J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website https://www.jocmr.org

Original Article

Volume 14, Number 6, June 2022, pages 237-243

Association of Severe Obesity and Chronic Obstructive Pulmonary Disease With Pneumonia Following Non-Cardiac Surgery

Figure 1. Thirty-day cumulative incidence of postoperative pneumonia, unplanned reintubation, and requirement for an extended postoperative LOS among 450,405 patients undergoing general surgery. Patients with COPD were more likely to develop postoperative pneumonia (adjusted RR: 2.07; 95% CI: 1.84, 2.33), require unplanned reintubation (adjusted RR: 1.80; 95% CI: 1.56, 2.08) and extended LOS (adjusted RR:1.12; 95% CI: 1.08, 1.15), after adjusting for gender, current smoking status, American Society of Anesthesiologists (ASA) physical classification, diabetes, functional health status within 30 days of surgery, history of chronic heart failure within 30 days of surgery, hypertension, corticosteroid use for a chronic condition, surgical specialty, and year of surgery. LOS: length of stay; COPD: chronic obstructive pulmonary disease; RR: relative risk; CI: confidence interval.

**Table 1.** Baseline Characteristics of the Study Population (NSQIP 2014 - 2018)
Characteristics	Overall	COPD absent (n = 355,944)	COPD present (n = 9,329)
NSQIP: National Surgical Quality Improvement Program; COPD: chronic obstructive pulmonary disease; IQR: interquartile range; ASA: American Society of Anesthesiologists; CHF: chronic heart failure; ENT: ear, nose, and throat.
Study population	365,273	179,451 (50.4)	176,493 (49.6)	5,095 (54.6)	4,234 (45.4)
Age, median (IQR)	50 (38, 58)	52 (39, 59)	47 (37, 56)	59 (55, 62)	56 (51, 60)
Female sex	227,426 (62.3)	98,344 (54.8)	123,752 (70.1)	2,479 (48.7)	2,851 (67.3)
Smoker within 1 year of surgery	82,042 (22.5)	51,204 (28.5)	25,265 (14.3)	3,735 (73.3)	1,838 (43.4)
ASA ≥ 3	206,921 (56.7)	71,509 (39.9)	127,082 (72.1)	4,362 (85.7)	3,968 (93.9)
Diabetes	5,7027 (15.6)	12,987 (7.2)	41,619 (23.6)	634 (12.4)	1,787 (42.2)
Functional dependency	7,750 (2.1)	4,068 (2.3)	3,154 (1.8)	264 (5.2)	264 (6.3)
CHF 30 days before surgery	1,467 (0.4)	517 (0.3)	693 (0.4)	112 (2.2)	145 (3.4)
Hypertension requiring medication	129,615 (35.5)	40,655 (22.7)	83,033 (47.0)	2,733 (53.6)	3,194 (75.4)
Steroid use for chronic condition	18,696 (5.1)	12,562 (7.0)	5,445 (3.1)	404 (7.9)	285 (6.7)
Surgical specialty
General	235,823 (64.6)	105,331 (58.7)	126,095 (71.4)	2,130 (41.8)	2,267 (53.5)
Neurosurgery	31,343 (8.6)	19,564 (10.9)	10,837 (6.1)	619 (12.1)	323 (7.6)
Orthopedics	55,055 (15.1)	25,314 (14.1)	27,878 (15.8)	850 (16.7)	1,013 (23.9)
ENT	8,902 (2.4)	6,354 (3.5)	2,369 (1.3)	124 (2.4)	55 (1.3)
Urology	17,471 (4.8)	11,574 (6.4)	5,456 (3.1)	279 (5.5)	162 (3.8)
Vascular	16,679 (4.6)	11,314 (6.3)	3,858 (2.2)	1,093 (21.5)	414 (9.8)
Year of surgery
2014	66,085 (18.1)	32,691 (18.2)	31,613 (17.9)	988 (19.4)	793 (18.7)
2015	72,926 (20.0)	35,877 (20.0)	35,131 (19.9)	999 (19.6)	919 (21.7)
2016	78,235 (21.4)	37,962 (21.2)	38,384 (21.7)	1,022 (20.1)	867 (20.5)
2017	77,604 (21.2)	37,486 (20.9)	38,139 (21.6)	1,092 (21.4)	887 (20.9)
2018	70,423 (19.3)	35,435 (19.7)	33,226 (18.8)	994 (19.5)	768 (18.1)

