Asthma COPD Overlap Syndrome on CT Densitometry: A Distinct Phenotype from COPD

Figures & data

Figure 1. A flowchart of this study.

Table 1. The characteristics of the subjects.

	COPD (N = 32)	ACOS (N = 39)
Age, mean ± SD (y)	63.6 ± 6.7	62.5 ± 7.2
Male/female (no.)	26/6	29/10
BMI, mean ± SD (kg/m^2)	23.7 ± 3.5	24.9 ± 3.6
Current or former mokers (no.)	28^a	31
Pack years, median (IQR)	29 (34)	26 (33)
GOLD class^*
Gold I	6 (19%)	7 (18%)
Gold II	9 (28%)	23 (59%)
Gold III	13 (41%)	6 (15%)
Gold IV	4 (13%)	3 (8%)

^*0.01< P <0.05 between the groups.

^aNon-smoke COPD patients all reported noxious particles or gases exposure in their work.

BMI = body mass index; IQR = interquartile range.

Table 2. The physiologic parameters of the subjects.

	COPD (N = 32)	ACOS (N = 39)
Pre-BD
FEV1, mean ± SD (L)	1.33± 0.56	1.40 ± 0.48
FEV1, mean ± SD (%pred)	50 ± 23	52±15
FEV1/FVC, mean ± SD (%)	50 ±12	52 ± 9
RV/TLC, mean ± SD (%)	58 ± 11	57 ± 9
Specific Raw, mean ± SD (kPa/s)	5.68 ± 3.26	4.76 ± 2.46
Post-BD
FEV1, mean ± SD (L)	1.43 ± 0.54	1.74± 0.52^*
FEV1, mean ± SD (%pred)	53 ± 21	65±17^*
FEV1 improvements (L)	0.10 ± 0.13	0.34 ± 0.14^†
FEV1 improvements(%pred)	3 ± 6	13 ± 6^†
FEV1/FVC, mean ± SD (%)	51 ±11	55 ±10
RV/TLC, mean ± SD (%)	55 ± 10	49 ± 10^*
Specific Raw, mean ± SD (kPa/s)	3.85 ± 1.96	2.94 ± 2.08
DLCO/VA, mean ± SD (%)	95 ± 38	101 ± 36

The values are expressed as means ± SDs.

^* 0.01 < P < 0.05 vs. patients with COPD.

^† P < 0.001 vs. patients with COPD.

COPD = chronic obstructive pulmonary disease; ACOS = asthma COPD overlap syndrome; FEV₁ = forced expiratory volume in one second; FVC = forced vital capacity; TLC = total lung capacity; RV = residual volume; R_aw = airway resistance; D_LCO = diffusing capacity for carbon monoxide; V_A = alveolar volume.

Table 3. A comparison of whole-lung CT measurements between the patients with COPD and ACOS.

	COPD	ACOS	P value (95% CI)
pre-BD
EI (%)	12.41 ± 8.89	8.12 ± 7.21	0.028(0.48, 8.10)
AT (%)	48.98 ± 20.15	44.38 ± 20.91	0.352(−5.19, 14.39)
MLDin (HU)	−854.00 ± 25.15	−846.82 ± 30.47	0.290 (−20.60, 6.24)
MLDex (HU)	−807.50 ± 45.96	−800.90 ± 41.94	0.529(−27.44,14.23)
TLVin (ml)	5981.02 ± 1132.63	5677.72 ± 1267.03	0.296(−271.74,878.34)
TLVex (ml)	4600.19 ± 1110.07	4391.24 ± 1176.42	0.448(−336.86,754.77)
post-BD
EI (%)	12.22± 8.87	7.81 ± 6.87	0.021(0.69, 8.14)
AT (%)	45.87 ± 20.27	37.27 ± 20.22	0.082 (−1.12, 18.31)
MLDin (HU)	−854.13 ± 24.31	−847.28 ± 23.08	0.229(−18.09,4.41)
MLDex (HU)	−797.34 ± 51.10	−779.77 ± 46.76	0.135(−40.78, 5.63)
TLVin (ml)	5908.01± 1060.56	5567.97 ± 1156.60	0.370(−290.26,770.34)
TLVex (ml)	4321.93 ± 1003.56	4024.32 ± 1249.93	0.280(−247.61,842.82)

The values are expressed as means ± SDs.

COPD = chronic obstructive pulmonary disease; ACOS = asthma COPD overlap syndrome; BD = bronchodilator; EI = emphysema index; AT = air trapping; MLDin = inspiratory mean lung density; MLDex = expiratory mean lung density; TLVin = inspiratory total lung volume; TLVex = expiratory total lung volume; CI = Confidence Interval.

Table 4. A comparison of the EI and AT distributions between the patients with COPD and ACOS.

	COPD			ACOS
	U	M	L	U	M	L	P value (95% CI)
Pre-BD
EI	6	10	16	18	13	8	0.015 (0.012, 0.017)
AT	9	11	12	18	14	7	0.134 (0.114, 0.127)
Post-BD
EI	7	9	16	17	13	9	0.045 (0.039, 0.047)
AT	10	10	12	18	12	9	0.328 (0.337, 0.356)

The values are expressed as frequency.

U = upper zone predominance; M = middle zone predominance; L = lower zone predominance;

COPD = chronic obstructive pulmonary disease; ACOS = asthma COPD overlap syndrome;

BD = bronchodilator; EI = emphysema index; AT = air trapping. CI = Confidence Interval.

Table 5. A comparison of the variations in pre- and post-BD whole-lung CT measurements between the patients with COPD and ACOS.

Variation	COPD	ACOS	P value (95% CI)
EI (%)	0.20 ± 2.47	0.31 ± 1.65	0.823(−0.19,0.88)
AT (%)	2.03 ± 7.29	7.11 ± 8.82	0.012(−9.00, -1.14)
MLDin (HU)	−0.13 ± 15.05	−0.46 ± 17.03	0.931(−7.36, 8.03)
MLDex (HU)	10.16 ± 18.32	21.13 ± 22.27	0.029(−20.77,-1.18)
TLVin (ml)	−73.02 ± 389.66	−9.75 ± 579.23	0.600(−302.60,176.07)
TLVex (ml)	−278.27 ± 494.45	−366.92 ±605.25	0.508(−176.96,354.26)

The values are expressed as means ± SDs.

BD = bronchodilator; COPD = chronic obstructive pulmonary disease; ACOS = asthma COPD overlap syndrome; EI = emphysema index; AT = air trapping; MLDin = inspiratory mean lung density;

MLDex = expiratory mean lung density; TLVin = inspiratory total lung volume; TLVex = expiratory total lung volum; CI = Confidence Interval.