We followed the good practice principles to translate and culturally adapt health outcomes instruments18 and the Cosmin taxonomy to validate the obtained Portuguese version19.
Cultural adaptation
Before initiating this study, we contacted MAPI Research Institute to obtain permission to validate a Portuguese version of this instrument. We received the information that a Portuguese non-validated version already existed, following the Food and Drug Administration (FDA) guidance on translation20, and that we should use the version located on the MAPI website.
We still felt the necessity to perform a clinical review with two rheumatologists and a cognitive debriefing with patients to content validate this Portuguese version.
Participants
To validate the SHAQ, we then invited consecutive patients from five Portuguese Hospital Centres to participate in this study between January and April 2022. Included patients fulfilled the 2013 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria for the classification of diffuse SSc (dSSc) or limited SSc (lSSc)21, combined the EUSTAR (European Scleroderma Trial and Research Group) criteria for very early diagnosis of SSc (VEDOSS)22 or presented SSc sine scleroderma. These patients were supposed to be autonomous, aged between 18 to 80 years, and with the ability to understand Portuguese and to grant informed consent. Pregnant women were excluded.
To test the reliability of the SHAQ, a smaller group of patients was also randomly selected to complete, a second time, the measurement instrument one month after the previous consultation.
The study was approved by the Ethics Committee of the Regional Health Authority of the Centre (ARSC 14/2020) and by the Ethics Committee from one of the main hospital centres (CHTV 05/16/09/2021). We also obtained authorization from all heads of the five rheumatology departments involved. Each participant signed a written consent form before filling out the questionnaire.
Measurement instruments
Included patients were asked to complete sociodemographic, lifestyle, and clinical information, Portuguese versions of the generic questionnaires to measure health status (SF-36v2) and quality of life (EQ-5D-5L), as well as the University of California Los Angeles Scleroderma Clinical Trial Consortium Gastrointestinal Tract Instrument (UCLA GIT 2.0) and the SHAQ.
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Regarding the sociodemographic variables, we collected data from sex, age, marital and employment status, and years of education. Also, smoking and alcoholism were proxies for lifestyle variables. Lastly, the clinical variables measured were the SSc subset classification, disease duration since diagnosis, 2013 ACR/EULAR classification criteria, and organ involvement.
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The Short Form Health Survey (SF-36v2) is a generic instrument to measure the perception general population individuals have regarding their health status, on a scale from 0 (death) to 100 (perfect health status).23 It assesses eight dimensions (physical functioning [PF], bodily pain [BP], role limitations due to physical health [RP], general health perception [GH], mental health [MH], role limitations due to emotional problems [RE], vitality [VT], and social functioning [SF]) and provides two component summary measures, a physical (PCS) and a mental one (MCS). In the case of the Portuguese version24, these summary measures are normalized to the Portuguese general population.
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The EuroQoL EQ-5D-5L is a generic preference-based quality of life questionnaire that measures five dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression).25 Each dimension has five levels of intensity. A visual analogue scale EQ-VAS also asks for self-perception of general health status. Portuguese utilities can be computed by an algorithm based on general public preferences26 and Portuguese norms are also available.27
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The UCLA-GIT 2.0 questionnaire is a recognized and reliable instrument to assess gastrointestinal (GI) symptoms in SSc patients and its impact on quality of life.28 Recently validated to the Portuguese population29, it measures eight HRQoL dimensions (reflux, distention/bloating, fecal soilage, diarrhea, social functioning, emotional wellbeing, and constipation) and has been used in several clinical trials of GI treatments in patients with SSc as an outcome measure.30,31 The total UCLA GIT score is calculated by averaging all the subscales, except the one for constipation, and ranges from 0 (best HRQoL) to 2.83 (worst HRQoL). The levels of GI severity symptoms used in this paper were described by the author.32
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The SHAQ is comprised of the HAQ-DI plus six additional VAS – Pain, Intestinal, Breathing, Raynaud’s, Finger ulcer, and Overall disease severity. The HAQ-DI contains 20 items and measures eight domains: (i) dressing and grooming, (ii) arising, (iii) eating, (iv) walking, (v) hygiene, (vi) reach, (vii) grip, and (viii) activities.33 The answers for each question use a response scale from (0) without any difficulty to (3) unable to do. Intermediate response options are (1) with some difficulty and (2) with much difficulty. The highest score for any component question of each domain determines the score for that domain, exception for the necessity of aids or devices, where the score is automatically raised to two. A composite score is calculated by the average of the eight domains and ranges from 0 to 3, with a lower score indicating less impairment in function.
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Each additional VAS has a 1-week recall period, and it is represented by a line with 10 cm length. The value of the SHAQ VAS is multiplied by 0.3 to obtain the final score, ranging from 0 to 3 representing a minimum to maximum limitation, respectively.
Reliability
We tested the reliability of the Portuguese SHAQ version through internal consistency and intertemporal test-retest stability.
Internal consistency was tested through the score of Cronbach’s alpha coefficient, where accepted values should be between 0.70 and 0.90.19 The intertemporal stability was tested by the intraclass correlation coefficient (ICC) with two consecutive moments one month apart. We followed the criteria that defend that an ICC lower than 0.50 corresponds to a weak correlation, between 0.50 and 0.75 and between 0.75 to 0.90, respectively, to a moderate and good one, and a score higher than 0.90 corresponds to an excellent correlation.34
Validity
Construct validity tests included both structural validity and hypothesis testing with samples of sociodemographic and clinical variables. Finally, criterion validity was tested by comparing the HAQ-DI and SHAQ VAS scores with the scores obtained by the SF-36v2 and EQ-5D-5L.19
To test structural validity, we performed exploratory factor analysis based on principal components estimates with a previous assessment of the sampling adequacy via Kaiser-Meyer-Olkin (KMO) indicator and Bartlett’s test of sphericity. A KMO smaller than 0.50 or between 0.50 and 0.60 is considered unacceptable or poor, and if between 0.60 and 0.70, between 0.70 and 0.80, between 0.80 and 0.90 or higher than 0.90, seen, respectively, as fair, average, good or very good.35 The significance of the Bartlett sphericity test should be smaller than 0.001.36
The hypothesis testing was performed with known sociodemographic (sex, age group) and clinical variables groups, based on the distribution of each HAQ-DI variable. Student’s t-test was used for two independent variables and ANOVA for more than two independent variables.
To assess the criterion validity, we computed Pearson’s correlations between SHAQ items, SF-36v2 physical summary measure, and EQ-5D-5L index score. We followed Cohen’s rule37 from which correlations smaller than 0.30 are considered weak, between 0.30 and 0.50 are moderate, and higher than 0.50 are considered strong.
The statistical software used was SPSS v.28.