Moderate-to-Severe Obstructive Sleep Apnea and Cognitive Function Impairment in Patients with COPD

Figures & data

Table 1 Baseline Patient Characteristics

Variables	COPD+OSA (n=29)	COPD (n = 36)	p-value
Age, years	70.4±7.8	73.5±9.6	0.16
Male/Female	24/5	27/9	0.45
BMI, kg/m^2	22.3±4.7	23.1±4.7	0.86
Education, years	8.3±3.7	8.0±4.4	0.38
Smoking status			0.67
Current Smokers (n, %)	10 (34%)	9 (25%)
Former smokers (n, %)	14 (48%)	21 (58%)
Never-smokers (n, %)	5 (17%)	6 (17%)
Pack-years	48(32–76)	50(35–80)	0.65
Hypertension (n, %)	22(76%)	16(44%)	0.01
Diabetes (n, %)	10(27%)	8(28%)	0.98
IHD (n, %)	11(31%)	6(21%)	0.37
Cerebral infarction (n, %)	7(19%)	4(14%)	0.55
GOLD severity, I, II/III, IV	14/15	18/18	0.16
FEV1, % predicted	54.3±18.9	51.8±18.9	0.24
FVC, % predicted	79.1±22.9	80.6±18.0	0.78
FEV1/FVC, ratio	53.1±10.0	49.6±12.7	0.26
TLC, % predicted	84.8±17.9	82.7±18.6	0.67
RV/TLC, %	55.0±12.2	53.3±10.3	0.58
DLCO, % predicted	63.3±24.7	59.7±17.8	0.53
PaO2 (mmHg)	77.7±16.8	77.1±20.2	0.91
PaCO2 (mmHg)	43.2±5.1	42.6±7.0	0.75
Anxiety score	5(3–8)	5(2–7)	0.59
Depression score	4.5±4.3	3.6±4.0	0.41
ESS	5.2±4.0	4.4±3.9	0.42
CAT	21.7±4.7	18.2±5.5	<0.01
Beta-2 agonist use, n (%)	18(62%)	22(61%)	0.94
Anticholinergic use, n (%)	21(72%)	27(75%)	0.81
Inhaled corticosteroid use, n (%)	14(48%)	19(53%)	0.72
Mini-Mental State Examination	23.5±3.2	25.5±2.9	0.01*
Risk for dementia. n (%)	19(66%)	11(31%)	<0.01
Mild cognitive dysfunction, n (%)	7(24%)	16(44%)	0.09
No cognitive dysfunction, n (%)	3(10%)	9(25%)	0.13

Notes: Data are expressed as mean±standard deviation, median and interquartile range, or count (percentage). *P<0.05 for all levels of cognitive function between the 2 groups according to Chi Squared test.

Abbreviations: OSA, obstructive sleep apnea; COPD, chronic obstructive pulmonary disease; BMI, body mass index; IHD, ischemic heart disease; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; GOLD, Global Initiative for COPD; RV, residual volume; TLC, total lung capacity; DLCO, diffusion capacity of the lung for carbon monoxide; PaO₂, arteria oxygen partial pressure; PaCO₂, arteria carbon dioxide partial pressure; ESS, Epworth Sleepiness Scale; CAT, COPD assessment test.

Table 2 Polysomnography Parameters

Variables	COPD+OSA (n = 29)	COPD (n=36)	p-value
TST, min	318±72	339±83	0.29
Sleep efficiency, %	72.1±13.5	68.9±11.9	0.31
Arousal index, events/h	30.1±14.6	20.0±10.4	<0.01
Sleep architecture, % TST
Stage N1	16.3±9.8	14.4±9.2	0.42
Stage N2	57.2±13.2	54.9±14.1	0.50
Stage N3	10.5±8.3	13.9±11.6	0.19
Stage R	15.9±11.3	16.8±11.9	0.76
AHI, events/h	29.3±11.4	7.6±4.1	<0.01
AI, events/h	5.2±7.1	4.6±6.9	0.73
HI, events/h	24.1±12.0	3.0±4.4	<0.01
Mean SpO2, %	92.9±3.1	93.6±2.6	0.42
Lowest SpO2, %	78.9±7.9	85.0±6.1	<0.01
TST90 (%)	17.3±15.7	7.8±14.6	0.01
ODI (≥3%), events/h	20.8±11.5	5.6±5.0	<0.01

Note: Data are expressed as mean ± standard deviation.

Abbreviations: OSA, obstructive sleep apnea; AHI, apnoea hypopnoea index; AI, apnea index; HI, hypopnea index; SpO₂, pulse oxygen saturation; TST, total sleep time; R, rapid eye movement; ODI, oxygen desaturation index with oximetry recording; TST90, percentage of total sleep time spent with oxyhemoglobin saturation below 90%.

