desire to urinate” and “if you lose urine with physical activity, coughing or sneezing,” were used. The UI group comprised participants who reported urine loss according to the KHQ, and the group without UI was composed of participants who did not report urine loss, as shown in figure 1. This study was approved by the Ethics and Research Committee [OMITTED FOR BLINDED PURPOSES]. All participants signed an informed consent form, and the studies were conducted following the Declaration of Helsinki.
Instruments and Data Collection
Data were collected through semi-structured interviews containing sociodemographic and anthropometric data such as years of education, marital status, and age, and providing answers to the KHQ [30], KHQ-5D [10], and SF-6Dv1 [16].
King’s Health Questionnaire
The KHQ consists of 21 questions divided into eight domains (general health perception, incontinence impact, role limitations, physical limitations, social limitations, personal relationships, emotions, and sleep and energy disturbances associated with UI) and two independent Likert-type scales of urinary symptoms. The score ranges from 0 (best QoL) to 100 (worst QoL) and is measured by each domain. In this study, only the Symptom Severity Scale, which assesses the presence and severity of urinary symptoms, was used to verify the eligibility to participate in the study and questions about UI to form each group [31]. The KHQ was translated and validated in Brazil by Fonseca et al. [30].
Short Form Six Dimensions version 1
The MAUI SF-6Dv1, developed by Brazier et al. [16], describes health states on six dimensions using four to six severity levels: physical functioning (six levels), role limitations (four levels), social functioning (five levels), pain (six levels), mental health (five levels), and vitality (five levels); therefore, the SF-6Dv1 can describe 18,000 health states. The SF-6Dv1 has been translated and validated in Brazil by Cruz et al. [27].
King’s Health Questionnaire Five Dimensions
The MAUI KHQ-5D, developed by Brazier et al. [10], consists of five questions about urinary problems that are assessed in five dimensions: functional limitation, physical limitation, social limitation, emotion, and sleep. Each dimension has four levels of responses (does not affect, affects slightly, affects moderately, and affects a lot), and therefore can assess 1024 health states.
Protocol translation and cross-cultural adaptation
The translation protocol was performed after authorization was obtained through electronic contact with the authors of the KHQ-5D [10]: John E. Brazier and Con Kelleher.
As illustrated in figure 2, the translation and cross-cultural adaptation protocol of the items, instruction, and response options were carried out in five steps: i) Translation: two independent translators fluent in English but residing in Brazil, were responsible for translating the KHQ-5D from English to Brazilian Portuguese; ii) Synthesis of translations: two reviewers held a meeting to synthesize the translations into a single document; iii) Translation-back: a new translation of the new document from Brazilian Portuguese to English was performed; iv) Review Committee: a committee of six judges and two reviewers evaluated the new version translated into English and considered the grammatical and conceptual semantics; v) Pre-test: 10 women, without mental restrictions that could impair the understanding of the instrument and with symptoms of OAB (evaluated by the KHQ), participated in the pre-test. Pretest participants were asked about the layout of the form, whether they had other comments about the questionnaire, whether they considered the questions confusing, and whether the answer options were inadequate.
Acceptability was considered low when an item was judged and > 10% of the participants responded positively to these questions [22]. Understandability was considered insufficient when at least 20% of the participants found some questions difficult to answer.
Data Processing
To contemplate the objectives of this study, the utility value of the SF-6Dv1 was generated with a custom-made routine developed in R by a member of the research team, and the KHQ-5D was calculated using the KHQ package [32]. The utility values of the SF-6Dv1 and KHQ-5D were calculated according to the weights obtained in 11 countries [11,16,22–25,28,33]. Several evaluation methods have been used to elicit these weights, including the VAS, SG, ordinal preference, probability lottery equivalent, full profile, and discrete choice experiment. The most common evaluation method was the SG, as shown in table 1, which describes the validation process in several countries.
