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

Table 6 Hierarchic multiple regression analysis of demographic, medical, and psychological variables in relation to PSQI

	Model 1		Model 2		Model 3		Model 4
	B	Pvalue	B	Pvalue	B	Pvalue	B	Pvalue
Age (years)	0.057	0.122	0.064	0.081	0.032	0.314	0.055	0.103
Gender (male)	0.738	0.108	0.098	0.823	-0.228	0.575	-0.435	0.292
Years of education	-0.583	0.011	-0.333	0.105	-0.266	0.181	-0.190	0.318
Student (yes)	-1.261	0.083	0.587	0.365	-0.805	0.203	-0.455	0.449
Employment (yes)	-1.068	0.078	-1.099	0.043	-0.638	0.225	-0.798	0.112
Married (yes)	0.174	0.788	0.168	0.769	0.010	0.985	0.011	0.984
ESR			0.007	0.535			0.009	0.399
CRP			-0.005	0.941			-0.022	0.706
Disease duration			-0.055	0.230			-0.052	0.214
Morning stiffness (minute)			0.001	0.919			0.001	0.904
Fingertip-to-floor distance (cm)			-0.011	0.481			-0.009	0.531
Overall assessment of health (VAS)			0.029	0.760			-0.039	0.658
Nocturnal pain (VAS)			0.267	0.012			0.258	0.009
Total back pain (VAS)			0.133	0.302			0.168	0.159
BASMI			-0.222	0.100			-0.149	0.233
BASDAI (VAS)			0.456	0.005			0.210	0.168
BASFI (VAS)			-0.067	0.595			-0.157	0.184
SDS					0.064	0.004	0.059	0.008
SAS					0.170	0.000	0.120	0.000
R² (%)	8.5		32.0		32.4		42.6
Adjusted R² (%)	6.7		28.0		30.6		38.9

Model 1 F = 4.756; P = 0.000; Model 2 F = 8.176; P = 0.000; Model 3 F = 18.290; P = 0.000; Model 4 F = 11.507; P = 0.000. BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; PSQI, Pittsburgh Sleep Quality Index; SAS, Self-rating Anxiety Scale; SDS, Self-rating Depression Scale; VAS, visual analogue scale.