Journal Information
Vol. 25. Issue 6.
Pages 794-802 (01 November 2021)
Share
Share
Download PDF
More article options
Visits
3221
Vol. 25. Issue 6.
Pages 794-802 (01 November 2021)
Original Research
Full text access
Translation, cross-cultural adaptation, and measurement properties of the Brazilian-Portuguese version of the idiopathic pulmonary fibrosis-specific version of the Saint George's Respiratory Questionnaire (SGRQ-I) for patients with interstitial lung disease
Visits
3221
Wagner Florentin Aguiara, Leandro Cruz Mantoania, Humberto Silvaa, Camile Ludovico Zambotia, Thatielle Garciaa, Vinicius Cavalherib,c, Marcos Ribeirod, Janelle Yorkee, Fabio Pittaa, Carlos Augusto Camilloa,f,*
a Laboratory of Research in Respiratory Physiotherapy, Department of Physiotherapy, State University Londrina, PR, Brazil
b School of Physical Therapy and Exercise Science, Faculty of Health Sciences, Curtin University, Perth, Australia
c Allied Health, South Metropolitan Health Service, Perth, Australia
d Section of Pulmonology, Department of Medicine, State University Londrina, PR, Brazil
e Division of Nursing, Midwifery and Social Work, University of Manchester, Manchester, UK
f Department of Rehabilitation Sciences, University Pitágoras UNOPAR, Londrina, PR, Brazil
This item has received
Article information
Abstract
Full Text
Bibliography
Download PDF
Statistics
Tables (12)
Table 1. Characteristics of participants.
Table 2. Reliability analysis of SGRQ-I.
Table 3. Correlations between the SGRQ-I and SF-36 questionnaire (anchor-based method).
Table 4. Discriminative validity of SGRQ-I for age, sex, educational level, cognitive status, and disease severity.
Show moreShow less
Additional material (3)
Abstract
Background

The idiopathic pulmonary fibrosis-specific version of the St George's Respiratory Questionnaire (SGRQ-I) is a valid tool to assess health-related quality of life in patients with interstitial lung diseases (ILDs).

Objective

To translate and cross-culturally adapt the SGRQ-I to Brazilian-Portuguese, and to assess its measurement properties.

Methods

Phase one consisted of the translation and cross-cultural adaptation of the questionnaire. In phase two, intra- and inter-assessor reliability (intraclass correlation coefficient [ICC]), internal consistency (Cronbach's α), minimal detectable change (MDC), ceiling/floor effects, convergent validity (correlation with SF-36 questionnaire), and discriminative validity (according to clinical characteristics) were investigated.

Results

No significant adaptations were needed during the translation process of the SGRQ-I. In phase two, 30 patients with ILD were included (15 men; age 59 ± 10 years; Forced Vital Capacity 73 [61–80]%predicted). The total score on the SGRQ-I presented excellent intra-assessor (ICC: 0.93; 95%CI: 0.85, 0.97]) and inter-assessor (ICC: 0.88; 95%CI: 0.77, 0.94) agreement. Internal consistency was considered adequate for the domains impact, activity, and total score (0.79<α<0.88) but not for symptoms (α=0.43). MDC was 12.8 points and ceiling/floor effects were found in only 3% of patients. No discriminative validity was observed, but there was adequate convergent validity.

Conclusion

The results provide preliminary evidence of adequate measurement properties and validity of the Brazilian-Portuguese version of the SGRQ-I for patients with ILDs.

Keywords:
Health-related quality of life
Interstitial lung disease
Questionnaire
Full Text
Introduction

Interstitial lung diseases (ILDs) are a heterogeneous group of pathologies with similar clinical, radiological, and functional characteristics. The occurrence of ILD varies with prevalence rates ranging from 17/105 to 80/105 and annual incidence rates ranging from 4.1/105 to 30/105.1–3 In Brazil, the incidence of interstitial pulmonary fibrosis is 0.4/10 per year, while the prevalence is 14/10.4 In addition to respiratory problems, patients with ILD show systemic manifestations that directly impact their quality of life.5

Although there is a vast number of generic instruments to assess health-related quality of life, better results are obtained when valid and specific instruments are used for targeted populations.6,7 The St George's Respiratory Questionnaire (SGRQ) was initially developed and validated to assess health-related quality of life in patients with chronic obstructive pulmonary disease (COPD).8,9 The SGRQ has acceptable validity and reliability to use in individuals with idiopathic pulmonary fibrosis.7 However, due to large clinical differences between patients with COPD and those with idiopathic pulmonary fibrosis, a specific English version of this questionnaire for this population, named the SGRQ-I, was developed.6 Although the SGRQ-I was specifically developed for patients with idiopathic pulmonary fibrosis, the clinical and functional similarities among the various subtypes of ILDs allows the use of the SGRQ-I for the broad group of ILDs. In fact, the SGRQ-I has recently been used as a clinical outcome in a randomized controlled trial investigating the effect of exercise training for patients with different ILDs.10

The SGRQ-I has been cross-culturally adapted into Spanish with adequate internal consistency, reliability, and validity.11 Likewise, the SGRQ-I may be valid for Brazilian patients with ILD; however, this has not been investigated. The aim of the present study was to translate and cross-culturally adapt the SGRQ-I to Brazilian-Portuguese and to test its measurement properties (i.e. reliability, validity, minimal detectable change (MDC), and ceiling/floor effects) in patients with ILDs.

MethodsStudy design

This methodological study was divided into two phases. In the first phase, we translated and cross-culturally adapted the SGRQ-I questionnaire to Brazilian-Portuguese. In the second phase, we investigated its measurement properties in patients with ILDs. The study was approved by the ethics committee of the Universidade Estadual de Londrina (Londrina, Paraná, Brazil) under the registry number #2.484.871. All patients provided written consent prior to participating in the study.

