Table 6. Results of multivariate linear regression models.

Indicator	Model Ia			Model IIb
	βc	SEd	P value	βc	SEd	P value
Chronic diseases (against people with no chronic diseases at all)
Infectious disease	−9.41	1.66	0.0004	-	-	-
Cancer	−13.73	5.2	0.0351	-	-	-
Diabetes	−5.86	1.28	<.0001	-	-	-
Anemia	−4.08	2.51	0.1144	-	-	-
Mental disease	−28.03	3.58	<.0001	-	-	-
Heart disease	−10.7	1.9	<.0001	-	-	-
Hypertension	−4.69	0.87	<.0001	-	-	-
Cerebrovascular disease	−17.83	1.93	<.0001	-	-	-
Respiratory disease	−4.93	2.02	0.0210	-	-	-
Digestive disease	−4.54	1.28	0.0013	-	-	-
Genitourinary disease	−7.17	1.93	0.0008	-	-	-
Musculoskeletal disease	−5.9	0.95	<.0001	-	-	-
Other chronic disease	−9.07	1.21	<.0001	-	-	-
Co-morbidity (against healthy population)
No CD but health problems experienced during the two weeks before the survey	-	-	-	0.66	1.71	0.7027
One CD	-	-	-	−6.52	0.77	<.0001
Two CDs	-	-	-	−9.89	1.72	<.0001
Three or more CDs	-	-	-	−10.58	3.1	0.0018
Socio-demographic characteristics
Urban area of residence	0.84	1.65	0.0254	0.90	1.68	0.0325
Male	0.84	0.35	0.0226	0.81	0.34	0.0244
High school education or more	1.08	0.39	0.0097	1.02	0.39	0.0146
Discomfort experienced during the two weeks immediately before the survey	−4.89	0.86	<.0001	−5.22	1.59	0.0027
Age (against 65+)
15–44	10.82	0.93	<.0001	10.87	0.9	<.0001
45–64	5.65	0.79	<.0001	5.75	0.77	<.0001
Marital status (against those currently married)
Divorced	−1.01	1.29	0.4362	−1.06	1.31	0.42
Widowed	−1.61	0.77	0.0457	−1.58	0.738	0.0394
Never married	2.49	0.61	0.0003	2.42	0.61	<.0001
Other	1.83	1.43	0.2096	1.7	1.42	0.2399
Employment (against employed)
Retired	0.19	1.08	0.8601	0.31	1.1	0.7785
Unemployed	−1.83	1.55	0.0248	−1.98	1.55	<.0001
Student	0.01	0.72	0.9927	0.07	0.71	0.9276
Social medical insurance (against those with no social medical insurance)
Urban workers' medical insurance	−1.77	0.99	0.0842	−1.75	1.01	0.0935
Free medical service	2.82	3.08	0.0167	2.79	2.95	0.0097
Urban residents' medical insurance	−0.17	1.14	0.8808	−0.15	1.16	0.8959
New rural cooperative medical system	−0.52	1.46	0.7217	−0.54	1.51	0.7207
Other	0.55	1.55	0.7238	0.46	1.54	0.7691
Smoker (against lifelong nonsmokers)
Smoker	−0.77	0.48	0.1197	0.85	0.47	0.0790
Ex-smoker	−2.21	1.37	0.1170	−1.59	1.25	0.2150
Alcohol use (against those who have never drunk alcohol)
One or two times a week	−0.92	1.22	0.4545	−1.01	0.84	0.2386
More than three times a week	0.17	1.67	0.9184	−0.08	1.69	0.9625
Physical exercise (against those who never exercise)
No more than 6 times a week	1.98	0.62	0.0032	2.12	0.62	0.0019
More than 6 times a week	2.81	0.71	0.0005	2.95	0.69	0.0002
Constant	73.07	2.97	<.0001	72.90	1.76	<.0001
F Value	158.06	-	<.0001	767.49		<.0001
R-square	0.3			0.28
Total number of respondents in the model	10267			10267

Note: a: Model I, in which EQ VAS was the dependent variable, and 13 classes of chronic diseases and socio-demographic and health behavior variables were independent variables;

b: Model II, in which EQ VAS was the dependent variable, and co-morbidity and socio-demographic and health behavior variables were independent variables;

c: Regression coefficient (linear relationship) indicating the difference in EQ VAS score comparing each subgroup to the reference;

d: SE, standard error.