Clinical and Radiological Features of COPD Patients Living at ≥3000 m Above Sea Level in the Tibet Plateau

Figures & data

Figure 1 Flow chart of the study.

Table 1 Demographic Characteristics and Risk Factors Relevant to COPD (n = 84)

Characteristics	Mean±SD or n (%)
Age	64.7±9.1
Gender
Male	50 (59.5)
Female	34 (40.5)
Height (cm)	162.4±7.8
Weight (kg)	61.2±11.4
BMI (kg/m^2)	23.1±3.7
Education
Primary school or lower	63 (75.0)
Junior middle school	3 (3.6)
Senior middle school	16 (19.0)
College or university	2 (2.4)
Altitude of residence (≥5 years)
3000–4000m	55 (65.5)
≥4000m	29 (34.5)
Residence
Urban	33 (39.3)
Suburb	5 (6.0)
Rural area or pastoral area	46 (54.8)
Profession (current or past)
Primary sector	49 (58.3)
Secondary sector	5 (6.0)
Tertiary sector	7 (8.3)
Quaternary sector	12 (14.3)
Unemployed	11 (13.1)
Smoking status
Current smokers	7 (8.3)
Former smokers	37 (44.0)
Never smokers	40 (47.6)
Smoking index (pack·year)^a	20.0 [10.0, 32.5]
Biomass exposure
Indoor biomass fuel use	74 (88.1)
Outdoor biomass fuel use	14 (16.7)
Tuberculosis history (ever-diagnosed)
Yes	19 (22.6)
No	59 (70.2)
Unknown	6 (7.2)
Recurrent respiratory infection in childhood	8 (9.5)
Premature
Yes	1 (1.2)
No	81 (96.4)
Unknown	2 (2.4)

Notes: Data are presented as Mean ± SD or n (%). ^aSmoking index was calculated in current and former smokers.

Abbreviations: SD, standard deviation; COPD, chronic obstructive pulmonary disease; BMI, body mass index.

Table 2 Clinical Characteristics of COPD Patients Living at High Altitude ≥3000 m Above Sea Level (n = 84)

Variables	Mean±SD or n (%)
Respiratory symptoms
Chronic cough	35 (41.7)
Chronic expectoration	34 (40.5)
Short of breath or wheezing	63 (75.0)
Dyspnea in daily life	70 (83.3)
CAT score	17.7±5.2
0–9	9 (10.7)
10–19	49 (58.3)
≥20	26 (31.0)
Comorbidities
Hypertension	39 (46.4)
Ischemic heart disease	0 (0.0)
Heart failure	15 (17.9)
Atrial fibrillation	1 (1.2)
Diabetes	2 (2.4)
Osteoporosis	1 (1.2)
Anxiety or depression	1 (1.2)
Spirometry function (post-BD)
FEV1/FVC %	56.96±9.68
FEV1%predicted	67.08±21.90
FVC %predicted	93.58±24.26
GOLD Stage
I	23 (27.4)
II	43 (51.2)
III	15 (17.9)
IV	3 (3.6)
Exacerbation in the past year
Frequency of exacerbation (/year)
0–1	68 (81)
≥2	16 (19)
Hospitalization related to exacerbation
0	44 (52.4)
≥1	40 (47.6)

Note: Data are presented as Mean ± SD or n (%).

Abbreviations: COPD, chronic obstructive pulmonary disease; CAT, COPD Assessment Test; BD, bronchodilator; FEV1, forced expiration volume in 1 second; FVC, forced vital volume; GOLD, Global Initiative for Chronic Obstructive Lung Disease.

Table 3 Pharmacology Therapy in COPD Patients Who Received Regular Medications in High Altitude ≥3000 m Above Sea Level

Pharmacological Treatment	N (%)
Inhaled SABA	3 (9.7)
Inhaled SAMA	2 (6.5)
ICS/LABA	28 (90.3)
LAMA	5 (16.1)
Oral theophylline	13 (41.9)
Oral acetylcysteine	1 (3.2)

Note: Data are presented as n (%).

Abbreviations: COPD, chronic obstructive pulmonary disease; SABA, short-acting β2-agonist; SAMA, short-acting muscarinic antagonist; ICS/LABA, inhaled corticosteroid plus long-acting β2-agonist; LAMA, long-acting muscarinic antagonist.