Participants

Patients diagnosed with ILD,12,13 age between 40 and 75 years, were recruited from the outpatient clinic of the University Hospital of the State University of Londrina (Londrina, Brazil). All patients had to present clinical stability for at least four weeks before the initial assessment and during the study. Participants' medical treatment and medication were monitored over the study period to identify potential changes in health status (e.g. exacerbations). Patients were excluded if they presented with cognitive deficits as identified with the Mini-Mental State Examination14 or if they presented any change in health status that could interfere with the assessments.

SGRQ-I

The original version of the SGRQ-I questionnaire has 34 items, divided into three domains: symptoms (6 items), activity (10 items), and impact (18 items). Scores can be calculated for the total questionnaire and separately for each domain. Each item has a specific weight. Total and domain scores range from 0 to 100, with higher scores indicating a more impaired health-related quality of life.6

Translation and cross-cultural adaptation

The translation of the English version of the SGRQ-I (EV1) to Brazilian-Portuguese followed the recommendations of the ISPOR Task Force for Translation and Cultural Adaptation of Patient-Reported Outcome Measures.15 The translation was done independently by two native Brazilian-Portuguese authors, both fluent in the English language. Both versions were then compared to each other, and the first Brazilian-Portuguese version (PV1) was created and tested in five patients with ILD. This procedure allowed the committee of experts, consisting of authors of the study (CAC and FP), and the researcher who developed the questionnaire (JY), to discuss and address any doubts or difficulties reported by the patients. The committee's role was to audit trail every step in the process of translation and cross-cultural adaptation as well as to provide solutions for problems occurring at this stage. After the analysis of PV1 by the committee of experts, the second Brazilian-Portuguese version of the questionnaire (PV2) was created. Then, PV2 was translated back into English (EV2) by a native Brazilian-Portuguese physical therapist who was fluent in English and had no prior contact with the original questionnaire. Subsequently, the original English version (EV1) and the back-translated version (EV2) were compared. Finally, small inconsistencies raised by the developer of the questionnaire were addressed in the final Brazilian-Portuguese version (PV3).

Assessment procedure

In the initial visit, all participants underwent a comprehensive clinical assessment. Lung function (whole-body plethysmography and diffusion capacity for carbon monoxide (DLCO), Vmax, CareFusion©) was evaluated following internationally accepted guidelines, and values were compared to normative data.16–20 Exercise capacity was assessed with the 6-minute walk test (6MWT).21,22 The 6MWT test was performed twice, and the highest achieved walking distance was recorded. Quadriceps strength was assessed by maximal voluntary isometric contraction (MVIC) of the dominant limb using a strain gauge (EMG System®, Brazil) attached to a stationary multigym device. Participants were instructed to perform the MVIC for six seconds, with 90° of hip and knee flexion.23 Symptoms of dyspnea were assessed using the Medical Research Council (MRC) scale (1–5 points),24 and health-related quality of life was assessed using the 36-item Short-Form Health Survey (SF-36).25 Physical activity in daily life was assessed using an activity monitor (Actigraph®, wGT3x-BT). Patients were instructed to use the activity monitor on their waist for six consecutive days, for 24 h, including sleeping time.26 Acceleration data were sampled at 30 Hz and analysed in 1-minute epochs. A complete data set was considered valid if the patient wore the activity monitor for at least 8 h/day for at least four weekdays.27 The intensities of activities were stratified according to metabolic equivalent of tasks (METs). Light-intensity activities were those demanding ≤1.5 METs while moderate-intensity activities were those demanding 3–6 METs.27 Outcomes related to physical activity in daily life included in the analysis were: daily steps and activities of light and moderate intensity.

For the reliability analysis, the SGRQ-I (which was researcher-administered) was applied at three time-points: initial visit and two additional visits. Each time-point took place with an interval of 5–7 days. This timeframe is considered adequate for not allowing participants to remember their answers and minimizing changes in participants' health status.28–30 The questionnaire was administered by two trained assessors, both physical therapists with at least four years of clinical experience. The use of two assessors allowed us to determine the intra- and inter-assessor reliability. The assessors were trained on how to perform interviews using verbal and non-verbal communication techniques to establish good rapport with patient. The questionnaire was always administered at the same place (a quiet and climate-controlled room) and at the same time of day to enhance standardisation of the procedure. Illiteracy is not uncommon among Brazilian patients with chronic respiratory diseases.31 So, given that scores may vary depending on how the questionnaire is administered (ie, self- versus researcher-administered), participants in this study were interviewed by two different assessors.30 Assessor 1 (WFA) applied the questionnaire in the first and third visits, while assessor 2 (HS) applied the questionnaire during the second visit. Misunderstandings and queries related to the questions were clarified according to the SGRQ-I application manual.6 The scores of the SGRQ-I obtained at each visit and the time required to complete the questionnaire at each visit were compared.

Finally, the SF-36 applied during the initial visit was used in the validation of the SGRQ-I (anchor-based method). It is a generic assessment tool to assess the quality of life that is easy to understand and apply. It is a multidimensional questionnaire that comprises 36 items, divided into eight domains: physical functioning, physical role, pain index, general health perceptions, vitality, social functioning, emotional role, and mental health index. Total score ranges from 0 to 100, where zero corresponds to the worst and 100 the best overall quality of life.25 The eight domains of the SF-36 are grouped into two major components: physical and mental. These scores vary from 0 to 50, in which the lower the score, the higher the physical and mental impairment. The SF-36 was chosen for the validation of SGRQ-I because it has been used in patients with ILD, and present acceptable construct and criterion validity to investigate the quality of life in this population.7,32,33

Statistical analysis

Descriptive statistics were used to characterize the sample. Continuous variables were described as mean ± standard deviation, or median [interquartile range], depending on data distribution. The Statistical Analysis System (SAS) University Edition® was the software of choice to perform the statistical analysis.