Table 1. Baseline Characteristics of the Study Population (NSQIP 2014 - 2018)

Characteristics

Overall

COPD absent (n = 355,944)

COPD present (n = 9,329)

Normal weight

Severe obesity

Normal weight

Severe obesity

NSQIP: National Surgical Quality Improvement Program; COPD: chronic obstructive pulmonary disease; IQR: interquartile range; ASA: American Society of Anesthesiologists; CHF: chronic heart failure; ENT: ear, nose, and throat.

Study population

365,273

179,451 (50.4)

176,493 (49.6)

5,095 (54.6)

4,234 (45.4)

Age, median (IQR)

50 (38, 58)

52 (39, 59)

47 (37, 56)

59 (55, 62)

56 (51, 60)

Female sex

227,426 (62.3)

98,344 (54.8)

123,752 (70.1)

2,479 (48.7)

2,851 (67.3)

Smoker within 1 year of surgery

82,042 (22.5)

51,204 (28.5)

25,265 (14.3)

3,735 (73.3)

1,838 (43.4)

ASA ≥ 3

206,921 (56.7)

71,509 (39.9)

127,082 (72.1)

4,362 (85.7)

3,968 (93.9)

Diabetes

5,7027 (15.6)

12,987 (7.2)

41,619 (23.6)

634 (12.4)

1,787 (42.2)

Functional dependency

7,750 (2.1)

4,068 (2.3)

3,154 (1.8)

264 (5.2)

264 (6.3)

CHF 30 days before surgery

1,467 (0.4)

517 (0.3)

693 (0.4)

112 (2.2)

145 (3.4)

Hypertension requiring medication

129,615 (35.5)

40,655 (22.7)

83,033 (47.0)

2,733 (53.6)

3,194 (75.4)

Steroid use for chronic condition

18,696 (5.1)

12,562 (7.0)

5,445 (3.1)

404 (7.9)

285 (6.7)

Surgical specialty

General

235,823 (64.6)

105,331 (58.7)

126,095 (71.4)

2,130 (41.8)

2,267 (53.5)

Neurosurgery

31,343 (8.6)

19,564 (10.9)

10,837 (6.1)

619 (12.1)

323 (7.6)

Orthopedics

55,055 (15.1)

25,314 (14.1)

27,878 (15.8)

850 (16.7)

1,013 (23.9)

ENT

8,902 (2.4)

6,354 (3.5)

2,369 (1.3)

124 (2.4)

55 (1.3)

Urology

17,471 (4.8)

11,574 (6.4)

5,456 (3.1)

279 (5.5)

162 (3.8)

Vascular

16,679 (4.6)

11,314 (6.3)

3,858 (2.2)

1,093 (21.5)

414 (9.8)

Year of surgery

2014

66,085 (18.1)

32,691 (18.2)

31,613 (17.9)

988 (19.4)

793 (18.7)

2015

72,926 (20.0)

35,877 (20.0)

35,131 (19.9)

999 (19.6)

919 (21.7)

2016

78,235 (21.4)

37,962 (21.2)

38,384 (21.7)

1,022 (20.1)

867 (20.5)

2017

77,604 (21.2)

37,486 (20.9)

38,139 (21.6)

1,092 (21.4)

887 (20.9)

2018

70,423 (19.3)

35,435 (19.7)

33,226 (18.8)

994 (19.5)

768 (18.1)

