Systemic sclerosis (SS) or scleroderma is a rheumatologic disorder which mainly affects women, leading to vasculopathy, autoimmunity and fibrosis of the skin and visceral organs.1 During its initial stage, progressive, vascular dysfunction predominates and involves organs such as the skin, lung, heart, muscles, tendons, digestive tract, kidney and general health status.2 Many methods have been proposed for the measuring of SS activity, prognosis and assessment of therapeutic response, but few assess functionality. The speed of disease progression is highly varied for each individual and functionality is the main indicator of systemic improvement or impairment. The disability index of the Health Assessment Questionnaire (HAQ) is a tool which predicts survival. Although the HAQ is used in SS, it was designed for patients with rheumatoid arthritis. Its adaptation to SS (scleroderma Health Assessment Questionnaire) bears little correlation to disease severity.3 In 1998, a functionality scale was designed in England, but the patients qualified their disability as considerably higher than their therapist and it was not used.4 Another test refers solely to hand mobility in sclerodermia or the HAMIS Test.5 In view of this situation Ruof et al.6 designed a self-administered functionality questionnaire for SS (Systemic Sclerosis Questionnaire [SySQ]), which assesses the difficulty in carrying out everyday life activities and the intensity and frequency of symptoms with the highest functional impact in SS. This instrument was originally designed in German and has been validated into other languages, but not into Spanish. Scales were recently published for SS assessment but no functionality scale was specifically included for SS,7 and it was therefore our objective to validate the SySQ functionality scale transculturally in Mexican patients with SS and assess its relationship with the HAQ disability scale, disease severity and quality of life.

We conducted an observational analytical study in the Internal Medicine Department of the Specialities Hospital of the La Raza Medical Centre, of the Mexican Social Security Institute. We included all patients of a cohort diagnosed with SS, according to the criteria of the American College of Rheumatology of 1980 and confirmed in their classification with the American College of Rheumatology and the European League Against Rheumatism of 2013,8 who knew how to read and write and who signed the consent form. Excluded patients were those with syndromes overlapping clinical evaluation, mixed connective tissue disease, comorbidities affecting quality of life which were different from SS or those with impediments to questionnaire response. The protocol was approved by the local research and research ethics committee, registered with number R-2010-3501-40.

Phase 2. Application of the Questionnaire and Assessment of the Psychometric Measurements

In phase 2 we included 70 consecutive patients in follow-up visits out of a cohort of 210 patients with SS. The SySQ functionality self-administered questionnaire (Fig. 1) was administered, and adjusted with corrective questions which are shown and explained in Fig. 2. The disability self-questionnaire (HAQ) was applied, as was SF-36 quality of life quesionnaire,10 and the Medsger11 severity index. The latter took into account laboratory and imaging studies which had been taken no more than 3 months after the appointment date.

Fig. 1.

Mexican version in Spanish of the self-administered functionality scale of the Systemic Sclerosis Questionnaire.

Score. First. 32 scores were obtained in 3 domains. We chose the highest score for each domain (11 responses to ability, 12 to intensity and 9 to frequency). Initial scores were therefore reduced to 3. Second. To avoid confusions in low scores (0 and 1) a requirement was made to look at the corrective questions, as described in the section on Material and method. Third. The mean of the 3 values of the domains was calculated: (a) abilities, (b) intensity, and (c) frequency. This will be the final score of the SySQ questionnaire. Interpretation: 0=no difficulty or no symptoms; 1=slight difficulty, presences of mild symptoms and/or on some occasions; 2=serious difficulty, moderate symptoms and/or symptoms present frequently, and 3=incapacity, strong or intense symptoms which always present.

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Fig. 2.

Corrective questions for the version into Spanish of the Systemic Sclerosis Questionnaire.

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The final version of the translated questionnaire was assessed by 3 interviews with each patient: initially by 2 different interviewers to assess interobserver reproducibility and 14 days later by the first interviewer to assess intraoberver reproducibility. The SySQ questionnaire responses from the first interview were taken for internal consistency analysis using Cronbach's alpha. Reproducibility was assessed by taking into account all the occasions when the Cohen kappa test was performed. To relate the SySQ self-administered questionnaire with scales which could affect functionality, we calculated Spearman's coefficient with the HAQ disability scale and with Medsger's disease severity scale as a good indicator of specific damage to organs.12 We used the SF-36 quality of life questionnaire proposed as the appropriate one for this variable related to health in sclerodermia in a meta-analysis.13,14

We included 70 patients with SS, of 51.32±11.95 (17–78) years of age, 65 (93%) women, 45 (64.3%) of whom presented with the diffuse cutaneous variety, and 25 (35.7%) with limited cutaneous type, 5(7%) of them without dermal involvement or “sine sclerodermia”.17,18 Their evolution was 7 (.5–40) years (Table 1). The organs most frequently involved were skin (93%), vascular (77%) and gastrointestinal (77%) system; the least affected was the kidney (8.5%) (Table 1).

Each of the 3 domains of SySQ were affected to some extent in around 70% of cases. Functionality (SySQ) was most frequently affected in the capacity for pressure or in reaching (82.9%) and less regularly when walking (57.1%); the total score was 1.66 (.6–3.0) (Table 2). Frequency of symptoms was high in 10% of patients and in 58.5% to a lesser extent, and for this reason was the domain with the highest score (2.1–3). Although ability to undertake daily life activities affected 70% of the patients, this was to a very low degree, and obtained the lowest score (1.0–3) (Table 2). The internal consistency was as good as the original tool, since Cronbach's alpha was .96 for the total of the tool and in the original article Cronbach's alpha was .93. We observed good reproducibility of the baseline test in duplicate on the first day and assessed by different researchers (Cohen kappa .911) and a second test with a 2-week interval by the same researcher (Cohen kappa of .618).

