More severe hypoxemia is associated with better subjective sleep quality in obstructive sleep apnea

BMC Pulmonary Medicine

Table 2 Correlation between PSQI-total score and age, body mass index, traditional parameters of polysomnography, sleep questionnaire and scales, and saturation-related variables (n = 156)

Variables	Correlation	Lower 95 %	Upper 95 %	p-value
Demographic data
Age(years)	0.209	0.054	0.355	0.009*
BMI (Kg/m²)	0.021	−0.137	0.177	0.796
Parameters of PSG
Total sleep time (min)	−0.235	−0.379	−0.081	0.003*
Sleep efficiency(%)	−0.195	−0.342	−0.039	0.015*
Sleep latency(min)	0.114	−0.044	0.267	0.156
Stage I (%)	0.050	−0.108	0.206	0.533
Stage II (%)	0.001	−0.156	0.158	0.992
Stage III (%)	−0.077	−0.231	0.081	0.339
Stage REM (%)	−0.016	−0.172	0.142	0.846
AHI (/hour)	−0.113	−0.265	0.045	0.162
Mean SpO2 (%)	0.016	−0.142	0.172	0.846
Mini SpO2 (%)	0.084	−0.075	0.238	0.300
ODI (/hour)	−0.085	−0.239	0.073	0.291
T90 (second/hour)	−0.069	−0.223	0.090	0.396
Arousal index (/hour)	−0.023	−0.179	0.135	0.778
PLMI (/hour)	0.146	−0.011	0.296	0.069
Questionnaire
ESS	0.274	0.122	0.413	<0.001*
SF-36 physical	−0.394	−0.519	−0.253	<0.001*
SF-36 mental	−0.445	−0.563	−0.310	<0.001*
CESD (n = 36)	0.372	0.049	0.624	0.026*
HADS-depression (n = 120)	0.257	0.081	0.418	0.005*
Saturation-related parameters
Median SpO2	−0.096	−0.249	0.062	0.235
Lowest 5 % SpO2	0.115	−0.043	0.267	0.154
Highest 5 % SpO2	−0.149	−0.299	0.008	0.063
Highest % SpO2 minus	0.051	−0.107	0.206	0.526
Median SpO2	0.051	−0.107	0.206	0.526
Median SpO2 minus Lowest 5 % SpO2	−0.161	−0.310	−0.004	0.045*

*p < 0.05
Abbreviations: BMI body mass index; REM rapid eye movement sleep; AHI apnea-hypopnea index; Mean SpO2 mean saturation of total time in bed; Mini SpO2 minimum saturation of total time in bed; ODI oxygen desaturation index; T90 time spent with saturation < 90 %; PLMI periodic leg movement index; ESS Epworth sleepiness scale; SF-36 Physical physical component score of short form 36; SF-36 Mental mental component score of short form 36; CESD center for epidemiologic studies depression scale; HADS-depression depression component of Hospital Anxiety and Depression Scale; median SpO2 the median value of saturation of total sleep time; Lowest 5 % SpO2 averaged value from the lowest 5 % saturation of total sleep time; Highest 5 % SpO2 averaged value from the highest 5 % saturation of total sleep time; Highest% SpO2 minus Medium SpO2 the difference between Highest 5 % SpO2 and Medium SpO2; Median SpO2 minus Lowest 5 % SpO2 the difference between Median SpO2 and Lowest 5 % SpO2

ISSN: 1471-2466