Graphic analysis of flow-volume curves: a pilot study

BMC Pulmonary Medicine

Table 3 Correlation between new graphic parameters and selected variables

	Ao		AR		Ao/FVC		Ao/AR		Ao/PEF		PEF/(Xp-FVC)		0.25/ 0.75 V
	r ^a	P	r ^a	P	r ^a	P	r ^a	P	r ^a	P	r ^a	P	r ^a	P
RV/TLC	0.674*	0.001	−0.824*	<0.001	0.806*	<0.001	0.718*	0.001	0.780*	<0.001	−0.585*	0.004	−0.286	0.197
SGRQ	0.171	0.447	−0.432	0.065	0.422	0.072	0.388	0.101	0.408	0.083	−0.057	0.802	0.108	0.631
6MWD	−0.013	0.956	0.488*	0.034	−0.398	0.092	−0.618*	0.005	−0.581*	0.009	0.336	0.126	−0.097	0.667
CAT	0.161	0.475	−0.342	0.152	0.382	0.106	0.331	0.167	0.308	0.200	−0.035	0.876	−0.007	0.976

Abbreviations: Ao area of concavity, AR area of rectangle, FVC forced vital capacity, PEF peak expiratory flow, Xp the lung volume at peak expiratory flow, 0.25/0.75 V ratio of volume at 75 and 25 % peak expiratory flow, RV residual volume, TLC total lung capacity, SGRQ St. George’s respiratory questionnaire, 6MWD 6-min walking distance, CAT the chronic obstructive pulmonary disease assessment test
^a r: Pearson’s correlation coefficient, adjusted for age, BMI and smoking
*P-value < 0.05

ISSN: 1471-2466