Development and validation of a self-administered systemic sclerosis questionnaire (SySQ)

Objective. To develop a self-administered systemic sclerosis questionnaire (SySQ) covering condition-specific functional limitation and symptoms. Methods. An initial item pool was generated by open patient interviews. A p reliminary questionnaire was devised using 62 systemic sclerosis (SSc; scle roderma) patients. Factor analysis was used for further selection and group ing of items into distinct scales. The retrieved scales were tested for int ernal consistency and test-retest reliability. Spearman's rank correlation and Wilcoxon's rank sum test were used to examine hypothesized associations of the SySQ with various clinical and laboratory features. Results. Altogether 32 SySQ items were selected and aggregated into 12 scal es addressing 'pain', 'stiffness', 'coldness', 'complex functions', 'streng th of hands', 'rising', 'walking', 'shortness of breath', 'upper airway sym ptoms', 'eating', 'swallowing' and 'heartburn/regurgitation'. Internal cons istency ranged from 0.93 ('complex functions') to 0.73 ('heartburn/regurgit ation'); Spearman's correlation coefficient for test-retest reliability ran ged from 0.93 to 0.73 (P < 0.001). While the scales were associated with co rresponding functional impairments, there was generally less association wi th morphological impairments. Conclusion. The SySQ is a valid and reliable condition-specific measure in patients with SSc. Individually applicable scales cover a wide spectrum of general and organ-specific SSc symptoms and functional limitation. After fu rther validation with respect to its ability to measure change, it may be u sed in clinical, health services and epidemiological research.