Statistical analysis
Descriptive statistics were performed to express the characteristics of the sample through means, standard deviations, frequencies, and percentages, according to the presence of UI. The Kolmogorov-Smirnov test was used to verify the normality of the data. Although the data did not meet the normality assumption, a two-way mixed-design analysis of variance (ANOVA) was used, considering that it is a sufficiently robust test to support non-parametric data [34]. A two-way mixed ANOVA was applied to verify the interaction between the presence of UI and preference indices obtained from different countries. If Mauchly's test of sphericity was statistically significant (p<0.05), the epsilon correction (Huynh-Feldt) was used to adjust the degrees of freedom. Thus, if an interaction between groups vs. the utility index of different countries, differences between groups, and differences between the utility indices of different countries were found in the main analysis, two different post hoc comparisons would be applied. The first post hoc test measured the difference in each country's utility index between groups using an independent Student’s t-test. The second post hoc (multiple comparisons) measured the difference between the utility indices of different countries within each group using a one-way ANOVA, and to counteract the problem resulting from multiple comparisons, a Bonferroni correction was applied. Spearman's correlation was used to verify the correlation between utility indices obtained through the SF-6Dv1 and KHQ-5D. A significance level of 5% was considered in the analyses, and all analyses were performed using the SPSS software (IBM SPSS Statistics, v. 22).
Table 1: Description of validation in several countries.
|
Author
|
Country
|
Year
|
Valuation methods
|
MAUI
|
Original questionnaire
|
Sample
|
Population
|
Brazier et al. [16]
|
UK
|
1998
|
VAS
|
SF-6Dv1
|
SF-36v1
|
|
General Public
|
Brazier et al.[16]
|
UK
|
1998
|
SG
|
SF-6Dv1
|
SF-36v1
|
|
General Public
|
Brazier et al.[11]
|
UK
|
2002
|
SG
|
SF-6Dv1
|
SF-36v1
|
611
|
General Public
|
Brazier et al.[22]
|
UK
|
2004
|
SG
|
SF-6Dv1
|
SF-36v1
|
611
|
General Public
|
Brazier et al.[22]
|
UK
|
2004
|
SG
|
SF-6Dv1
|
SF-12
|
611
|
General Public
|
McCabe et al.[23]
|
UK
|
2007
|
SG
|
SF-6Dv1
|
SF-36v1
|
|
|
Atroshi et al.[24]
|
UK
|
2007
|
OV
|
SF-6Dv1
|
SF-36v1
|
|
|
Lam et al.[25]
|
China
|
2008
|
SG
|
SF-6Dv1
|
SF-36v1
|
126
|
General Public
|
Ferreira et al.[26]
|
Portugal
|
2010
|
SG
|
SF-6Dv1
|
SF-36v1
|
140
|
General Public
|
Cruz et al.[27]
|
Brazil
|
2011
|
SG
|
SF-6Dv1
|
SF-36v1
|
469
|
General Public
|
Ferreira et al.[28]
|
Portugal
|
2011
|
SG
|
SF-6Dv1
|
SF-36v1
|
140
|
General Public
|
McGhee et al.[29]
|
Hong Kong
|
2011
|
SG
|
SF-6Dv1
|
SF-36v1
|
582
|
General Public
|
Méndez et al. [17]
|
Spain
|
2011
|
PLE
|
SF-6Dv1
|
SF-36v1
|
4980
|
General Public
|
Abellan Perpinan et al.[19]
|
Spain
|
2012
|
PLE
|
SF-6Dv1
|
SF-36v1
|
|
|
Craig et al.[20]
|
USA
|
2013
|
PF
|
SF-6Dv1
|
SF-36v1
|
666
|
General Public
|
Norman et al.[33]
|
Australia
|
2014
|
DCE
|
SF-6Dv1
|
SF-36v1
|
|
|
Craig et al.[20]
|
United Kingdom
|
2016
|
SG
|
SF-6Dv1
|
SF-36v1
|
|
|
Kharroubi et al.[39]
|
Lebanon
|
2020
|
SG
|
SF-6Dv1
|
SF-36v1
|
126
|
General Public
|
Kharroubi et al. [39]
|
Lebanon
|
2020
|
SG
|
SF-6Dv1
|
SF-36v1
|
126
|
General Public
|
Brazier J et al.[10]
|
United Kingdom
|
2008
|
SG
|
KHQ-5D
|
KHQ
|
110
|
Women and men with UI
|
Abbreviations: VAS, Visual Analogic Scale; SG, Standard gamble; OV, Ordinal Valuation; PLE, Probability Lottery Equivalent utilities; PD, Pivoted design; DCE, Discrete-Choice experiments; MAUI, Multi-attribute utility instrument; SF-6Dv1, Short-Form Six Dimensions version 1; KHQ-5D, King’s Health Questionnaire Five Dimensions; SF-36, 36-item Short-Form Health Survey version 1; KHQ, King’s Health Questionnaire.
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