Sleep disturbances are associated with increased pain, disease activity, depression, and anxiety in ankylosing spondylitis: a case-control study

Table 7 Stepwise multiple regression analysis of demographic, physiological, medical, and psychological variables in relation to PSQI

	Independent	B	Standardized coefficients	t	P	R² (%)
Predictors						39.5
	SDS	0.059	0.170	2.884	0.004
	SAS	0.128	0.287	4.759	0.000
	Nocturnal pain (VAS)	0.235	0.191	2.511	0.013
	Total back pain (VAS)	0.210	0.157	2.027	0.044

PSQI, Pittsburgh Sleep Quality Index; SAS, Self-rating Anxiety Scale; SDS, Self-rating Depression Scale, VAS, visual analogue scale.

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