Table 2. Correlation between sleep quality and age, disease duration, disability, and quality of life in patients with systemic sclerosis.

	Sleep quality (PSQI)
	R	95%CI	p-value
Age	-0.09	-0.37 to 0.20	0.53
Disease duration	-0.03	-0.33 to 0.28	0.86
ESS-BR	-0.09	-0.37 to 0.20	0.55
SHAQ	0.52	0.26 to 0.70	<0.001
SF-12 PCS	-0.42	-0.63 to −0.14	0.003
SF-12 MCS	-0.43	-0.64 to −0.16	0.002

ESS-BR: Epworth Sleepiness Scale–Portuguese version; MCS: mental component summary; PCS: physical component summary; PSQI: Pittsburgh Sleep Quality Index; SF-12: 12-item short-form health survey; SHAQ: scleroderma health assessment questionnaire.