Table 4 Blood Routine Characteristics of COPD Patients Living at High Altitude ≥3000 m Above Sea Level (n = 84)

Variables	Mean±SD or n (%)
WBC count (×10^9/L)	5.77±1.93
RBC count (×10^12/L)	6.05±1.22
Hemoglobin (g/L)	177.7±30.5
Hematocrit (%)	54.3±9.6
Platelet count (×10^9/L)	204.4±93.9
Neutrophil%	63.1±9.8
Lymphocyte%	24.8±9.7
Eosinophil%	2.9±2.8
Eosinophil count
0–100 /μL	37 (44.0)
100–300 /μL	37 (44.0)
≥300/μL	10 (12.0)

Note: Data are presented as Mean ± SD or n (%).

Abbreviations: COPD, chronic obstructive pulmonary disease; WBC, white blood cell; RBC, red blood cell.

Table 5 Imaging Features of COPD Patients Living at High Altitude ≥3000 m Above Sea Level (n = 82)

Variables	Mean±SD or n (%)
Emphysema
LAA (%)	5.23 ± 7.39
No emphysema	58 (70.7)
Moderate emphysema	13 (15.9)
Severe emphysema	11 (13.4)
Airway analysis
WT/ (mm/m)	0.65 ± 0.23
LA/BSA (mm^2/m^2)	8.75 ± 6.02
WA/BSA (mm^2/m^2)	8.38 ± 4.77
WA%	50.85 ± 11.18
TDR	0.30 ± 0.08
Previous tuberculosis	37 (45.1)

Notes: Data are presented as Mean ± SD or n (%). WT was corrected by . LA and WA were corrected by BSA. BSA=0.0061×Height+0.0128×Weight-0.1529.

Abbreviations: COPD, chronic obstructive pulmonary disease; LAA, low attenuation area; WT, bronchial wall thickness; BSA, body surface area; LA, luminal area; WA, wall area; TDR, thickness-to-diameter ratio.

Table 6 Comparison of Clinical and Imaging Features Between COPD Patients Living at 3000–4000 m and ≥4000 m Above Sea Level

	Altitude		P value
	3000–4000 m (n = 55)	≥4000 m (n = 29)
Age (years)	65.6 ± 8.9	63.0 ± 9.5	0.208
Gender
Male	32 (58.2)	18 (62.1)	0.730
Female	23 (41.8)	11 (37.9)
BMI (kg/m^2)	22.8 ± 3.6	23.8 ± 3.8	0.273
Smoking status
Current smokers	5 (9.1)	2 (6.9)	0.940
Former smokers	24 (43.6)	13 (44.8)
Never smokers	26 (47.3)	14 (48.3)
Biomass exposure
Indoor biomass fuel use	49 (89.1)	25 (86.2)	0.731
Outdoor biomass fuel use	12 (21.8)	2 (6.9)	0.123
CAT score
0–9	6 (10.9)	3 (10.3)	0.582
10–19	30 (54.5)	19 (65.5)
≥20	19 (34.5)	7 (24.1)
Spirometry function (post-BD)
FEV1/FVC %	57.5 ± 10.1	55.9 ± 9.0	0.485
FEV1%predicted	67.3 ± 23.4	66.6 ± 19.0	0.883
FVC %predicted	92.6 ± 24.9	95.5 ± 23.3	0.606
GOLD Stage
I	14 (25.5)	9 (31.0)	0.961
II	29 (52.7)	14 (48.3)
III	10 (18.2)	5 (17.2)
IV	2 (3.6)	1 (3.4)
Emphysema
LAA (%)	6.86 ± 8.31	2.25 ± 3.91	0.001
No emphysema	33 (62.3)	25 (86.2)	0.039
Moderate emphysema	10 (18.9)	3 (10.3)
Severe emphysema	10 (18.9)	1 (3.4)
Airway analysis
WT/ (mm/m)	0.67 ± 0.25	0.63 ± 0.18	0.498
LA/BSA (mm^2/m^2)	9.61 ± 6.22	7.18 ± 5.36	0.080
WA/BSA (mm^2/m^2)	8.93 ± 5.23	7.37 ± 3.66	0.157
WA%	49.98 ± 12.25	52.45 ± 8.90	0.343
TDR	0.30 ± 0.09	0.31 ± 0.06	0.390
Previous tuberculosis on CT	24 (45.3)	13 (44.8)	0.968

Note: Data are presented as Mean ± SD or n (%).

Abbreviations: COPD, chronic obstructive pulmonary disease; BMI, body mass index; CAT, COPD assessment test; BD, bronchodilator; FEV1, forced expiration volume in 1 second; FVC, forced vital volume; GOLD, Global Initiative for Chronic Obstructive Lung Disease; LAA, low attenuation area; WT, bronchial wall thickness; BSA, body surface area; LA, luminal area; WA, wall area; TDR, thickness-to-diameter ratio.