. 2013 Sep 30;9:1483–1494. doi: 10.2147/NDT.S50763

Table 3.

Univariate nonparametric correlations between questionnaires, and age and PSG parameters

	FSS⁴		MFIS²		ESS²⁰		PSQI²⁴
	Spearman’s rho	Significance (P)	Spearman’s rho	Significance (P)	Spearman’s rho	Significance (P)	Spearman’s rho	Significance (P)
All patients
Scale
FSS			*0.742*	*<0.0001*	0.289	<0.0001	*0.488*	*<0.0001*
MFIS	*0.742*	*<0.0001*			*0.382*	*<0.0001*	*0.520*	*<0.0001*
ESS	0.289	<0.0001	*0.382*	*<0.0001*			0.202	0.006
PSQI	*0.488*	*<0.0001*	*<0.520*	*<0.0001*	0.202	0.006
PSG
AHI	0.098	0.065	0.077	0.136	0.047	0.457	0.132	0.031
SpO2% min	−0.047	0.374	−0.025	0.634	0.018	0.783	−0.078	0.207
Sleep efficacy	−0.005	0.921	0.010	0.839	0.078	0.219	−0.065	0.290
NREM-3/4	−0.036	0.503	−0.002	0.970	−0.096	0.131	−0.120	0.051
Awakening	0.098	0.068	0.158	0.002	0.176	0.005	0.278	<0.0001
Arousal index	0.038	0.481	−0.059	0.257	−0.056	0.382	−0.052	0.400
Sleep latency	0.053	0.321	0.006	0.909	−0.065	0.306	0.063	0.304
Age	−0.220	<0.0001	−0.152	0.003	−0.116	0.067	−0.120	0.050
Untreated SRBD patients
Scale
FSS			*0.686*	*<0.0001*	0.213	0.015	*0.480*	*<0.0001*
MFIS	*0.686*	*<0.0001*			*0.387*	*<0.0001*	*0.469*	*<0.0001*
ESS	0.213	0.015	*0.387*	*<0.0001*			0.225	0.021
PSQI	*0.480*	*<0.0001*	*0.469*	*<0.0001*	0.225	0.021
PSG
AHI	0.092	0.198	0.065	0.343	0.113	0.185	0.076	0.352
SpO2% min	−0.035	0.622	0.005	0.940	−0.034	0.689	−0.006	0.943
Sleep efficacy	−0.006	0.929	0.076	0.268	0.076	0.374	−0.046	0.576
NREM-3/4	−0.020	0.776	0.049	0.478	−0.127	0.137	−0.142	0.083
Awakening	0.061	0.392	0.120	0.080	0.152	0.075	0.253	0.002
Arousal index	0.083	0.244	−0.047	0.492	−0.052	0.542	0.073	0.377
Sleep latency	0.037	0.608	−0.019	0.781	−0.005	0.953	0.021	0.802
Age	−0.199	0.005	−0.142	0.037	−0.157	0.064	−0.026	0.754
Treated SRBD patients
Scale
FSS			*0.830*	*<0.0001*	0.192	0.176	*0.447*	*<000.1*
MFIS	*0.830*	*<0.0001*			*0.356*	*0.012*	*0.546*	*<000.1*
ESS	0.192	0.176	*0.356*	*0.012*			0.131	0.403
PSQI	*0.447*	*<0.0001*	*0.546*	*<0.0001*	0.131	0.403
PSG
AHI	0.044	0.677	0.080	0.449	−0.084	0.541	*0.328*	*0.005*
SpO2% min	−0.065	0.534	−0.160	0.125	0.107	0.437	−0.244	0.037
Sleep efficacy	−0.072	0.495	−0.161	0.124	−0.203	0.137	−0.117	0.323
NREM-3/4	0.150	0.150	0.108	0.303	−0.262	0.053	−0.036	0.763
Awakening	0.026	0.803	0.077	0.464	0.117	0.396	0.138	0.246
Arousal index	−0.182	0.080	−0.260	0.012	0.058	0.672	−0.282	0.016
Sleep latency	0.102	0.332	0.151	0.148	−0.085	0.539	0.151	0.201
Age	−0.171	0.102	−0.032	0.759	0.145	0.291	−0.157	0.184
PLMD and RLS patients
Scale
FSS			0.325	0.219	0.303	0.271	0.089	0.783
MFIS	0.325	0.219			0.272	0.291	0.452	0.163
ESS	0.303	0.271	0.272	0.291			−0.275	0.442
PSQI	0.089	0.783	0.452	0.163	−0.275	0.442
PSG
AHI	0.055	0.835	−0.040	0.875	0.240	0.353	0.444	0.148
SpO2% min	0.025	0.925	0.463	0.053	0.346	0.173	−0.407	0.189
Sleep efficacy	0.134	0.607	0.116	0.847	0.145	0.580	−0.221	0.491
NREM-3/4	0.060	0.819	*0.558*	*0.016*	0.359	0.157	0.355	0.257
Awakening	−0.477	0.053	0.013	0.959	0.349	0.170	−0.203	0.527
Arousal index	0.138	0.599	−0.159	0.528	−0.302	0.239	−0.323	0.305
Sleep latency	−0.020	0.938	0.046	0.856	*−0.623*	*0.008*	0.327	0.299