Reliability analysis

Intraclass correlation coefficient (ICC) and 95% confidence interval (CI) were used to determine the reliability of the questionnaire. The ICC selection followed the McGraw and Wong convention34 and the "two-way mixed effects, single measurement, absolute agreement" was used to investigate intra- and inter-assessor reliability. The reliability was classified as poor (ICC<0.5), moderate (0.5≤ICC<0.75), good (0.75≤ICC<0.9), or excellent (ICC≥0.9).35 Absolute reliability of the data was determined using the standard error of measurement (SEM). The SEM was calculated based on the intra-assessor reliability. The lower the SEM value, the more reliable the measurement.36 Cronbach's α coefficient was used to verify the internal consistency of the SGRQ-I. Values >0.7 were deemed acceptable.37 The MDC was calculated using the equation MDC=z−score×SD×√2(1−r) where the z-score represents the CI from a normal distribution (i.e. 1.96), SD is the standard deviation of the scores and r is the coefficient of the intra-assessor test-retest reliability (i.e. ICC).38 Ceiling and floor effects were calculated by estimating the percentage of patients whose scores lied within the 10% best (ceiling effect) or the 10% worst scores (floor effect) of the SGRQ-I.39

Validity analysis

Spearman's correlation coefficient was used to verify construct validity (i.e. convergent validity). For the validity analysis, we correlated the total SGRQ-I score obtained in the initial visit with the score of the Physical Health component of the SF-36. We hypothesized that the SGRQ-I would show at least moderate correlation with the Physical Health component of the SF-36. The magnitude of this correlation is expected to be at least moderate (r > 0.39).40,41 We also conducted an exploratory analysis to investigate whether SGRQ-I score correlated with other measures, such as the Medical Research Council (MRC) scale, pulmonary function, and exercise capacity. Discriminative validity was done using a one-way ANOVA comparing groups of patients according to disease severity (i.e. i-Forced Vital Capacity, FVC<55%predicted; ii-55%42 Additionally, patients were stratified according to age, sex, educational level, and cognitive status (Mini-mental State Examination) and the SGRQ-I scores for each category were compared using student's t-test or Mann-Whitney test depending on data distribution. For the discriminative validity analysis, we hypothesized that the questionnaire would be able to detect differences according to disease severity but would not detect difference across the groups defined by age, sex, educational level, and cognitive status. A posteriori analysis was performed to assess the statistical power of the SGRQ-I validation with the score of the SF-36 physical domain. Power analysis was done using specific software (G*Power 3.1, University of Dusseldorf). Statistical significance was set at p < 0.05.

Results

Participants' characteristics are described in Table 1. Thirty patients diagnosed with ILD were initially assessed and considered eligible for inclusion in the study (15 men; mean age of 59 ± 10 years; median FVC = 73% [61–80] of the predicted value). The most prevalent diagnosis was idiopathic pulmonary fibrosis (n = 18), followed by pulmonary fibrosis related to diseases of the connective tissue (n = 5), diseases related to inhalation of particles (n = 4), and non-specific interstitial pneumonia (n = 3). Most of the participants were literate (93%) but had a low education level (i.e. 50% of them had only elementary education completed). The cross-cultural adaptation and translation of the questionnaire did not undergo significant changes except for item 4 of Section 5. The original question asks, "My breathing makes it difficult to do things such… play bowls or play golf". These two activities (bowls and golf) were excluded from the item as they were not applicable to Brazilian patients (Supplemental online material).

Table 1.

Characteristics of participants.

Variable  Participants (n = 30) 
Sex, M (%)  15 (50%) 
Age, years  59 ± 10 
Body composition   
BMI, kg/m2  27.4 ± 5.3 
Literacy, yes (%)  28 (93%) 
Education: Elementary/Middle-High/College, n(%)  15 (50%)/13 (43%)/2 (7%) 
Pulmonary Function   
FVC,% predicted  73 [61–80] 
FEV1,% predicted  73 [62–84] 
FEV1/FVC  83 [78–87] 
TLC,% predicted  72 [65–89] 
DLCO,% predicted  49 [35–67] 
Exercise Capacity   
6MWT, m  469 ± 100 
6MWT,% predicted  86 ± 17 
Peripheral Muscle Strength   
Quadriceps force, N  395 ± 174 
Physical Activity in Daily Life   
Steps, n/day  5190 [3863–6916] 
Light-intensity activity (≤1.5METs), min/day  308 ± 90 
Moderate-intensity activity (3–6METs), min/day  12 ± 9 
Health-related quality of life (SF-36)   
Physical functioning,% of impact  41 ± 24 
Physical role,% of impact  41 ± 41 
Pain index,% of impact  53 ± 28 
General health perceptions,% of impact  44 ± 18 
Vitality,% of impact  59 ± 16 
Emotional role,% of impact  70 ± 26 
Social functioning,% of impact  53 ± 41 
Mental health index,% of impact  68 ± 18 
Health-related quality of life (SGRQ-I)   
SGRQ-I Symptoms, score  50 [26–69] 
SGRQ-I Activities, score  74 [50–89] 
SGRQ-I Impact, score  44 [35–54] 
SGRQ-I Total, score  50 [36–63] 
Symptoms   
MRC, score  3 [2–4] 

Data are presented as mean ± SD or median [interquartile range] or frequency (percentage) unless otherwise stated.

Abbreviations: 6MWT, six-minute walk test; BMI, body mass index; DLCO, carbon monoxide diffusion capacity; FEV1, forced expired volume in the first second; FVC, forced vital capacity; METs, Metabolic equivalent of task; MRC, Medical Research Council Dyspnoea scale; SF-36, Medical Outcomes Short-Form Health Survey quality of life questionnaire; SGRQ-I, Saint George Respiratory Questionnaire for patients with Interstitial Pulmonary Fibrosis; TLC, Total lung capacity.

