Which is more important: the number or duration of respiratory events to determine the severity of obstructive sleep apnea?

Figures & data

Table 1. Demographic characteristics of the study population.

Characteristics (n = 121)	Values
Male (number)	82
Female (number)	39
Height, cm	169.49 ± 8.599
Weight, kg	94 (min–max: 69–145)
BMI*, kg/m^2	32.5 (min–max: 22.1–53.7)

*BMI: body mass index.

Table 2. Relationship of MOAD, MMAD, MCAD, MTAD, MHD and polysomnographic sleep parameters.

	MOAD	MMAD	MCAD	MTAD	MHD
Number of awakenings	r = −0.295	r = −0.242	r = −0.078	r = −0.293	r = −0.246
	p = 0.001	p = 0.008	p = 0.392	p = 0.001	p = 0.007
Sleep latency	r = −0.105	r = −0.161	r = −0.106	r = −0.107	r = −0.065
	p = 0.252	p = 0.078	p = 0.249	p = 0.241	p = 0.477
Total sleep time	r = 0.263	r = 0.177	r = 0.193	r = 0.250	r = 0.166
	p = 0.004	p = 0.052	p = 0.033	p = 0.006	p = 0.069
Sleep efficiency	r = 0.351	r = 0.266	r = 0.187	r = 0.337	r = 0.255
	p = 0.000	p = 0.003	p = 0.040	p = 0.000	p = 0.005
REM latency	r = 0.009	r = −0. 177	r = 0.045	r = −0.007	r = 0.054
	p = 0.918	p = 0.053	p = 0.624	p = 0.942	p = 0.557
WASO*	r = −0.351	r = −0.249	r = −0.166	r = −0.340	r = −0.268
	p = 0.000	p = 0.006	p = 0.068	p = 0.000	p = 0.003
Duration of REM sleep (min)	r = 0.238	r = 0.204	r = 0.203	r = 0.217	r = 0.160
	p = 0.009	p = 0.025	p = 0.026	p = 0.017	p = 0.080
Duration of N1 Sleep (min)	r = −0.238	r = −0.229	r = −0.089	r = −0.229	r = −0.166
	p = 0.009	p = 0.011	p = 0.331	p = 0.012	p = 0.069
Duration of N2 sleep (min)	r = 0.421	r = 0.248	r = 0.172	r = 0.421	r = 0.228
	p = 0.000	p = 0.006	p = 0.059	p = 0.000	p = 0.012
Duration of N3 sleep (min)	r = −0.197	r = −0.025	r = 0.024	r = −0.222	r = 0.033
	p = 0.030	p = 0.788	p = 0.796	p = 0.014	p = 0.716
REM sleep (%)	r = 0.200	r = 0.162	r = 0.153	r = 0.180	r = 0.129
	p = 0.028	p = 0.077	p = 0.094	p = 0.048	p = 0.158
N1 sleep (%)	r = −0.308	r = −0.259	r = −0.136	r = −0.290	r = −0.221
	p = 0.001	p = 0.004	p = 0.138	p = 0.001	p = 0.015
N2 sleep (%)	r = 0.359	r = 0.169	r = -0.022	r = 0.375	r = 0.136
	p = 0.000	p = 0.063	p = 0.814	p = 0.000	p = 0.136
N3 sleep (%)	r = −0.256	r = −0.071	r = −0.027	r = −0.280	r = −0.004
	p = 0.005	p = 0.439	p = 0.772	p = 0.002	p = 0.967

*WASO: wakening after sleep onset.

Bold values indicate p < 0.05.

Table 3. Relationship of MOAD, MMAD, MCAD, MTAD, MHD and blood oxygen parameters.

	MOAD	MMAD	MCAD	MTAD	MHD
Mean oxygen desaturation	r = 0.578	r = 0.339	r = 0.230	r = 0.598	r = 0.219
	p = 0.000	p = 0.000	p = 0.011	p = 0.000	p = 0.016
Number of desaturation (≥2)	r = 0.282	r = 0.169	r = 0.096	r = 0.287	r = −0.115
	p = 0.002	p = 0.064	p = 0.293	p = 0.001	p = 0.210
Desaturation index (≥2)	r = 0.209	r = 0.086	r = 0.010	r = 0.230	r = 0.228
	p = 0.021	p = 0.350	p = 0.912	p = 0.011	p = 0.012
Number of desaturation (≥3)	r = 0.284	r = 0.164	r = 0.100	r = 0.288	r = −0.120
	p = 0.002	p = 0.073	p = 0.275	p = 0.001	p = 0.191
Desaturation index (≥3)	r = 0.193	r = 0.075	r = 0.009	r = 0.213	r = 0.240
	p = 0.034	p = 0.411	p = 0.920	p = 0.019	p = 0.008
Number of desaturation (≥4)	r = 0.397	r = 0.215	r = 0.143	r = 0.406	r = −0.029
	p = 0.000	p = 0.018	p = 0.118	p = 0.000	p = 0.754
Desaturation index (≥4)	r = 0.338	r = 0.161	r = 0.086	r = 0.359	r = −0.108
	p = 0.000	p = 0.078	p = 0.346	p = 0.000	p = 0.240
Number of desaturation (≥5)	r = 0.474	r = 0.266	r = 0.170	r = 0.487	r = 0.032
	p = 0.000	p = 0.003	p = 0.062	p = 0.000	p = 0.728
Desaturation index (≥5)	r = 0.415	r = 0.209	r = 0.109	r = 0.439	r = −0.042
	p = 0.000	p = 0.021	p = 0.234	p = 0.000	p = 0.650
Duration below SO2 95%	r = 0.050	r = −0.036	r = 0.023	r = 0.037	r = 0.059
	p = 0.589	p = 0.691	p = 0.806	p = 0.691	p = 0.521
Duration below SO2 90%	r = 0.417	r = 0.225	r = 0.181	r = 0.432	r = 0.116
	p = 0.000	p = 0.013	p = 0.047	p = 0.000	p = 0.205
Duration below SO2 85%	r = 0.524	r = 0.301	r = 0.174	r = 0.541	r = 0.142
	p = 0.000	p = 0.001	p = 0.056	p = 0.000	p = 0.120
MMS* (REM supin)	r = −0.299	r = −0.285	r = −0.131	r = −0.338	r = −0.024
	p = 0.013	p = 0.017	p = 0.284	p = 0.005	p = 0.847
MMS* (NREM supin)	r = −0.384	r = −0.360	r = −0.309	r = −0.399	r = −0.226
	p = 0.000	p = 0.000	p = 0.003	p = 0.000	p = 0.032
MMS* (REM non-supin)	r = −0.208	r = -0.085	r = 0.205	r = −0.224	r = 0.211
	p = 0.062	p = 0.453	p = 0.067	p = 0.044	p = 0.058
MMS* (NREM non-supin)	r = −0.289	r = −0.041	r = 0.053	r = −0.309	r = 0.062
	p = 0.003	p = 0.678	p = 0.592	p = 0.001	p = 0.531
MMS* (during all sleep)	r = −0.362	r = −0.169	r = −0.096	r = −0.387	r = 0.002
	p = 0.000	p = 0.066	p = 0.298	p = 0.000	p = 0.980

*MMS: Mean minimum saturation.

Bold values indicate p < 0.05.

Figure 1. Two patients with apneas and associated oxygen desaturation events with different characteristics. Patient A has longer apneas and deeper oxygen saturation drops, but as they occur more seldom. Patient B has shorter apneas and shallower oxygen saturation drops occurring more frequently and therefore also higher AHI.