T wave peak-to-end interval in COPD

Figures & data

Table 1 Baseline demographic and respiratory test findings in the control and COPD groups

Findings	Control group		Case group		p-value
	Mean ± SD/n (%)	Med (Min–Max)	Mean ± SD/n (%)	Med (Min–Max)
Age, years	58.2±6.7	58 (44–65)	60.2±9.4	61 (34–82)	0.207a
Sex
Female	10 (24.39)		23 (17.16)		0.267b
Male	30 (73.2)		111 (82.8)
mMRC dyspnea score
Stage 0			11 (8.2)
Stage I			59 (44.0)
Stage II			26 (19.4)
Stage III			14 (10.4)
Stage IV			24 (17.9)
Combined assessment of COPD
Stage A			46 (34.3)
Stage B			23 (17.2)
Stage C			26 (19.4)
Stage D			39 (29.1)

Note:

a Student’s t-test,

b χ² test.

Abbreviations: mMRC, modified Medical Research Council; SD, standard deviation.

Table 2 Baseline demographic and biochemical findings in study population

Findings	n	Minimum	Maximum	Mean	SD
Age, years	134	34	82	60.2	9.42
Smoking	133	0	156	44.29	31.46
Saturation, %	134	75	99	96.60	2.97
CAT score	133	1	40	14.01	8.42
WBC, 10^3/µL	130	4.83	14.9	82.13	204.16
RBC, 10^6/µL	130	3.81	6.76	48.68	0.51
HB, g/dL	130	9.7	17.6	14.55	14.35
HCT, %	130	29.9	53.5	43.51	42.8
Sedimentation, mm/h	120	1	80	18.39	15.27
Glucose, mg/dL	95	50	260	100.24	28.04
Urea, mg/dL	118	16	66	33.41	9.05
Creatinine, mg/dL	118	0.57	1.25	0.87	0.16
Uric acid, mg/dL	85	2.4	8.9	5.18	11.15
Total protein, g/dL	92	5.6	8.6	7.45	0.47
Albumin, g/dL	94	3.2	5.2	4.32	0.34
Ca, mg/dL	93	8.4	10.5	9.45	0.46
Na, mEq/L	91	130	145	139.74	2.58
K, mmol/L	92	3.5	5.3	4.51	0.33
CRP, mg/L	130	0	67	5.95	7.63
FEV1 LT	134	0.44	3.14	15.21	0.59
FEV1 %	134	12.3	110	52.78	185.16
FVC LT	134	0.66	4.54	23.69	0.8
FVC %	134	19.3	121.7	65.6	194.25
FEV1/FVC, %	134	24.44	5,064	959	43.25
Heart rate	127	51	114	77.57	12.45
QRS duration, ms	127	66	170	92.56	13.79

Abbreviations: CAT, COPD Assessment Test; CRP, C-reactive protein; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; HB, hemoglobin; HCT, hematocrit; RBC, red blood cell; WBC, white blood cell.

Table 3 Tp–Te values compared between patients with COPD and controls

Tp–Te intervals	Control group		Case group		p-value
	Mean ± SD	Med (Min–Max)	Mean ± SD	Med (Min–Max)
Tp–Te V1	64.9±20.6	61 (40–123)	82.2±19.5	79 (43–154)	0.00a
Tp–Te V2	81.9±16.4	84 (52–119)	90.3±18.4	86 (49–145)	0.017a
Tp–Te V3	79.3±15.6	78 (51–109)	90.6±15.8	90 (32–141)	0.00a
Tp–Te V4	70.3±12.4	71 (43–98)	89.7±16.9	89 (30–129)	0.00a
Tp–Te V5	75.3±11.7	75 (47–102)	86.9±17.7	85 (54–185)	0.00a
Tp–Te V6	68.6±12.3	69 (40–89)	84.6±15.9	85 (42–128)	0.00a

Note:

a Mann–Whitney U-test.

Abbreviations: SD, standard deviation; Tp–Te, interval between the peak and end of the T wave.

Table 4 AUC values of Tp–Te compared between control and COPD groups

Tp–Te intervals	AUC	95% CI	p-value
Tp–Te V1	0.765	0.657–0.873	<0.001
Tp–Te V2	0.631	0.535–0.727	0.013
Tp–Te V3	0.708	0.611–0.805	<0.001
Tp–Te V4	0.831	0.765–0.896	<0.001
Tp–Te V5	0.716	0.629–0.803	<0.001
Tp–Te V6	0.786	0.712–0.860	<0.001
ROC curve

Abbreviations: AUC, area under the curve; CI, confidence interval; ROC, receiver operating characteristic; Tp–Te, interval between the peak and end of the T wave.

Figure 1 ROC curve for Tp–Te V4.

Abbreviations: ROC, receiver operating characteristic; Tp–Te, interval between the peak and end of the T wave.

Table 5 Tp–Te V4 values compared between in COPD stages

COPD stages	Tp–Te V4		Tp–Te V4 >80		p-value
	Mean ± SD	Median	N	%
Combined assessment of COPD					0.005a
Stage A	85.0±17.6	85.0	30	65.2
Stage B	86.0±16.7	84.5	16	69.6
Stage C	91.8±16.6	92.5	18	69.2
Stage D	96.6±14.0	96.5	36	92.3

Note:

a Kruskal–Wallis (Mann–Whitney U-test).

Abbreviations: SD, standard deviation; Tp–Te, interval between the peak and end of the T wave.

Figure 2 Tp–Te V4 measurements in COPD patients according to stages.

Abbreviation: Tp–Te, interval between the peak and end of the T wave.