The median length of time for completing the SGRQ-I during the initial, second, and third visits was 461 s [413–536], 476 s [430–552], and 422 s [368–470], respectively (p = 0.052). The median SGRQ-I total score for the 3 visits was 50 [36–63] points, 48 [38 −70] points, and 56 [40–68] points, respectively (p = 0.94). SGRQ-I domains and total scores for the initial visit are reported in Table 1. The total score of SGRQ-I had excellent intra-assessor (ICC= 0.93; 95%CI: 0.85, 0.97]) and inter-assessor (ICC = 0.88; 95%CI: 0.77, 0.94) reliability. Internal consistency analyses were deemed adequate for total score (Cronbach's α = 0.88), activity (Cronbach's α = 0.83), and impact (Cronbach's α = 0.79) domains but inadequate for symptoms domain (Cronbach's α = 0.48). The SEM for the total score was 6.5 points (or 13%) and the MDC was 12.8 points. The percentage of patients with maximum and minimum score were respectively 3% and 0%, indicating no ceiling and floor effects. Reliability date are provided in Table 2.

Table 2.

Reliability analysis of SGRQ-I.

Assessment  ICC (95% CI) 
Symptoms   
Intra-assessor  0.90 (0.78, 0.95)* 
Inter-assessor  0.76 (0.56, 0.88)* 
Activities   
Intra-assessor  0.85 (0.70, 0.93)* 
Inter-assessor  0.84 (0.70, 0.92)* 
Impact   
Intra-assessor  0.91 (0.80, 0.96)* 
Inter-assessor  0.80 (0.63, 0.90)* 
Total   
Intra-assessor  0.93 (0.85, 0.97)* 
Inter-assessor  0.88 (0.77, 0.94)* 

Abbreviations: 95% CI, 95% Confidence Interval; ICC, Intraclass Correlation Coefficient; SGRQ-I, Saint George Respiratory Questionnaire for patients with Interstitial Pulmonary Fibrosis; r, Spearman's correlation coefficient. *p<0.05.

For the validity analysis, the total SGRQ-I score showed negative moderate correlation with the physical health component of the SF-36 (r = −0.53; p < 0.05). The full set of correlations between SGRQ-I and the domains of the SF-36 is provided in Table 3. There was no significant correlation between any domain of the SF-36 and SGRQ-I symptoms domains (−0.35≤r ≤ 0.20; p > 0.05 for all). The impact domain of the SGRQ-I correlated with the functional capacity, general health status, and vitality domains of the SF-36 (−0.71 ≤ r ≤ −0.39; p < 0.05 for all).

Table 3.

Correlations between the SGRQ-I and SF-36 questionnaire (anchor-based method).

  Domains
Variable  Symptoms  Activities  Impact  Total Score 
SF-36 (Physical functioning)  −0.29  −0.71*  −0.71*  −0.66* 
SF-36 (Physical role)  −0.05  −0.24  −0.28  −0.24 
SF-36 (Pain index)  −0.32  −0.45*  −0.36  −0.40* 
SF-36 (General health perceptions)  −0.27  −0.49*  −0.45*  −0.44* 
SF-36 (vitality)  −0.35  −0.43*  −0.39*  −0.40* 
SF-36 (Emotional role)  0.06  −0.25  −0.14  −0.16 
SF-36 (Social functioning)  0.10  −0.03  −0.18  −0.08 
SF-36 (Mental health index)  0.20  −0.07  0.09  0.08 
Physical health  −0.52*  −0.32  −0.59*  −0.53* 
Mental health  0.05  0.10  0.03  0.01 

SF-36: Medical Outcomes Short-Form Health Survey quality of life questionnaire; *p < 0.05.

The SGRQ-I was not able to discriminate health-related quality of life according to the disease severity, age, sex, educational level, and cognitive status (discriminative validity) (Table 4). Finally, the power analysis of the correlation between SGRQ-I total score and physical health component of the SF-36 was 0.83.

Table 4.

Discriminative validity of SGRQ-I for age, sex, educational level, cognitive status, and disease severity.

  Symptoms  Activities  Impact  Total Score 
Age         
≥ 60 years old  51 [28–66]  67 [58–79]  46 [36–54]  49 [36–62] 
< 60 years old  45 [31–71]  78 [43–89]  42 [33–54]  49 [31–65] 
Sex         
Man  50 [35–66]  68 [47–79]  40 [28–50]  48 [34–62] 
Woman  46 [27–84]  78 [58–89]  46 [34–57]  54 [40–67] 
Educational level         
Elementary  50 [27–60]  58 [47–78]  38 [27–50]  49 [34–60] 
Middle-High  51 [43–84]  78 [69–89]  44 [36–54]  54 [47–67] 
College  22 [17–29]  59 [30–89]  37 [14–60]  41 [19–62] 
Cognitive status         
≤ 24 points, Mini-mental  60 [27–84]  70 [39–100]  54 [15–88]  59 [23–90] 
> 24 points, Mini-mental  49 [29–67]  73 [50–89]  42 [35–54]  49 [36–62] 
Disease severity         
FVC<55%predicted  68 [42–68]  68 [58–89]  40 [38–45]  49 [40–50] 
55%  50 [46–66]  78 [48–89]  43 [36–54]  61 [55–65] 
FVC ≥70% predicted  44 [27–60]  70 [50–79]  48 [32–55]  49 [36–63] 

Data are presented as median [interquartile range]. Abbreviations: FVC, forced vital capacity. No significant differences were found across all categories (p > 0.05 for all).

SGRQ-I scores significantly correlated with the MRC (symptoms r = 0.42, p = 0.02; activity r = 0.71, p < 0.0001; impact r = 0.62, p = 0.0004; total score r = 0.66, p = 0.0001). There was no significant correlation between SGRQ-I scores and exercise capacity [−0.36 ≤ r ≤ −0.25; p > 0.05 for all], pulmonary function outcomes [−0.03 ≤r ≤ 0.20; p > 0.05 for all], and daily activities of light or moderate intensities (0.16 ≤r ≤ 0.30; p > 0.05 for all). Daily steps correlated significantly with symptoms of the SGRQ-I (r = 0.37, p = 0.04).

