Asymptomatic Patients with Airflow Limitation are at Higher Risk of Postoperative Pulmonary Complications After Lung Surgeries: An Ambispective Cohort Study

Figures & data

Table 1 Baseline Characteristics of Study Population Prior to Propensity Score-Matching Analysis

	Total (n=535)	Normal Spirometry (n=409)	Newly Diagnosed AFL				P-value
			Total (n=126)	Mild (Group A, n=74)	Moderate to Severe (Group C, n=52)	P-value
Sex, male	310(57.9)	210(51.3)	100(79.4)	56(75.7)	44(84.6)	0.222	<0.001
Age, years	60(53–65)	59(52–64)	62(55.75–68)	60.45±9.02	62.33±9.93	0.271	<0.001
BMI, kg/m^2	25.08±3.39	25.19±3.34	24.74±3.56	25.23±3.89	24.05±2.91	0.055	0.193
Smoking status
Never	329(61.5)	282(68.9)	47(37.3)	32(43.2)	15(28.8)	0.202	<0.001
Ex-smoker	16(3.0)	10(2.4)	6(4.8)	4(5.4)	2(3.8)
Current-smoker	190(35.5)	117(28.6)	73(57.9)	38(51.4)	35(67.3)
BI	0(0–600)	0(0–375)	400(0–800)	200(0–725)	200(0–700)	0.021	<0.001
≥400	150(28.0)	88(21.5)	64(50.8)	29(39.2)	33(63.5)	0.007	<0.001
<400	385(72.0)	321(78.5)	62(49.2)	45(60.8)	19(36.5)
Comorbidity
DM	71(13.3)	52(12.7)	19(15.1)	10(13.5)	9(17.3)	0.558	0.494
Hypertension	124(23.2)	86(21.0)	38(30.2)	19(25.7)	19(36.5)	0.191	0.034
CHD	55(10.3)	41(10.0)	14(11.1)	8(10.8)	6(11.5)	0.898	0.725
ICVD	22(4.1)	18(4.4)	4(3.2)	3(4.1)	1(1.9)	0.502	0.544
ASA class
I, II	522(97.4)	400(97.8)	122(96.8)	73(98.6)	49(94.2)	0.305	0.516
III	13(2.4)	9(2.2)	4(3.2)	1(1.4)	3(5.8)
Perioperative pulmonary function
FEV1/FVC	75.77±8.09	79.19±5.11	64.67±5.66	67.11±2.62	61.20±6.92	<0.001	<0.001
FEV1%pred	100.08±19.05	104.99±16.84	84.13±16.99	94.60±12.80	69.22±9.36	<0.001	<0.001
Surgical procedure
Lobectomy	454(84.9)	346(84.6)	108(85.7)	68(91.9)	40(76.9)	0.023	0.406
Subsegmentectomy/ wedge	55(10.3)	44(10.8)	11(8.7)	2(2.7)	9(17.3)
Pneumonectomy	17(3.2)	14(3.4)	3(2.4)	1(1.4)	2(3.8)
Others	9(1.7)	5(1.2)	4(3.2)	3(4.1)	1(1.9)
Surgical method
VATS	445(83.2)	349(85.3)	96(76.2)	56(75.7)	40(76.9)	0.871	0.016
Open surgery	90(16.8)	60(14.7)	30(23.8)	18(24.3)	12(23.1)
Pathology
NSCLC
Adenocarcinoma	356(66.5)	273(66.7)	83(65.9)	49(66.2)	34(64.5)	0.529	0.317
Squamous	106(19.8)	75(18.3)	31(24.6)	20(27.0)	11(21.2)
Other NSCLC	9(1.7)	6(1.5)	3(2.4)	2(2.7)	1(1.9)
Metastatic disease	10(1.9)	8(2.0)	2(1.6)	1(1.4)	1(1.9)
Benign tumor	41(7.7)	36(8.8)	5(4.0)	2(2.7)	3(5.8)
Others	13(2.4)	11(2.7)	2(1.6)	0(0.0)	2(3.8)
Analgesia
PCA only	346(64.7)	265(64.8)	81(64.3)	44(59.5)	37(71.2)	0.382	0.930
Epidural +PCA	165(30.8)	125(30.6)	40(31.7)	27(36.5)	13(25.0)
Nerve block +PCA	24(4.5)	19(4.6)	5(4.0)	3(4.1)	2(3.8)

Notes: Data are expressed as mean ± SD or medians with an interquartile range (25–75).

