Table IV.

Cox regression analyses of variables associated with individual sleep disorders (insomnia, sleep apnea, and restless legs syndrome) in patients with prurigo nodularis and control patients

Outcome	Insomnia			Sleep apnea			Restless legs syndrome
Variables	aHR	95% CI	P value	aHR	95% CI	P value	aHR	95% CI	P value
Prurigo nodularis	1.77	1.48-2.12	<.005	1.51	0.93-2.44	.10	1.54	0.92-2.57	.10
Age, y
<30	0.86	0.61-1.21	.40	0.94	0.31-2.83	.92	0.40	0.11-1.41	.15
30-39	0.87	0.61-1.23	.43	1.59	0.79-3.20	.19	0.17	0.02-1.28	.09
40-49	1.11	0.84-1.46	.45	1.04	0.55-1.98	.91	0.34	0.11-1.03	.06
50-59	Reference	---	---	Reference	---	---	Reference	---	---
60-69	1.03	0.78-1.35	.85	0.48	0.24-0.99	.05	2.35	1.23-4.50	.01
70-79	1.06	0.79-1.43	.68	0.23	0.07-0.75	.02	1.19	0.52-2.69	.68
≥ 80	1.07	0.74-1.56	.71	0.43	0.10-1.85	.26	0.69	0.20-2.45	.57
Sex
Male	Reference	---	---	Reference	---	---	Reference	---	---
Female	1.07	0.90-1.29	.43	0.39	0.24-0.64	<.005	1.68	0.97-2.90	.06
Race
White	Reference	---	---	Reference	---	---	Reference	---	---
Black	1.35	0.73-2.47	.34	---	---	---	---	---	---
Asian	1.12	0.74-1.70	.59	0.86	0.26-2.85	.80	0.54	0.07-3.90	.54
Other	0.91	0.76-1.09	.30	1.07	0.67-1.72	.77	1.12	0.68-1.86	.66
Major depressive disorder	2.01	1.33-3.06	<.005	1.39	0.43-4.49	.59	5.67	2.53-12.7	<.005
Anxiety disorder	1.62	1.21-2.17	<.005	0.78	0.28-2.17	.64	0.80	0.29-2.23	.67
Iron deficiency anemia	---	---	---	---	---	---	1.25	0.39-4.05	.71
BMI, kg/m2
<25.0	Reference	---	---	Reference	---	---	Reference	---	---
25.0-29.9	0.72	0.58-0.90	<.005	0.42	0.15-1.16	.09	1.09	0.55-2.16	.80
≥30	0.86	0.66-1.13	.28	10.04	4.28-23.5	<.005	1.33	0.61-2.90	.47

Bold values denote statistical significance at the P < .05 level.

aHR, Adjusted hazard ratio; BMI, body mass index.