Discussion

In the present study, the translated version of the SGRQ-I demonstrated good to excellent intra- and inter-rater reliability and good to excellent internal consistency. Further, the Brazilian-Portuguese version of the SGRQ-I is valid to be used in patients with ILDs. Consistent with previous work, the reliability analysis in this study demonstrated excellent values of ICC in most domains and total score.6,43 Yet, scores were somewhat higher in the intra-assessor analysis. The difference in total scores between assessors, however, was negligible with a clear overlap of the CIs. Also, in the intra-assessor analysis the scores of the second application were slightly higher, which suggests a learning effect. This, however, is not supported by the statistical analysis which showed adequate ICC values and no statistical difference between the assessments. The values of Cronbach's α confirmed the adequate internal consistency of the SGRQ-I except for symptoms (i.e. α < 0.7). In a systematic review of the psychometric properties of the SGRQ in patients with idiopathic pulmonary fibrosis, Swigris et al.33 also reported low values of internal consistency in the symptoms domain. A possible explanation for this is that questions related to symptom assess respiratory complaints that are not common in ILDs. For instance, items 4 and 5 of the first part of the questionnaire refers to "wheezing" and "respiratory crisis," symptoms more commonly reported by patients with obstructive lung diseases.

To the best of the authors' knowledge, this is the first study investigating the MDC of the SGRQ-I. This statistical approach helps clinicians to identify changes that are not merely a normal variation of the tool but instead changes in the clinical condition of the patient.44 It, however, does not mean that changes on MDC superior to 12.8 points are considered clinically relevant for patients. Future studies are needed to determine whether this cut-off resembles clinically relevant changes in patient's quality of life.

Recently, Prior and colleagues45 demonstrated that less than 15% of patients with ILDs reached highest (celling effect) or lowest (floor effect) deciles of possible scores on the SGRQ-I. Consistent with these results, our findings also did not identify a significant proportion of patients with maximal/minimum scores in the questionnaire (i.e. less than 5% of patients). Albeit these results should be confirmed in larger sample size, this is a good indication that the tool is not limited by construct constraints.

The analysis of the construct validity of the SGRQ-I or Brazilian-Portuguese language presented similar values to those observed in the validation of the English version.6 These results confirm that the translation and the cross-cultural adaptation in the present study did not impact on the essence of the questionnaire. Indeed, there was no need to adapt the text during the translation process significantly. Only item 4 of the fifth section was changed due to environmental and cultural differences, as reported in the results section. Importantly, the questionnaire was designed to be applied in idiopathic pulmonary fibrosis. The present study expands the results of the reliability and validity of the SGRQ-I questionnaire for utilisation in patients with ILD.

The analysis of discriminative validity showed that it was not possible to anticipate a better or worse quality of life based on age, sex, educational level, cognitive status, and the severity of the disease. This finding, however, needs to be interpreted with caution. The sample size of the present investigation was not powered for this analysis, and these results likely change if using a larger sample size. Additional validation analyses were recently published using the English version of the SGRQ-I and confirmed that it was good at discriminating patients with different stages of the disease.45

Similar to Capparelli et al.,11 we also found a significant correlation between SGRQ-I and MRC scores. Conversely, none of the other investigated outcomes presented significant correlations. This is not particularly surprising as the SGRQ-I also failed to show strong correlations of the same outcomes in the validation study for the English language.6 Lubin et al.46 demonstrated that dyspnea was one of the strongest determinants of health-related quality of life in patients with idiopathic pulmonary fibrosis, being superior to disease severity. In other respiratory diseases, a reduced exercise capacity present meaningful relationship with health-related quality of life, especially in more severely affected patients.47 The sample in the present study did not include many patients with marked reduction of exercise capacity or muscle strength. It is possible to hypothesise that the lack of correlation between SGRQ-I and 6MWT is a consequence of the preserved muscle function in the assessed patients.

The results of the present study need to be interpreted in light of some potential limitations. First, the sample size is somewhat small. The low prevalence of patients with ILD and the monocentric design of the present study have limited participant recruitment. However, other authors found acceptable results with a similar sample size.11 But, the post-hoc power analysis of the SGRQ-I validation (power=0.83) confirmed the sample size of the present study did not hamper the interpretation of our results. Second, the questionnaire was applied in patients with different types of ILD, despite the original version being specifically developed for patients with idiopathic pulmonary fibrosis. Although 60% of the study sample was comprised of people with idiopathic pulmonary fibrosis, our results were similar to the previous study on the validity of SGRQ-I.6 Also, investigating the validity of SGRQ-I in specific diseases was beyond the scope of the present study. Third, in the process of translation and cross-cultural adaptation of questionnaires, the backward translation should ideally be performed by two independent researchers. Finally, the SGRQ-I was initially developed to be self-administered. In the current study, questionnaires were researcher-administered. This was done as we anticipated patients with low literacy levels to be included in the present study. Given there is considerable variation of scores when questionnaires are self- versus researcher-administered, we attempted to reduce bias by standardising the application method.31

Conclusion

The Brazilian-Portuguese version of SGRQ-I, albeit conducted in a relatively small sample, seems to have adequate measurement properties justifying its use in the Brazilian population.

Conflicts of interest

None of the authors have conflicts of interest to declare.

Acknowledgments

WFA was receipient of Fundação Araucária/Brazil fellowship. HS, TG and LCM were reciepients of CAPES/Brazil fellowships. CAC is supported by FUNADESP, Brazil. VC is supported by Cancer Council NSW/Australia. The study was partially funded by CNPq, Brazil (426509/2018-8).

