Comparison of the lower limit of normal to the fixed ratio method for the diagnosis of airflow obstruction at high altitudes: a large cross-sectional survey of subjects living between 3000–4700 m above sea level

Table 2 Characteristics distribution of the individuals in each subgroup according to the two criteria

	FR+/LLN− group (n = 7, 0.2%)	FR−/LLN+ group (n = 143, 3.9%)	FR−/LLN− group (n = 3273, 88.4%)	FR+/LLN+ group (n = 279, 7.5%)	P value^a
	FR+/LLN− group (n = 7, 0.2%)	FR−/LLN+ group (n = 143, 3.9%)	FR−/LLN− group (n = 3273, 88.4%)	FR+/LLN+ group (n = 279, 7.5%)	FR−/LLN+ group vs. FR−/LLN− group	FR−/LLN+ group vs. FR+/LLN+ group
Age—years	73.0 (4.5)	30.1 (11.0)	38.6 (13.6)	47.0 (13.5)	< 0.001	< 0.001
BMI—kg/m²	25.5 (3.0)	23.0 (3.7)	24.1 (4.1)	23.9 (3.6)	0.895	0.041
Male—N	6 (85.7)	47 (32.9)	1641 (50.1)	134 (48.0)	< 0.001	0.001
History of tuberculosis	1 (14.3)	10 (7.0)	155 (4.7)	27 (9.7)	0.064	0.618
Household air pollution^b	3 (42.9)	108 (75.5)	1924 (58.8)	214 (76.7)	0.002	0.974
Exposure in the workplace^b	1 (14.3)	3 (2.1)	105 (3.2)	13 (4.7)	0.567	0.602
Smoking history	4 (57.1)	24 (16.8)	820 (25.1)	80 (28.7)	0.480	0.175
Symptoms^b	5 (71.4)	55 (38.5)	1251 (38.2)	160 (57.3)	0.356	0.282
CAT score^b ≥ 10	5 (71.4)	119 (83.2)	2538 (77.5)	246 (88.2)	0.011	0.488

Data are presented as the mean ± standard deviation or number %
BMI, body mass index; CAT, COPD assessment test; COPD, chronic obstructive pulmonary disease
^aAnalyses of differences using logistic regression. All models were adjusted for age, BMI, sex, risk factors for COPD, smoking status, CAT score, and respiratory symptoms
^bData missing for household air pollution (n = 15), exposure to dust or chemicals in the workplace (n = 36), respiratory symptoms (n = 80), and CAT scores (n = 80)

ISSN: 2047-783X