. 2013 Oct 9;13:945. doi: 10.1186/1471-2458-13-945

Table 5.

Spirometry results with PFT pattern classification based upon new-onset respiratory symptoms (N = 220)

	Mean NHANES % predicted (std)	Below LLN and symptoms N = 110 (%)	Below LLN and no symptoms N = 110 (%)	Adjusted prevalence ratio* (95% CI)**	*p-value*
	Median				*p-value*
FEV1	72.1 (21.5)	75 (68.2)	51 (46.4)	1.73 (1.11, 2.69)	0.015*
FEV1	74.0	75 (68.2)	51 (46.4)	1.73 (1.11, 2.69)	0.015*
FVC	81.7 (23.6)	61(55.5)	49 (44.6)	1.66 (1.0, 2.77)	0.051
FVC	80.0	61(55.5)	49 (44.6)	1.66 (1.0, 2.77)	0.051
FEV1/FVC ratio %	82.4 (0.09)	15 (13.6)	9 (8.2)	2.25 (0.542, 9.34)	0.264
FEV1/FVC ratio %	84.3	15 (13.6)	9 (8.2)	2.25 (0.542, 9.34)	0.264
FEF_25-75%	95.1 (39.1)	16 (14.6)	9 (8.2)	1.60 (0.50, 5.16)	0.431
FEF_25-75%	93.2	16 (14.6)	9 (8.2)	1.60 (0.50, 5.16)	0.431
Any abnormal parameter		82 (74.5)	64 (59.1)	1.62 (1.10, 2.39)	0.015*
Air-Flow pattern results**	Normal	28	45
	Obstructive^§	12	8
	Mild	3	0
	Moderate	4	3
	Severe	5	3
	Very severe	0	2
	Restrictive^§§	46	34
	FEV1<LLN^§§§	24	23

*Statistically significant at α = 0.05.

**Normal = FEV1 and FVC ≥ LLN and FEV1/FVC ratio ≥ LLN.

§Obstructive Spirometry Pattern = FEV1/FVC ratio < LLN.

Mild: FEV1% predicted > 80% ,Moderate: 50% < FEV1 < 80% predicted, Severe: 30%< FEV1 <50% predicted, Very Severe: <30% predicted [39,42].

§§Restrictive Spirometry Pattern = FEV1, FVC, and FEV1/FVC Ratio > LLN.

***Covariate adjustment for age, sex, race, smoking and educational status.

Adjusted prevalence ratios (PR), 95% confidence intervals, and Chi-square p-values for the association between report of respiratory symptoms and spirometry parameters below LLN.