Appendix
The Brazilian-Portuguese translated version of the SGRQ-I
Questionário do Hospital Saint George na Doença Respiratória VERSÃO PARA FIBROSE PULMONAR IDIOPÁTICA - SGRQ-I

Este questionário é desenvolvido para nos ajudar a compreender até que ponto a sua condição respiratória perturba você e como isso afeta sua vida. Nós o utilizamos para descobrir quais os aspectos da sua doença que causam mais problema. Estamos interessados em saber o que você sente e não o que os médicos, enfermeiros e fisioterapeutas pensam que você sente.

Leia atentamente as instruções com atenção e pergunte caso não entenda algo. Não gaste muito tempo em suas respostas.

Nome: ……………………………Data: ………………

ID: ………………………

Idade: …………………Sexo: () Masculino () Feminino

Marque uma das opções que mostra como você considera seu estado de saúde atual.

Muito boa□  Boa□  Regular□  Ruim□  Muito ruim□ 

Copyright reserved

P.W. Jones, PhD FRCP

Professor of Respiratory Medicine,

St. George's University of London,

Jenner Wing,

Cranmer Terrace, Tel. +44 (0) 20 8725 5371

London SW17 ORE, UK. Fax +44 (0) 20 8725 5955

Parte 1

Nas questões abaixo, assinale aquela que melhor identifica seus problemas respiratórios atualmente. Por favor, assinale com um “X” em um dos quadrados de cada questão abaixo.

  A maioria dos dias da semana  Só com infecções respiratórias  Nunca 
1. Eu tusso  □  □  □ 
2. Eu tenho catarro (escarro)  □  □  □ 
3. Eu tenho falta de ar  □  □  □ 
4. Eu tenho chiado no peito  □  □  □ 

5. Durante uma semana típica, quantas vezes você tem crises respiratórias: Por favor assinale uma resposta:

□ Mais de uma crise  □ Nenhuma crise

6. Durante uma semana típica, quantos dias bons você tem? (ex: sem problemas respiratórios): Por favor assinale uma resposta:

□ Nenhum dia  □ Alguns dias □ Todos os dias são bons dias

Parte 2

Seção 1: Se você já teve um trabalho remunerado, assinale um dos quadrados:

Minha condição respiratória interfere ou me fez parar de trabalhar □

Meu problema respiratório não afeta meu trabalho □

Seção 2: As perguntas abaixo referem-se às atividades que normalmente provocam falta de ar em você.

Por favor, assinale com um “X” no quadrado de cada questão abaixo, indicando se você sentiu falta de ar em alguma dessas atividades atualmente:

  VERDADEIRO  FALSO 
1. Tomando banho ou vestindo-se  □  □ 
2. Caminhando dentro de casa  □  □ 
3. Caminhando em terreno plano  □  □ 
4. Subindo um lance de escadas  □  □ 
5. Praticando esportes ou jogos que impliquem esforço físico  □  □ 

Seção 3: Mais algumas perguntas sobre a sua tosse e a sua falta de ar.

Por favor, assinale com um “X” no quadrado de cada pergunta abaixo de acordo com o seu caso atualmente.

  VERDADEIRO  FALSO 
1. Minha tosse me causa dor  □  □ 
2. Minha tosse me deixa cansado  □  □ 
3. Tenho falta de ar quando falo  □  □ 
4. Tenho falta de ar quando me inclino (dobro meu corpo para frente)  □  □ 
5. Minha tosse ou falta de ar perturba o meu sono  □  □ 
6. Fico exausto com facilidade  □  □ 

Seção 4: Perguntas sobre outros efeitos que o seu problema respiratório possa ter causado em você.

Por favor, assinale com um “X” no quadrado de cada pergunta abaixo de acordo com o seu caso atualmente.

  VERDADEIRO  FALSO 
1. Minha tosse ou falta de ar me deixa envergonhado em publico  □  □ 
2. Meu problema respiratório é inconveniente para minha família, amigos ou vizinhos  □  □ 
3. Tenho medo ou pânico quando não consigo respirar  □  □ 
4. Sinto que não tenho controle sobre a minha doença respiratória  □  □ 
5. Fazer exercício não é seguro para mim  □  □ 
6. Tudo que eu faço parece um esforço muito grande  □  □ 

Seção 5:

As perguntas seguintes se referem às atividades que podem ser afetadas pela sua condição respiratória.

Por favor, assinale com um “X” no quadrado de cada pergunta abaixo no qual acredita se aplicar melhor a você por causa da suacondição respiratória.

  VERDADEIRO  FALSO 
1. Demoro muito tempo para realizar tarefas como trabalho de casa, ou tenho que parar para descansar  □  □ 
2. Quando subo um lance de escadas, vou muito devagar, ou tenho que parar para descansar  □  □ 
3. Se estou muito apressado ou caminho mais depressa, tenho que parar para descansar ou ir mais devagar  □  □ 
4. Minha respiração torna difícil fazer coisas como subir ladeiras, carregar objetos subindo escadas, cuidar do jardim, ou dançar.  □  □ 
5. Por causa da minha respiração tenho dificuldades para desenvolver atividades como: trabalho manual pesado, correr, nadar rápido ou praticar esportes muito cansativos  □  □ 

Seção 6: Gostaríamos de saber o quanto sua condição respiratória geralmente afeta suas atividades do dia-a-dia. Por favor, assinale com um “X” no quadrado de cada questão abaixo, indicando a que melhor se aplica a você por causa da suacondição respiratória.

