Using Post-bronchodilator FEV1 is Better Than Pre-bronchodilator FEV1 in Evaluation of COPD Severity

Figures & data

Table 1.  Descriptive data for age, gender, spirometric values, BMI, MMRC dyspnea scale, ECOG performance status, Charlson co-morbidity score for the patients in the study showing mean and standard deviation

	Mean	SD
Age	71.9	10.8
Gender (male)	283/300 (94.3%)*
Pre-bronchodilator	59.5	21.1
FEV1 (% predicted)
Post-bronchodilator	63.4	21.2
FEV1 (% predicted)
BMI (Kg/m2)	23.6	4.1
MMRC dyspnea scale	1.8	0.9
ECOG performance status’ scale	1.1	0.8
Charlson co-morbidity score	2.4	1.8

FEV1 (% predicted): forced expiratory volume in one second (percentage of the predicted value), BMI: body mass index is the weight in kilograms divided by the square of the height in meters, MMRC: modified Medical Research Council dyspnea scale ranges from 0 (no dyspnea) to 4 (indicating that the patient is too breathless to leave home or becomes breathless when dressing or undressing), ECOG: Eastern Co-operative Oncology Group performance status ranges from 0 (fully active, without restriction) to 4 (completely disabled, totally confined to bed or chair). *Gender presented as ratio.

Table 2.  Univariate predictors of all cause mortality

	Survival	Mortality	P values
Age	71.3 ± 11.2	76.5 ± 5.7	0.007
Gender(male)	250/265(94.3%)	33/35(94.3%)	0.990
Pre-bronchodilator
FEV1 (% predicted)	60.5 ± 21.2	51.5 ± 18.3	0.018
Post-bronchodilator
FEV1 (% predicted)	64.7 ± 21.0	53.7 ± 19.6	0.005
BMI (Kg/m2)	23.9 ± 4.0	21.2 ± 4.3	<0.001
MMRC dyspnea scale	1.7 ± 0.9	2.6 ± 1.0	<0.001
ECOG performance status’ scale	1.0 ± 0.7	1.7 ± 1.0	<0.001
Charlson co-morbidity score	2.3 ± 1.6	3.3 ± 2.3	0.002
Severe AECOPD	26/255(10.2%)	8/24(33.3%)	0.004

FEV1 (% predicted): forced expiratory volume in one second (percentage of the predicted value), BMI: body mass index is the weight in kilograms divided by the square of the height in meters, MMRC: modified Medical Research Council dyspnea scale ranges from 0 (no dyspnea) to 4 (indicating that the patient is too breathless to leave home or becomes breathless when dressing or undressing), ECOG: Eastern Co-operative Oncology Group performance status ranges from 0(fully active, without restriction) to 4 (completely disabled, totally confined to bed or chair). AECOPD: acute exacerbation of COPD.

Table 3.  Multivariate analysis for pre and post-bronchodilator FEV1 associated with mortality, BMI, MMRC dyspnea scale, ECOG performance scale, and severe AECOPD adjusted by age, gender and Charlson co-morbidity score, presented as numbers of regression coefficient (p values)

	All cause mortality	Respiratory mortality	BMI	MMRC dyspnea scale	ECOG performance status’ scale	Severe AECOPD
Pre-bronchodilator FEV1 (% predicted)	0.05 (0.126)	0.04 (0.302)	-0.05 (0.233)	0.01 (0.335)	0.01 (0.151)	0.04 (0.293)
Post-bronchodilator FEV1 (% predicted)	-0.08 (0.008)	-0.10 (0.016)	0.09 (0.020)	-0.03 (<0.001)	-0.02 (<0.001)	-0.08 (0.039)

Figure 1: Kaplan-Meier survival curves for the four quartiles of the GOLD staging with post-bronchodilator percent predicted FEV1 (Panel A), and GOLD staging with pre-bronchodilator percent predicted FEV1 (Panel B). Survival differed significantly among the 4 stages for the GOLD with post-bronchodilator percent predicted FEV1 (p = 0.009), but not for the GOLD staging with pre-bronchodilator percent predicted FEV1 different staging criteria (p = 0.131) by the log-rank test.