Age	−0.167	0.522	−0.092	0.717	0.036	0.890	*0.677*	*0.016*
Insomnia patients
Scale
FSS			*0.551*	*0.022*	0.474	0.063	0.267	0.523
MFIS	*0.551*	*0.022*			0.232	0.340	−0.115	0.753
ESS	0.474	0.063	0.232	0.340			0.453	0.221
PSQI	0.267	0.523	−0.115	0.753	0.453	0.221
PSG
AHI	−0.422	0.104	−0.019	0.937	−0.094	0.711	0.296	0.406
SpO2% min	0.406	0.119	0.303	0.194	0.210	0.403	−0.113	0.756
Sleep efficacy	−0.091	0.736	−0.074	0.755	0.054	0.831	0.006	0.986
NREM-3/4	0.367	0.162	−0.177	0.455	0.084	0.740	0.167	0.645
Awakening	0.138	0.610	0.054	0.823	0.265	0.289	0.099	0.786
Arousal index	0.055	0.841	0.135	0.569	0.061	0.811	*0.661*	*0.038*
Sleep latency	*0.610*	*0.012*	0.145	0.543	0.286	0.250	0.605	0.064
Age	−0.100	0.702	−0.091	0.694	−0.150	0.539	−0.258	0.445
Patients with MS, narcolepsy, hypersomnia
Scale
FSS			*0.914*	*<0.0001*	0.185	0.633	0.821	0.089
MFIS	*0.914*	*<0.0001*			−0.056	0.877	*0.900*	*0.037*
ESS	0.185	0.633	−0.056	0.877			−0.400	0.600
PSQI	0.821	0.089	*0.900*	*0.037*	−0.400	0.600
PSG
AHI	−0.471	0.143	−0.102	0.753	0.366	0.333	−0.600	0.400
SpO2% min	0.490	0.126	0.467	0.125	−0.527	0.145	0.800	0.200
Sleep efficacy	0.132	0.698	−0.133	0.681	0.557	0.119	0.000	1.000
NREM-3/4	−0.378	0.281	−0.482	0.133	−0.035	0.929	−0.800	0.200
Awakening	0.165	0.648	−0.264	0.432	0.235	0.543	0.600	0.400
Arousal index	0.049	0.894	0.209	0.537	−0.261	0.497	0.800	0.200
sleep latency	−0.049	0.894	0.055	0.873	−0.322	0.398	−0.400	0.600
Age	−0.058	0.857	−0.019	0.950	*0.809*	*0.005*	−0.300	0.624
Patients without sleep disorder
Scale
FSS			*0.890*	*<0.0001*	*0.754*	*0.019*	0.467	0.126
MFIS	*0.890*	*<0.0001*			0.538	0.135	*0.583*	*0.029*
ESS	*0.754*	*0.019*	0.538	0.135			0.185	0.661
PSQI	0.467	0.128	*0.583*	*0.029*	0.185	0.661
PSG
AHI	0.188	0.503	0.168	0.493	0.350	0.356	−0.137	0.640
SpO2% min	0.075	0.790	0.329	0.169	0.249	0.518	0.064	0.828
Sleep efficacy	−0.043	0.878	−0.044	0.858	−0.067	0.864	−0.368	0.196
NREM-3/4	*0.595*	*0.019*	*0.480*	*0.037*	0.506	0.164	0.146	0.618
Awakening	0.267	0.336	0.307	0.202	0.140	0.720	0.196	0.501
Arousal index	0.477	0.072	0.111	0.652	−0.034	0.932	0.192	0.512
Sleep latency	0.225	0.420	−0.175	0.473	0.059	0.881	0.363	0.202
Age	−0.229	0.412	−0.186	0.447	0.204	0.598	0.003	0.991
Parasomnia patients: due to small sample size, correlations could not be calculated.

Notes: Definition of the correlations of Spearman’s rho: very strong (0.9–1); strong (0.7–0.89); moderate (0.5–0.69); moderate to low (0.3–0.4.9); weak (<0.3). All significant values (P <0.05) with a Spearman’s rho greater or equal to 0.30 (low/moderate/strong/very strong correlation) are highlighted with bold and italic.

Abbreviations: AHI, apnea/hypopnea-index; ESS, Epworth Sleepiness Scale; FSS, Fatigue Severity Scale; MFIS, Modified Fatigue Impact Scale; MS, multiple sclerosis; NREM-3/4, non-rapid eye movement stage 3/4; PLMD, periodic limb movement disorder; PSG, polysomnographic; PSQI, Pittsburgh sleep Quality index; RLS, restless legs syndrome; Spearman’s rho, Spearman’s rank correlations; SpO2% min, minimal desaturation; SRBD, sleep-related breathing disorder.