Abbreviations: BMI, body mass index; BI, Brinkman Index; ICVD, ischemic cerebrovascular disease; DM, diabetes mellitus; CHD, coronary heart disease; ASA, American Society of Anesthesiologists; VATS, video-assisted thoracoscopic surgery; NSCLC, non-small cell lung cancer; PCA, patient-controlled analgesia.

Table 2 Baseline Characteristics of Study Patients After Propensity Score-Match Analysis

Total (n=242)	Normal Spirometry (n=121)	Newly Diagnosed AFL (n=121)	P-value
Sex, male	97(80.2)	95(78.5)	0.815
Age, years	62.07±8.10	60.93±9.42	0.276
BMI, kg/m^2	24.78±3.03	24.74±3.48	0.923
Smoking status
Never	55(45.5)	46(38.0)	0.425
Ex-smoker	6(5.0)	6(5.0)
Current-smoker	60(49.6)	69(57.0)
Brinkman Index	200(0–800)	400(0–800)	0.915
≥400	50(41.3)	58(47.9)	0.229
<400	71(58.7)	63(52.1)
Comorbidity
DM	23(19.0)	19(15.7)	0.627
Hypertension	30(24.8)	36(29.8)	0.451
CHD	21(17.4)	14(11.6)	0.281
ICVD	4(3.3)	4(3.3)	1.000
ASA class
I, II	119(98.3)	117(96.7)	0.687
III	2(1.7)	4(3.3)
Perioperative pulmonary function
FEV1/FVC	74.24±3.08	64.57±5.73	<0.001
FEV1%pred	99.62±26.50	83.73±17.17	<0.001
Surgical procedure
Lobectomy	104(86.0)	103(85.1)	0.549
Subsegmentectomy/wedge	10(8.3)	11(9.1)
Pneumonectomy	5(4.1)	3(2.5)
Others	2(1.7)	4(3.3)
Surgical method
VATS	96(79.3)	93(76.9)	0.749
Open surgery	25(20.7)	28(23.1)
Pathology
NSCLC
Adenocarcinoma	76(62.8)	80(66.1)	0.780
Squamous	31(25.6)	29(24.0)
Other NSCLC	3(2.5)	3(2.5)
Metastatic disease	1(0.8)	2(1.7)
Benign tumor	9(7.4)	5(4.1)
Others	1(0.8)	2(1.7)
Analgesia
PCA only	79(65.3)	78(64.5)	0.412
Epidural +PCA	41(33.9)	38(31.4)
Nerve block +PCA	1(0.8)	5(4.1)

Notes: Data are expressed as mean ± SD or medians with an interquartile range (25–75).

Abbreviations: BMI, body mass index; BI, Brinkman Index; ICVD, ischemic cerebrovascular disease; DM, diabetes mellitus; CHD, coronary heart disease; ASA, American Society of Anesthesiologists; VATS, video-assisted thoracoscopic surgery; NSCLC, non-small cell lung cancer; PCA, patient-controlled analgesia.

Figure 1 Flowchart of selection of the study population.

Abbreviation: AFL, airflow limitation.

Table 3 Multivariate Logistic Regression Analysis to Assess Predictors of PPCs

Variable	β	Wald	P-value	OR	95% CI
Age	0.040	8.627	0.003	1.041	1.013–1.069
Male	0.057	0.040	0.841	1.059	0.604–1.856
ASA III	−0.843	1.705	0.192	0.430	0.121–1.526
Newly diagnosed AFL	0.585	4.955	0.026	1.794	1.072–3.002
BI≥400	0.414	2.191	0.139	1.513	0.874–2.617
Lobectomy			0.803
Subsegmentectomy/wedge	0.220	0.361	0.548	1.246	0.607–2.557
Pneumectomy	0.492	0.710	0.400	1.635	0.521–5.131
Other surgical procedures	0.056	0.004	0.947	1.508	0.203–5.500

Abbreviations: ASA, American Society of Anesthesiologists; AFL, airflow limitation; BI, Brinkman Index; OR, odds ratio; CI, confidence index.

