Diagnostic accuracy of a pocket screening spirometer in diagnosing chronic obstructive pulmonary disease in general practice: a cross sectional validation study using tertiary care as a reference

Table 1 Demographics, smoking habit, presence of comorbid disorders and chronic treatment other than that for COPD according to final COPD diagnosis (N = 227)

Variables	All (N = 227)	COPD (n = 43)	Non-COPD (n = 184)	Statistics
Women (%)	115 (50.7)	17 (39.5)	99 (53.2)	χ2 = 2.711, P = 0.100
Age (years), mean ± SD	52.5 ± 6.8	53.6 ± 7.0	52.3 ± 6.7	t = 1.139, P = 0.256
BMI (kgm⁻²), mean ± SD	26.5 ± 4.2	26.5 ± 5.2	26.5 ± 3.9	t = 0.100, P = 0.921
Active smokers (%)	185 (84.9)	32 (84.2)	153 (85.0)	χ2 = 0.015, P = 0.902
Years of smoking, mean ± SD	30.6 ± 6.9	32.0 ± 6.4	30.3 ± 6.9	z = 1.641, P = 0.101
Cigarettes/day, mean ± SD	24.6 ± 9.1	24.4 ± 8.0	24.6 ± 9.2	z = 0.241, p = 0.809
Pack-years, mean ± SD	37.9 ± 17.4	39.1 ± 14.3	37.5 ± 17.5	z = 1.310, p = 0.190
Presence of comorbid disorders (%)	126 (55.5)	22 (51.2)	104 (56.5)	χ2 = 0.049, P = 0.825
Chronic treatment (%)	99 (43.6)	16 (37.2)	83 (45.1)	χ2 = 0.125, P = 0.724

χ2 chi-square test results, t result of Student’s t-test, z result of Mann-Whitney U test, SD standard deviation, BMI body mass index calculated as the ratio of body weight in kg and squared body height in meters

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