Assessment of cognitive impairment in long-term oxygen therapy-dependent COPD patients

Figures & data

Table 1 Demographic characteristics of study subjects

	Regular-user LTOTD-COPD group	Nonuser LTOTD-COPD group	P-value
Age (years)	69.3±10.0	68.4±14.0	>0.05
Sex (M/F), n	15/6	13/11	>0.05
Education level (ES/HS), n	15/6	19/5	>0.05
FEV1	33±11.5	31.7±15.0	>0.05
FVC	36.9±8.5	32.8±15.4	>0.05
pH	7.4±0.5	7.3±0.6	>0.05
pO2	47.5±11.2	48.0±9.8	>0.05
pCO2	40.1±8.6	45.0±11.4	>0.05
SO2 (%)	83.2±7.9	82.5±7.9	>0.05
pO2 (using oxygen)	71.0±6.8	69.0±7.3	>0.05
pCO2 (using oxygen)	48.9±2.2	47.6±3.1	>0.05
SO2 (%) (using oxygen)	90.1±5.0	89±6.2	>0.05
Smoking (pack years)	39.95±20.9	40.12±15.1	>0.05
Number of hospitalizations in last year	1.6±1.0	2.8±2.8	>0.05
Number of emergency admissions in last year	2.8±4.3	5.8±10.4	0.011*

Notes: Data are presented as means ± SD, unless otherwise specified.

* There was a significant difference between the number of emergency admissions in the last year between the regular-user LTOTD-COPD group and the nonuser LTOTD-COPD group.

Abbreviations: M, male; F, female; ES, elementary school; HS, high school; FEV₁, forced expiratory volume in 1 second; FVC, force vital capacity; pO₂, partial oxygen pressure; pCO₂, partial carbon dioxide pressure; SO₂, oxygen saturation; LTOTD, long-term oxygen therapy-dependent.

Table 2 Reasons for poor compliance among nonuser LTOTD-COPD patients

Reasons	Frequency	Percentage
Financial problems causing difficulty in paying for electricity	8	33.3
Headache	10	41.6
Machine is noisy when operating	2	8.3
Machine breakdown	2	8.3
Not convinced of benefit of oxygen therapy	2	8.3
Total	24	100

Abbreviation: LTOTD, long-term oxygen therapy-dependent.

Table 3 The proportion of patients with cognitive impairment

Groups	MoCA (+), %	MMSE (+), %
Regular-user LTOTD-COPD group	36.8%	26.3%
Nonuser LTOTD-COPD group	70.8%	50%

Note: “+” indicates cognitive assessment test result is positive for cognitive impairment.

Abbreviations: LTOTD, long-term oxygen therapy-dependent; MMSE, Mini-Mental State Examination; MoCA, Montreal Cognitive Assessment.

Figure 1 Box plot of the MoCA scores for the two study groups.

Abbreviations: LTOTD, long-term oxygen therapy-dependent; MoCA, Montreal Cognitive Assessment.

Figure 2 Box plot of the MMSE scores for the two study groups.

Abbreviations: LTOTD, long-term oxygen therapy-dependent; MMSE, Mini-Mental State Examination.

Table 4 Mean values of MoCA and MMSE scores for our study groups

Cognitive test	Nonuser LTOTD-COPD	Regular-user LTOTD-COPD	P-value
MoCA	19.37±2.99	21.68±2.14	0.007
MMSE	23.75±2.63	25.89±2.79	0.014

Notes: Data are presented as means ± SD. P-values were calculated by Mann–Whitney U-tests.

Abbreviations: LTOTD, long-term oxygen therapy-dependent; MoCA, Montreal Cognitive Assessment; MMSE, Mini-Mental State Examination.

Table 5 Correlation between MoCA–MMSE score and clinical parameters

Cognitive test	Number of hospitalizations in last year	Number of emergency admissions in last year
MoCA
Correlation	−0.57	−0.39
P-value	<0.0001	0.01
MMSE
Correlation	−0.52	−0.40
P-value	<0.0001	0.007

Note: P-values calculated with Mann–Whitney U-test.

Abbreviations: MoCA, Montreal Cognitive Assessment; MMSE, Mini-Mental State Examination.