Table 3 Possible Predictors of Risk of Dementia in Patients with COPD

	Total (n=65)	COPD+OSA (n=29)	COPD (n=36)
	OR (95% CI) p	OR (95% CI) p	OR (95% CI) p
Age, years	1.08 1.02–1.15 0.02	1.15 1.01–1.30 0.03	1.24 1.06–1.45 <0.01
Male sex	1.76 0.53–5.81 0.36	1.33 0.18–9.66 0.78	0.73 0.32–1.67 0.45
Education	0.45 0.26–0.79 <0.01	0.24 0.08–0.70 0.01	0.34 0.14–0.84 0.02
Pack-years	0.77 0.23–2.63 0.68	1.69 0.89–3.19 0.11	0.63 0.22–2.05 0.48
Hypertension	0.39 0.13–1.15 0.09	0.96 0.91–1.21 0.29	0.58 0.12–1.37 0.17
Diabetes	0.82 0.30–2.24 0.70	1.05 0.96–1.14 0.28	0.72 0.12–4.16 0.71
IHD	0.80 0.25–2.51 0.70	0.97 0.93–1.01 0.37	1.27 0.28–2.31 0.52
Cerebral infarction	0.39 0.11–1.37 0.14	0.48 0.06–3.63 0.48	1.02 0.98–1.06 0.29
FEV1, % predicted	1.01 0.98–1.04 0.42	0.98 0.94–1.02 0.30	1.04 0.99 −1.09 0.16
Anxiety	0.98 0.84–1.14 0.76	0.98 0.78–1.24 0.87	0.94 0.74–1.20 0.60
Depression	0.99 0.87–1.11 0.83	0.99 0.83–1.20 0.99	0.92 0.74–1.15 0.47
CAT	0.99 0.91–1.09 0.91	1.11 0.92–1.33 0.28	0.97 0.85–1.10 0.62
ESS	1.04 0.62–1.76 0.87	1.07 0.96–1.19 0.22	1.12 0.83–1.50 0.46
AHI	1.17 1.09–1.27 <0.01	1.18 1.03–1.34 0.02	1.19 0.95–1.50 0.16
ODI	1.26 1.13–1.40 <0.01	1.37 1.10–1.70 <0.01	1.23 0.97–1.50 0.09
Mean SPO2, %	1.07 0.89–1.28 0.47	0.94 0.68–1.29 0.70	1.11 0.87–1.42 0.40
Lowest SPO2, %	0.99 0.93–1.07 0.88	0.96 0.85–1.07 0.45	1.08 0.94–1.23 0.30
TST90	0.98 0.96–1.01 0.10	1.01 0.95–1.07 0.79	0.98 0.94–1.01 0.19
TST, min	0.99 0.97–1.03 0.73	0.94 0.78–1.12 0.47	0.96 0.82–1.13 0.62
Arousal index	1.03 0.94–1.12 0.59	1.04 0.97–1.11 0.25	1.06 0.99–1.13 0.11
Sleep efficiency, %	0.97 0.81–1.12 0.71	1.06 0.97–1.15 0.20	0.98 0.93–1.02 0.32
Stage N1, % TST,	1.02 0.81–1.35 0.59	1.68 0.89–3.19 0.11	1.03 0.98–1.08 0.30
Stage N2, % TST	0.96 0.90–1.16 0.79	1.03 0.86–1.19 0.91	0.98 0.85–1.13 0.80
Stage N3, % TST	0.98 0.92–1.07 0.17	0.98 0.95–1.01 0.29	0.96 0.89–1.04 0.36
Stage R, % TST	1.03 0.81–1.19 0.51	0.94 0.78–1.12 0.47	1.06 0.95–1.18 0.38
Adjusted analysis
	OR (95% CI) p	OR (95% CI) p	OR (95% CI) p
Age, years	1.10 1.01–1.21 0.04	1.26 1.05–1.50 0.01	1.23 1.04–1.46 0.01
Education	0.38 0.14–0.98 0.04	0.26 0.08–0.89 0.03	0.37 0.13–0.86 0.04
AHI	1.06 0.99–1.19 0.08	1.07 0.94–1.26 0.27	–
ODI	1.24 1.04–1.48 0.02	1.38 1.02–1.87 0.04	1.03 0.98–1.08 0.22
Hypertension	1.06 0.92–1.13 0.31	–	–

Abbreviations: COPD, chronic obstructive pulmonary disease; IHD, ischemic heart disease; FEV₁, forced expiratory volume in 1 s; CAT, COPD assessment test; ESS, Epworth Sleepiness Scale; AHI, apnea hypopnea index, ODI, oxygen desaturation index; SpO₂, pulse oxygen saturation; TST, total sleep time; TST90, percentage of total sleep time spent with oxyhemoglobin saturation below 90%.

Figure 1 (A) The comparison of MMSE scores among patients with different severities of OSA. *Versus patients with an AHI<15 events/h, p < 0.05. (B) The comparison of MMSE scores among patients with different severities of airflow obstruction.

Abbreviations: AHI, apnoea hypopnoea index; MMSE, Mini-Mental State Examination; GOLD, Global Initiative for COPD.