Obstructive sleep apnea and psychomotor vigilance task performance

Figures & data

Table 1 Baseline characteristics of study participants according to apnea hypopnea index categories

Variables	Apnea hypopnea index
	<5/hour n=18	5–15/hour n=19	15–30/hour n=10	>30/hour n=14
Age years, mean (SD)	42.9 (15.5)	52.0 (14.6)	47.0 (10.9)	52.0 (16.9)
Males, n (%)	9 (50)	11 (58)	7 (70)	11 (79)
BMI kg/m^2, median (Q1, Q3)*	32.0 (27, 39)	31.5 (26, 35)	32.6 (31, 36)	37.0 (33, 42)
ESS, mean (SD)	10 (4)	8.9 (6.5)	11.9 (6.1)	12.1 (5.6)
Neck circumference inches, median (Q1, Q3)*	15 (14, 17)	16 (14, 17)	16 (15, 18)	18 (17, 20)
Hypertension, n (%)	7 (39)	7 (41)	2 (20)	10 (71)
PSQI score, mean (SD)	8.2 (3.0)	8.8 (4.4)	6.8 (2.5)	8.1 (5.5)

Note:

* Represents quartile 1 and 3.

Abbreviations: BMI, body mass index; ESS, Epworth sleepiness scale; PSQI, Pittsburgh sleep quality index; SD, standard deviation.

Table 2 Baseline characteristics of study participants according to Epworth sleepiness scale categories

	ESS ≤9 n=25	ESS >9 n=36
Age years, mean (SD)	46.6 (17.5)	49.9 (13)
Males, n (%)	16 (64)	22 (61)
BMI kg/m^2, median (Q1, Q3)*	32.3 (29.0, 39.2)	33.2 (27.0, 38.0)
AHI, median (Q1, Q3)*	9 (5, 23)	13 (4, 29)
Neck circumference inches, median (Q1, Q3)*	16.0 (14.5, 17.5)	16.0 (15.0, 18.0)
Hypertension, n (%)	9 (37.5)	17 (48.6)
PSQI score, mean (SD)	8.1 (4.2)	8.2 (3.9)

Note:

* Represents quartile 1 and 3.

Abbreviations: AHI, apnea hypopnea index; BMI, body mass index; ESS, Epworth sleepiness scale; PSQI, Pittsburgh sleep quality index; SD, standard deviation.

Table 3 Psychomotor vigilance task performance by the apnea hypopnea index categories

PVT variables	AHI categories				P-value
	<5/hr n=18	5–15/hr n=19	15–30/hr n=10	>30 n=14
RT (ms)*	283 (37)	265 (47)	286 (49)	265 (34)	0.37
Fastest 10% RT (ms)*	209 (21)	194 (25)	209 (24)	200 (23)	0.18
Slowest 10% RT (ms)*	451 (164)	453 (182)	492 (184)	407 (88)	0.64
I/slowest 10% RT (ms)*	2.5 (0.45)	2.6 (0.61)	2.4 (0.69)	2.6 (0.41)	0.70
I/RT (ms)*	3.7 (0.42)	4.1 (0.59)	3.8 (0.54)	3.9 (0.42)	0.17
Lapses (RT >500 ms)**	0.9 (0.92)	0.97 (0.91)	1.4 (1.1)	0.68 (0.81)	0.34
False start (RT <100 ms)**	0.9 (1.3)	0.93 (1.0)	0.59 (1.0)	1.3 (1.1)	0.48

Notes:

* Log transformed;

** square root transformed; PVT variables represent back transformation after log/square root transformation. All PVT variable data is presented as mean (SD).

Abbreviations: AHI, apnea hypopnea index; I/RT, reciprocal response time; I/slowest, reciprocal of slowest response time; ms, milliseconds; PVT, psychomotor vigilance task; RT, reaction time; SD, standard deviation.

Table 4 Psychomotor vigilance task performance by Epworth sleepiness score categories

PVT variables	ESS categories		P-value
	≤9 n=25	<9 n=36
RT (ms)*	260 (27)	283.4 (48)	0.04
Fastest 10% RT (ms)*	198 (20)	204 (25)	0.27
Slowest 10% RT (ms)*	396 (100)	485 (181)	0.03
I/slowest 10% RT (ms)*	2.8 (0.42)	2.4 (0.57)	0.01
I/RT (ms)*	4.03 (0.41)	3.8 (0.55)	0.11
Lapses (RT >500 ms)**	0.6 (0.73)	1.2 (1.0)	0.03
False start (RT <100 ms)**	0.86 (1.1)	1 (1.1)	0.62

Notes:

* Log transformed;

** square root transformed; PVT variables represent back transformation after log/square root transformation; Bold P-values represent statistical significance. All PVT variable data is presented as mean (SD).