  VERDADEIRO  FALSO 
1. Eu não consigo praticar esportes ou jogos que impliquem esforço físico  □  □ 
2. Eu não consigo sair de casa para fazer compras  □  □ 
3. Eu não consigo fazer trabalho de casa  □  □ 
4. Eu não consigo me mover para longe da minha cama ou da cadeira  □  □ 

Agora, por favor assinale com um “X” a resposta que melhor define a forma como você é afetado pela sua condição respiratória:

Não me impede de fazer nenhuma das coisas que gostaria de fazer  □ 
Impede-me de fazer uma ou duas coisas que eu gostaria de fazer  □ 
Impede-me de fazer a maioria das coisas que eu gostaria de fazer  □ 
Impede-me de fazer tudo que eu gostaria de fazer  □ 

References
[1]
D.B. Coultas, R.E. Zumwalt, W.C. Black, R.E. Sobonya.
The epidemiology of interstitial lung diseases.
Am J Respir Crit Care Med, 150 (1994), pp. 967-972
[2]
A. Karakatsani, D. Papakosta, A. Rapti, et al.
Epidemiology of interstitial lung diseases in Greece.
Respir Med, 103 (2009), pp. 1122-1129
[3]
B. Musellim, G. Okumus, E. Uzaslan, et al.
Epidemiology and distribution of interstitial lung diseases in Turkey.
Clin Respir J, 8 (2014), pp. 55-62
[4]
J. Baddini-Martinez, C.A. Pereira.
How many patients with idiopathic pulmonary fibrosis are there in Brazil?.
J Bras Pneumol, 41 (2015), pp. 560-561
[5]
B.G. Baldi, C.A. Pereira, A.S. Rubin, et al.
Highlights of the Brazilian Thoracic Association guidelines for interstitial lung diseases.
J Bras Pneumol, 38 (2012), pp. 282-291
[6]
J. Yorke, P.W. Jones, J.J. Swigris.
Development and validity testing of an IPF-specific version of the St George's Respiratory Questionnaire.
Thorax, 65 (2010), pp. 921-926
[7]
J.A. Chang, J.R. Curtis, D.L. Patrick, G. Raghu.
Assessment of health-related quality of life in patients with interstitial lung disease.
Chest, 116 (1999), pp. 1175-1182
[8]
P.W. Jones, F.H. Quirk, C.M. Baveystock.
The St George's Respiratory Questionnaire.
Respir Med, 85 (1991), pp. 25-31
[9]
P.W. Jones, F.H. Quirk, C.M. Baveystock, P. Littlejohns.
A self-complete measure of health status for chronic airflow limitation. The St. George's Respiratory Questionnaire.
Am Rev Respir Dis, 145 (1992), pp. 1321-1327
[10]
L.M. Dowman, C.F. McDonald, C.J. Hill, et al.
The evidence of benefits of exercise training in interstitial lung disease: a randomised controlled trial.
[11]
I. Capparelli, M. Fernandez, M. Saadia Otero, et al.
Translation to Spanish and validation of the specific Saint George's Questionnaire for idiopathic pulmonary fibrosis.
Arch Bronconeumol, 54 (2018), pp. 68-73
[12]
F. Maltais, M. Decramer, R. Casaburi, et al.
An official American Thoracic Society/European Respiratory Society statement: update on limb muscle dysfunction in chronic obstructive pulmonary disease.
Am J Respir Crit Care Med, 189 (2014), pp. e15-e62
[13]
G. Raghu, B. Rochwerg, Y. Zhang, et al.
An Official ATS/ERS/JRS/ALAT Clinical Practice Guideline: treatment of Idiopathic Pulmonary Fibrosis. An Update of the 2011 Clinical Practice Guideline.
Am J Respir Crit Care Med, 192 (2015), pp. e3-19
[14]
R.A. Lourenco, R.P. Veras.
Mini-Mental State Examination: psychometric characteristics in elderly outpatients.
Rev Saude Publica, 40 (2006), pp. 712-719
[15]
D. Wild, A. Grove, M. Martin, et al.
Principles of good practice for the translation and cultural adaptation process for patient-reported outcomes (PRO) measures: report of the ISPOR task force for translation and cultural adaptation.
Value Health, 8 (2005), pp. 94-104
[16]
N. Macintyre, R.O. Crapo, G. Viegi, et al.
Standardisation of the single-breath determination of carbon monoxide uptake in the lung.
Eur Respir J, 26 (2005), pp. 720-735
[17]
M.R. Miller, J. Hankinson, V. Brusasco, et al.
Standardisation of spirometry.
Eur Respir J, 26 (2005), pp. 319-338
[18]
J. Wanger, J.L. Clausen, A. Coates, et al.
Standardisation of the measurement of lung volumes.
Eur Respir J, 26 (2005), pp. 511-522
[19]
C.A. Pereira, T. Sato, S.C. Rodrigues.
New reference values for forced spirometry in white adults in Brazil.
J Bras Pneumol, 33 (2007), pp. 397-406
[20]
R.O. Crapo, A.H. Morris.
Standardized single breath normal values for carbon monoxide diffusing capacity.
Am Rev Respir Dis, 123 (1981), pp. 185-189
[21]
R.R. Britto, V.S. Probst, A.F. de Andrade, et al.
Reference equations for the six-minute walk distance based on a Brazilian multicenter study.
Braz J Phys Ther, 17 (2013), pp. 556-563
[22]
A.E. Holland, M.A. Spruit, T. Troosters, et al.
An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease.
Eur Respir J, 44 (2014), pp. 1428-1446
[23]
N.S. Hopkinson, R.C. Tennant, M.J. Dayer, et al.
A prospective study of decline in fat free mass and skeletal muscle strength in chronic obstructive pulmonary disease.
Respir Res, 8 (2007), pp. 25
[24]
J.C. Bestall, E.A. Paul, R. Garrod, R. Garnham, P.W. Jones, J.A. Wedzicha.
Usefulness of the Medical Research Council (MRC) dyspnoea scale as a measure of disability in patients with chronic obstructive pulmonary disease.
Thorax, 54 (1999), pp. 581-586
[25]
R.M. Ciconelli, M.B. Ferraz, W. Santos, I. Meinão, M.R. Quaresma.