**Table 2.** Associations of COPD, Stratified by Obesity Status, With Pneumonia, Unplanned Reintubation, and Extended LOS
Outcome	COPD	Obesity status	Number of children	Number of events	Risk, in % (95% CI)	Unadjusted analysis	Adjusted analysis
Models were adjusted for gender, current smoking status, American Society of Anesthesiologists (ASA) physical classification, diabetes, functional health status within 30 days of surgery, history of chronic heart failure within 30 days of surgery, hypertension, corticosteroid use for a chronic condition, surgical specialty, and year of surgery. COPD: chronic obstructive pulmonary disease; LOS: length of stay; CI: confidence interval.
Pneumonia	Absent	Normal weight	179,451	2,005	1.1	0.25 (0.22, 0.29)	< 0.001	0.53 (0.46, 0.61)	< 0.001
		Severe obesity	176,493	1,201	0.7	0.15 (0.13, 0.18)	< 0.001	0.30 (0.26, 0.35)	< 0.001
	Present	Normal weight	5,095	226	4.4	Reference	-	Reference	-
		Severe obesity	4,234	122	2.9	0.65 (0.52, 0.81)	< 0.001	0.76 (0.60, 0.95)	0.015
Unplanned reintubation	Absent	Normal weight	179,451	1,300	0.7	0.27 (0.22, 0.32)	< 0.001	0.60 (0.50, 0.72)	< 0.001
		Severe obesity	176,493	920	0.5	0.19 (0.16, 0.23)	< 0.001	0.39 (0.32, 0.47)	< 0.001
	Present	Normal weight	5,095	139	2.7	Reference	-	Reference	-
		Severe obesity	4,234	84	2.0	0.73 (0.55, 0.95)	0.021	0.79 (0.60, 1.05)	0.103
Extended LOS	Absent	Normal weight	179,451	63,807	35.6	0.74 (0.71, 0.77)	< 0.001	1.08 (1.03, 1.12)	< 0.001
		Severe obesity	176,493	32,946	18.7	0.39 (0.37, 0.41)	< 0.001	0.54 (0.51, 0.56)	< 0.001
	Present	Normal weight	5,095	2,441	47.9	Reference	-	Reference	-
		Severe obesity	4,234	1,591	37.6	0.78 (0.74, 0.84)	< 0.001	0.83 (0.78, 0.89)	< 0.001

Table 2. Associations of COPD, Stratified by Obesity Status, With Pneumonia, Unplanned Reintubation, and Extended LOS

Outcome

COPD

Obesity status

Number of children

Number of events

Risk, in % (95% CI)

Unadjusted analysis

Adjusted analysis

Risk ratio (95% CI)

P value

Risk ratio (95% CI)

P value

Models were adjusted for gender, current smoking status, American Society of Anesthesiologists (ASA) physical classification, diabetes, functional health status within 30 days of surgery, history of chronic heart failure within 30 days of surgery, hypertension, corticosteroid use for a chronic condition, surgical specialty, and year of surgery. COPD: chronic obstructive pulmonary disease; LOS: length of stay; CI: confidence interval.

Pneumonia

Absent

Normal weight

179,451

2,005

1.1

0.25 (0.22, 0.29)

< 0.001

0.53 (0.46, 0.61)

< 0.001

Severe obesity

176,493

1,201

0.7

0.15 (0.13, 0.18)

< 0.001

0.30 (0.26, 0.35)

< 0.001

Present

Normal weight

5,095

226

4.4

Reference

Severe obesity

4,234

122

2.9

0.65 (0.52, 0.81)

< 0.001

0.76 (0.60, 0.95)

0.015

Unplanned reintubation

Absent

Normal weight

179,451

1,300

0.7

0.27 (0.22, 0.32)

< 0.001

0.60 (0.50, 0.72)

< 0.001

Severe obesity

176,493

920

0.5

0.19 (0.16, 0.23)

< 0.001

0.39 (0.32, 0.47)

< 0.001

Present

Normal weight

5,095

139

2.7

Reference

Severe obesity

4,234

2.0

0.73 (0.55, 0.95)

0.021

0.79 (0.60, 1.05)

0.103

Extended LOS

Absent

Normal weight

179,451

63,807

35.6

0.74 (0.71, 0.77)

< 0.001

1.08 (1.03, 1.12)

< 0.001

Severe obesity

176,493

32,946

18.7

0.39 (0.37, 0.41)

< 0.001

0.54 (0.51, 0.56)

< 0.001

Present

Normal weight

5,095

2,441

47.9

Reference

Severe obesity

4,234

1,591

37.6

0.78 (0.74, 0.84)

< 0.001

0.83 (0.78, 0.89)

< 0.001