Sleep quality and covariates as predictors of pain intensity among the general population in rural China

Figures & data

Table 1 Sociodemographic characteristics of the participants (N=2052)

Characteristics		N	Percentage
Gender	Male	987	48.10
	Female	1065	51.90
Age (years)	18–25	37	1.80
	26–35	338	16.47
	36–45	503	24.51
	46–55	695	33.87
	56 and above	479	23.34
Ethnicity	Han	2042	99.51
	Non-Han	10	0.49
Education	Primary school or illiterate	814	39.70
	Middle school	925	45.10
	High school and above	313	15.30
Employment	Unemployed	797	38.89
	Employed in agriculture	891	43.42
	Non-agriculture	363	17.69
Income (yuan/year/person)	1992 or less	241	11.74
	1993–5523	513	25.00
	5524 or greater	1298	63.26
Marital status	Never married	145	7.07
	Married/cohabitating	1867	90.98
	Divorced/separated/widowed	40	1.95
Religion	Yes	205	9.99
	No	1847	90.01

Table 2 Psychological characteristics of the participants (N=2052)

Variable	Mean	SD
Sleep quality	7.28	2.55
Pain intensity	3.27	3.08
PHQ-9	3.64	3.92
GAD-7	2.73	3.56
Health status
Physical health	142.58	18.68
Mental health	117.17	21.44
Social health	85.12	18.76
Self-efficacy	27.09	4.36
Perceived stress	18.33	6.47

Abbreviations: GAD-7, 7-item Generalized Anxiety Disorder scale; PHQ-9, Patient Health Questionnaire Depression Module.

Table 3 Distributions of sleep quality and pain prevalence among rural Chinese people

Sleep quality (cm)	Participants (n)	Participants (%)	Pain-free participants (n)	Particpants in pain (n)	Four-week pain prevalence (%)
0–1.99	98	4.78	14	84	85.71
2–3.99	202	9.84	34	168	83.17
4–5.99	432	21.05	104	328	75.93
6–7.99	528	25.73	168	360	68.18
8–10	791	38.55	374	417	52.72

Table 4 Correlations between variables

Variable	Gender	Age	Edu	Income	Religion	P-health	M-health	S-health	Sleep	Pain intensity	Dep	Anx	Stress	Self-efficacy
Gender	1
Age	−0.03	1
Edu	−0.09**	−0.43**	1
Income	0.02	−0.06*	0.10**	1
Religion	−0.05*	−0.01	0.05*	0.00	1
P-health	−0.00	−0.18**	0.16**	0.03	0.10**	1
M-health	0.01	−0.05*	0.16**	0.04	0.08**	0.58**	1
S-health	0.01	−0.21**	0.30**	0.09**	−0.01	0.34**	0.47**	1
Sleep	−0.02	−0.11**	0.08**	0.03	0.05*	0.54**	0.40**	0.23**	1
Pain intensity	0.02	0.17**	−0.13**	−0.00	−0.09**	−0.58**	−0.37**	−0.17**	−0.30**	1
Dep	−0.02	−0.02	−0.079**	0.01	−0.09**	−0.50**	−0.57**	−0.29**	−0.47**	0.32**	1
Anx	0.04	0.00	−0.101**	0.00	−0.08**	−0.40**	−0.56**	−0.28**	−0.34**	0.26**	0.72**	1
Stress	−0.00	−0.17**	−0.021	−0.00	−0.07**	−0.38**	−0.52**	−0.30**	−0.26**	0.23**	0.59**	0.60**	1
Self-efficacy	0.03	−0.13**	0.049*	−0.01	−0.00	−0.08**	−0.18**	−0.19**	−0.04	0.03	0.08**	0.07**	0.150**	1

Notes:

** Significant at p=0.01;

* significant at p=0.05.

Abbreviations: anx, scores for anxiety symptoms scores; dep, scores for depressive symptoms; edu, highest level of education; m-health, mental health; p-health, physical health; s-health, social health.

Figure 1 The first ridge trace (K; including all the independent variables).

Figure 2 The second ridge trace (K; including the final 4 explanatory variables).

Table 5 Analysis of variance table for the final ridge regression model

	SS	df	MS	F-value	p-value
Regress	6215.88	4	1553.97	240.72	0.00

Note: Ridge parameter K=0.3.

Abbreviations: MS, mean square; SS, sum of squares.

Table 6 Predictors of pain intensity in the general population

	B	SE of B	β	t	p-value
Constant	13.60
Physical health	−0.06	0.00	−0.37	−24.98	0.00
Mental health	−0.01	0.00	−0.09	−5.73	0.00
Depressive symptoms	0.04	0.01	0.06	3.67	0.00
Sleep quality	−0.04	0.02	−0.03	−2.14	0.03

Abbreviations: B, coefficient value; SE, standard error; β, standardized coefficient.