Table 4 Postoperative Outcomes Prior to Propensity Score-Match Analysis

	Total (n=535)	Normal Spirometry (n=409)	Newly Diagnosed AFL				P-value
			Total (n=126)	65%<FEV1/FVC < 70% (n=80)	FEV1/FVC ≤65% (n=46)	P-value
Mean LOS (days)	10(9–12)	10(9–11)	11(9–13.25)	10(9–13)	11(8–15)	0.177	<0.001
Overall in-hospital complications
PPCs (at least one)	95(17.8)	59(14.4)	36(28.6)	15(18.8)	21(45.7)	<0.001	<0.001
POP	82(15.3)	51(12.5)	31(24.6)	14(17.5)	17(37.0)	<0.001	<0.001
Respiratory failure	7(1.3)	3(0.7)	4(3.2)	0(0)	4(8.7)
Atelectasis	5(0.9)	4(1.0)	1(0.8)	1(1.3)	0(0)
Pulmonary aspiration	1(0.2)	1(0.2)	0(0)	0(0)	0(0)
Atrial fibrillation	3(0.6)	2(0.5)	1(0.8)	1(1.3)	0(0)	0.446	0.689
Acute myocardial infarction	2(0.4)	1(0.2)	1(0.8)	0(0)	1(2.2)	0.186	0.377
Aortic dissection	1(0.2)	1(0.2)	0(0)	0(0)	0(0)	1.000	0.578
Bronchopleural fistula	1(0.2)	0(0)	1(0.8)	0(0)	1(2.2)	0.186	0.072
Pulmonary embolism	1(0.2)	1(0.2)	0(0)	0(0)	0(0)	1.000	0.578
ICU admissions	39(7.3)	20(4.9)	19(15.1)	6(7.5)	13(28.3)	0.002	<0.001
Tracheal intubation	6(1.1)	4(1.0)	2(1.6)	0(0)	2(4.3)	0.002	0.001
90-day hospital readmissions secondary to PPCs	14(2.6)	4(0.7)	10(7.9)	2(2.5)	8(17.4)	0.005	<0.001
Current status (quality of life)
In good condition	370(69.2)	283(69.2)	87(69.0)	58(72.5)	29(63.0)	0.435	0.028
Out of condition	31(5.8)	18(4.4)	13(10.3)	7(8.8)	6(13.0)
Mortality
Total	74(13.8)	56(13.7)	18(14.3)	9(11.3)	9(19.6)	0.164	0.866
In-hospital mortality	4(0.7)	3(0.7)	1(0.8)	0(0)	1(2.2)		0.944
90-day mortality	9(1.7)	7(1.7)	2(1.6)	0(0)	2(4.3)		0.924
Causes of death
PPCs	4(0.7)	3(0.7)	1(0.8)	0(0)	1(2.2)	0.186	0.944
Surgery-related	2(0.4)	1(0.2)	1(0.8)	0(0)	1(2.2)		0.377
Cancer-related	59(11.0)	46(11.2)	13(10.3)	7(8.8)	6(13.0)		0.771
Others
Respiratory	3(0.6)	2(0.5)	1(0.8)	0(0)	1(2.2)		0.689
Cardiovascular	2(0.4)	1(0.2)	1(0.8)	1(1.3)	0(0)		0.377
Others	4(0.7)	3(0.7)	1(0.8)	1(1.3)	0(0)		0.944

Notes: Data are expressed as medians with an interquartile range (25–75).

Abbreviations: PPC, postoperative pulmonary complications; AFL, airflow limitation; LOS, the total length of stay in hospital after the date of surgery; POP, postoperative pneumonia.

Figure 2 Kaplan-Meier cumulative event curves of all-cause death before propensity score-matching.

Abbreviations: PSM, propensity score-matched analysis; AFL, airflow limitation.

Figure 3 Kaplan-Meier cumulative event curves of all-cause death after propensity score-matching.

Abbreviations: PSM, propensity score-matched analysis; AFL, airflow limitation.

Table 5 Postoperative Outcomes After Propensity Score-Match Analysis

	Normal Spirometry (n=121)	Newly Diagnosed AFL (n=121)	P-value
Mean LOS (days)	10(9–12)	11(9–13)	0.067
Overall in-hospital complications
PPCs	21(17.3)	35(28.9)	<0.001
ICU admissions	9(7.4)	18(14.8)	0.049
90-day hospital readmissions secondary to PPCs	2(1.7)	10(8.3)	0.021

Notes: Data are expressed as medians with an interquartile range (25–75).

Abbreviations: AFL, airflow limitation; LOS, the total length of stay in hospital after the date of surgery; PPC, postoperative pulmonary complications.