Abbreviations: ESS, Epworth sleepiness scale; I/RT, reciprocal response time; I/slowest, reciprocal of slowest response time; ms, milliseconds; PVT, psychomotor vigilance task; RT, reaction time; SD, standard deviation.

Table 5 Univariate regression models predicting psychomotor vigilance task variables

	Age (years)	BMI (kg/m^2)	ESS	PSQI	Arousal index	AHI (events/hour)
	R^2 (P-value)	R^2 (P-value)	R^2 (P-value)	R^2 (P-value)	R^2 (P-value)	R^2 (P-value)
RT* (ms)	0.13 (0.001)	0.03 (0.12)	0.04 (0.16)	0.11 (0.01)	0.04 (0.03)	0.02 (0.03)
I/RT* (ms)	0.09 (0.015)	0.01 (0.35)	0.03 (0.24)	0.14 (0.003)	0.04 (0.05)	0.02 (0.05)
Fastest 10% RT* (ms)	0.05 (0.09)	0.004 (0.61)	0.009 (0.47)	0.11 (0.009)	0.02 (0.11)	0.03 (0.04)
Slowest 10% RT* (ms)	0.18 (<0.001)	0.09 (0.005)	0.06 (0.07)	0.03 (0.25)	0.03 (0.19)	0.01 (0.12)
I/slowest 10% RT* (ms)	0.15 (<0.0001)	0.08 (0.01)	0.07 (0.07)	0.07 (0.06)	0.04 (0.02)	0.01 (0.17)
Lapses** (RT >500 ms)	0.15 (<0.0001)	0.16 (<0.0001)	0.07 (0.05)	0.01 (0.4)	0.003 (0.7)	0.007 (0.34)
False starts** (RT <100 ms)	0.08 (0.03)	0.02 (0.23)	0.001 (0.9)	0.001 (0.9)	0.01 (0.6)	0.01 (0.6)

Notes:

* Log transformed;

** square root transformed; Bold P-values represent statistical significance.

Abbreviations: AHI, apnea hypopnea index; BMI, body mass index; ESS, Epworth sleepiness scale; I/RT, reciprocal response time; I/slowest, reciprocal of slowest response time; ms, milliseconds; PSQI, Pittsburgh sleep quality index (global) score; RT, reaction time; SD, standard deviation.

Table 6 Multiple regression model

	Age (years)	BMI (kg/m^2)	ESS	PSQI	AHI (events/hour)	Sex
RT* (ms)	−0.003 (−0.01 to –0.002) 0.01	0.001 (−0.004–0.004)	0.005 (−0.001–0.01)	0.01 (0.0003–0.02) 0.055	−0.0005 (−0.0002–0.02)	–0.05 (−0.14–0.02)
Slowest 10% RT* (ms)	0.007 (−0.01–0.01) 0.005	−0.01 (−0.01–0.001)	−0.01 (−0.1 to −0.01) 0.06	0.01 (−0.01–0.03)	0.0005 (−0.002–0.001)	0.06 (0.21–0.09)
1/RT* (ms)	−0.002 (−0.004–0.0001) 0.045	−0.001 (−0.005–0.003)	−0.004 (−0.01–0.002)	−0.01 (−0.02 to −0.002) 0.03	0.0004 (−0.0004–0.001)	0.06 (−0.01 to −0.13)
Lapses** (RT >500 ms)	0.02 (0.01–0.03) 0.008	−0.04 (−0.07 to −0.01) 0.006	0.04 (−0.003 to −0.08) 0.07	0.01 (−0.05–0.07)	0.001 (−0.007–0.01)	0.12 (0.68–0.43)

Notes:

* Log transformed;

** square root transformed; Bold P-values represent statistical significance.

Abbreviations: AHI, apnea hypopnea index; BMI, body mass index; ESS, Epworth sleepiness scale; I/RT, reciprocal response time; ms, milliseconds; PSQI, Pittsburgh sleep quality index (global) score; RT, reaction time.