Brazilian-Portuguese version of the SF-36. A reliable and valid quality of life outcome measure (Article in Portuguese).
Rev Bras Reumatol, 39 (1999), pp. 8
[26]
R.A. Rabinovich, Z. Louvaris, Y. Raste, et al.
Validity of physical activity monitors during daily life in patients with COPD.
Eur Respir J, 42 (2013), pp. 1205-1215
[27]
H. Demeyer, C. Burtin, H. Van Remoortel, et al.
Standardizing the analysis of physical activity in patients with COPD following a pulmonary rehabilitation program.
Chest, 146 (2014), pp. 318-327
[28]
J. Yorke, I. Armstrong.
The assessment of breathlessness in pulmonary arterial hypertension: reliability and validity of the Dyspnoea-12.
Eur J Cardiovasc Nurs, 13 (2014), pp. 506-514
[29]
J. Yorke, P. Corris, S. Gaine, et al.
emPHasis-10: development of a health-related quality of life measure in pulmonary hypertension.
Eur Respir J, 43 (2014), pp. 1106-1113
[30]
L.B. Mokkink, C.A. Prinsen, L.M. Bouter, H.C. Vet, C.B. Terwee.
The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) and how to select an outcome measurement instrument.
Braz J Phys Ther, 20 (2016), pp. 105-113
[31]
G.L. Moreira, F. Pitta, D. Ramos, et al.
Portuguese-language version of the Chronic Respiratory Questionnaire: a validity and reproducibility study.
J Bras Pneumol, 35 (2009), pp. 737-744
[32]
S. Witt, E. Krauss, M.A.N. Barbero, et al.
Psychometric properties and minimal important differences of SF-36 in Idiopathic Pulmonary Fibrosis.
[33]
J.J. Swigris, D. Esser, C.S. Conoscenti, K.K. Brown.
The psychometric properties of the St George's Respiratory Questionnaire (SGRQ) in patients with Idiopathic Pulmonary Fibrosis: a literature review.
Health Qual Life Outcomes, 12 (2014), pp. 124
[34]
K.O. McGraw, S.P. Wong.
Forming inferences about some intraclass correlation coefficients.
Psychol Methods, 1 (1996), pp. 17
[35]
T.K. Koo, M.Y. Li.
A guideline of selecting and reporting intraclass correlation coefficients for reliability research.
J Chiropr Med, 15 (2016), pp. 155-163
[36]
G. Atkinson, A.M. Nevill.
Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine.
Sports Med, 26 (1998), pp. 217-238
[37]
M. Tavakol, R. Dennick.
Making sense of Cronbach's alpha.
Int J Med Educ, 2 (2011), pp. 53-55
[38]
S.M. Haley, M.A. Fragala-Pinkham.
Interpreting change scores of tests and measures used in physical therapy.
Phys Ther, 86 (2006), pp. 735-743
[39]
S.J. Bennet, N.B. Oldridge, G.J. Eckert, et al.
Discriminant properties of commonly used quality of life measures in heart failure.
Qual Life Res, 11 (2002), pp. 349-359
[40]
M.R. Franco, R.Z. Pinto, K. Delbaere, et al.
Cross-cultural adaptation and measurement properties testing of the Iconographical Falls Efficacy Scale (Icon-FES).
Braz J Phys Ther, 22 (2018), pp. 291-303
[41]
L.B. Calixtre, C.L. Fonseca, B. Gruninger, D.H. Kamonseki.
Psychometric properties of the Brazilian version of the Bournemouth questionnaire for low back pain: validity and reliability.
Braz J Phys Ther, (2020),
[42]
S.D. Nathan, O.A. Shlobin, N. Weir, et al.
Long-term course and prognosis of idiopathic pulmonary fibrosis in the new millennium.
Chest, 140 (2011), pp. 221-229
[43]
J.J. Swigris, K.K. Brown, J. Behr, et al.
The SF-36 and SGRQ: validity and first look at minimum important differences in IPF.
Respir Med, 104 (2010), pp. 296-304
[44]
H.C. de Vet, C.B. Terwee, R.W. Ostelo, H. Beckerman, D.L. Knol, L.M. Bouter.
Minimal changes in health status questionnaires: distinction between minimally detectable change and minimally important change.
Health Qual Life Outcomes, 4 (2006), pp. 54
[45]
T.S. Prior, N. Hoyer, S.B. Shaker, et al.
Validation of the IPF-specific version of St. George's Respiratory Questionnaire.
Respir Res, 20 (2019), pp. 199
[46]
M. Lubin, H. Chen, B. Elicker, K.D. Jones, H.R. Collard, J.S. Lee.
A comparison of health-related quality of life in idiopathic pulmonary fibrosis and chronic hypersensitivity pneumonitis.
Chest, 145 (2014), pp. 1333-1338
[47]
Y.S. Punekar, J.H. Riley, E. Lloyd, M. Driessen, S.J. Singh.
Systematic review of the association between exercise tests and patient-reported outcomes in patients with chronic obstructive pulmonary disease.
Int J Chron Obstruct Pulmon Dis, 12 (2017), pp. 2487-2506
Copyright © 2021. Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia
Idiomas
Brazilian Journal of Physical Therapy
Article options
Tools
Supplemental materials
en pt
Cookies policy Política de cookies
To improve our services and products, we use "cookies" (own or third parties authorized) to show advertising related to client preferences through the analyses of navigation customer behavior. Continuing navigation will be considered as acceptance of this use. You can change the settings or obtain more information by clicking here. Utilizamos cookies próprios e de terceiros para melhorar nossos serviços e mostrar publicidade relacionada às suas preferências, analisando seus hábitos de navegação. Se continuar a navegar, consideramos que aceita o seu uso. Você pode alterar a configuração ou obter mais informações aqui.