Table 8.

Adjusted probabilities of having sleep difficulties, by level of pain severity

DV	Pain severity	Adjusted probability	SE	95% LCL	95% UCL	P-value
Difficulty falling asleep	Matched control	0.10	0.01	0.09	0.12	–
	Mild	0.19	0.02	0.16	0.23	<0.0001
	Moderate	0.27	0.02	0.23	0.32	<0.0001
	Severe	0.30	0.03	0.25	0.37	<0.0001
Waking up during the night and not being able to go back to sleep	Matched control	0.09	0.01	0.07	0.10	–
	Mild	0.14	0.01	0.11	0.17	<0.0001
	Moderate	0.22	0.02	0.19	0.26	<0.0001
	Severe	0.23	0.03	0.18	0.28	<0.0001
Waking up several times during the night	Matched control	0.09	0.01	0.07	0.11	–
	Mild	0.14	0.01	0.11	0.16	<0.0001
	Moderate	0.20	0.02	0.16	0.24	<0.0001
	Severe	0.22	0.03	0.17	0.28	<0.0001
Poor sleep quality	Matched control	0.09	0.01	0.07	0.10	–
	Mild	0.21	0.02	0.18	0.24	<0.0001
	Moderate	0.28	0.02	0.24	0.33	<0.0001
	Severe	0.31	0.03	0.25	0.37	<0.0001
Sleep difficulties (presence of any of the above four difficulties)	Matched control	0.23	0.01	0.21	0.26	–
	Mild	0.40	0.02	0.36	0.44	<0.0001
	Moderate	0.51	0.02	0.46	0.56	<0.0001
	Severe	0.56	0.03	0.50	0.62	<0.0001

Notes: A generalized linear model, specifying a binomial distribution and a logit function, was conducted. The model adjusted for age, sex, education, annual household income, body mass index category, exercise behavior, smoking habits, alcohol consumption, and the Charlson Comorbidity Index.

Abbreviations: DV, dependent variable; LCL, 95% lower confidence limit; SE, standard error of the mean; UCL, 95% upper confidence limit.