Seventy percent (70%) of the patients included manifested affected functionality, mainly classified as “with some difficulty”, and the symptoms which limited their functionality were mostly “of moderate intensity” and “often” in frequency (Table 2).

The HAQ disability questionnaire uses a total score range from 0 to 3, similar to SySQ. With HAQ we obtained a total score of a little less than that obtained with SySQ (1.0–2.8). The 8 domains of the HAQ scale were affected in 58%–65% of the patients, and with a mild disability median (Table 3). The abilities domain of the SySQ scale also had a median in the range described as slight difficulty on carrying out everyday activities (Tables 2 and 3). Spearman's correlation coefficient between the HAQ and SySQ scales was moderate (r=.573, P=.0001).

We use the SF-36 (best 0-worst 100) questionnaire to analyse quality of life. In the physical domain we found 35.9 (2.8–82.5). The domain which most affected patients was body pain (98.4%; 45.0–100), followed by physical role (45.7%; .0–100) (Table 4). The mental domain affected 45% (9.3–90.8), vitality and mental health 100% of patients (50.10–100 and 48.10–96, respectively), and the emotional role affected 75.7% (3.3, 0–100) (Table 4).

The Spearman correlation was inverse between HAQ and the mental domain of the SF-36 (r=−.390, P=.001) and the physical domain of the SF-36 (r=−.620, P=.0001). The relationship was also inverse between the functionality SySQ scale and the mental domain of the SF-36 (r=−.435, P=.0001) and the physical domain of the SF-36 (r=−.680, P=.0001) (Table 5)

The SySQ correlation was moderate with the severity of the Medsger disease in the tendon (r=.458; P<.0001), and adequate for the lung, heart, vascular and muscular system (Table 5).

The degree of limitation of everyday life SySQ activities with the overall Medsger severity scale had a moderate to good correlation (r=.563, P<.0001), which shows that the degree of dysfunction in everyday activities has a direct correlation with the degree of involvement to organs in SS. Analysis by domains with the best correlation was the tendon and the intensity of the Raynaud phenomenon (r=.401, P<.003) (Table 5).

The Spanish version of the functionality questionnaire of systemic sclerosis (SySQ) proved to be valid and reliable for Mexican patients with SS, using a methodology for transition and transculturation which is reproducible and reflects to some extent the severity of organ involvement.

In contrast to other rheumatic diseases, few questionnaires have been designed for patients with SS: As a result, functional limitation in these patients has been measured in clinical trials by the HAQ-DI disability index, a tool developed to measure disability in patients with rheumatoid arthritis. Other tools have been developed and validated, the majority focusing on specific organs involved in the SS.10,11 This tool was previously published by our group as a summary presented in a congress,19 and later translated and validated into Portuguese and Italian.20,21 In Mexico there are no specific tools in the Spanish language to assess functionality in these patients.

Ruof et al.6 developed the questionnaire in German, covering general symptoms, in addition to gastrointestinal, cardiopulmonary and musculoskeletal ones. We assessed the SySQ, HAQ and SF-36 scales in order to find the differences and similarities on classifying the ability of patients to undertake everyday activities and the relationship with the damage to different organs. We found there was a good relationship between functionality and the severity of the Raynaud phenomenon, because as this is one of the initial signs of the disease it represents an impact from the beginning of SS. Also with tendon involvement, which usually appears during the progressive course of the disease. Other domains which were statistically significant in the relationship between functional status and severity of the disease were muscular, cardiac and pulmonary signs as a direct link between functionality and organicity assessable through the SySQ questionnaire.

In our study, the questionnaire translated into Spanish proved to be reproducible, and usable in the Mexican population. The validity and transcultural adaptation of the original tool was achieved for application to the Mexican population.

In our study we found a similar spectrum of patients to those found in previous studies where functionality indexes for SS were tried, although the tools used were not specific to this disease.5–7

The importance of our study is based on the objective data provided by the SS clinic of our hospital for a comprehensive assessment of the patients and this afforded us the necessary elements for correct application of the severity indexes.

It is important to consider that the questionnaire does not directly assess the Raynaud phenomenon or renal involvement but the presence of pain is an indirect detail demonstrating the existence of this vascular phenomenon and renal involvements is infrequent in the Mexican population.22 Furthermore, the psychological sphere of the patient has an effect on the self-appreciation of their abilities to carry out daily life, frequency and intensity of symptoms, with consequent greater or lesser appreciation of the same. The psychological area is not considered in the SySQ, and could therefore be complemented with other tools which are able to identify this concern.

The Spanish version of the SySQ questionnaire is valid, reliable, reproducible and accurate for the assessment of functionality in the Mexican population with SS. Our Spanish version of the self-administered SySQ functionality questionnaire had a coherent and inverse relationship with the HAQ disability scale, and with the physical and mental sections of the SF-36 quality of life scale. It also proved to be more closely related to the severity of the involvement of the tendon and peripheral vascular system in SS: The construction of new and better tools are required to allow us to assess not just the severity of symptoms but also the activity and chronicity of SS. The assessment of functionality in SS many also be an indirect indicator of treatment response.

The authors have no conflicts of interests to declare