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://jocmr.elmerjournals.com

Original Article

Volume 17, Number 11, November 2025, pages 608-617

Clinical Features and Prediction Model of Secondary Infection Risk in Adult Patients With Chronic Respiratory Diseases: A Case-Control Study

Figure 2. ROC curve of a predictive model for infections in patients with chronic respiratory diseases. BMI: body mass index; LY: lymphocyte count; ROC: receiver operating characteristic; TRPG: tricuspid regurgitation pressure gradient.

**Table 1.** The Diseases Type and Culture Result of 154 Patients With Chronic Respiratory Diseases
Characteristics	N (%)	Note
Chronic respiratory diseases
Interstitial pneumonia	55 (35.7)
Chronic obstructive pulmonary disease	68 (44.2)
Pulmonary fibrosis	15 (9.7)
Asthma	7 (4.5)
Bronchiectasis	5 (3.2)
Pulmonary cavity	5 (3.2)
Pulmonary tuberculosis	2 (1.3)
Culture results
Normal flora	100 (64.9)
Pseudomonas aeruginosa	20 (13.0)	Nonfermenters
Klebsiella pneumoniae	3 (1.9)	Enterobacteriaceae
Other Enterobacteriaceae	3 (1.9)	Enterobacteriaceae
Burkholderia cepacia and Acinetobacter baumannii	2 (1.3)	Nonfermenters
Burkholderia cepacia	1 (0.6)	Nonfermenters
Other nonfermenters	7 (4.5)	Nonfermenters
Staphylococcus aureus	1 (0.6)	Gram-positive bacteria
Aspergillus fumigatus	8 (5.2)	Filamentous fungi
Candidiasis	3 (1.9)	Yeast-like fungi
Acid-fast bacillus	5 (3.2)	Mycobacterium tuberculosis
Hemophilus	1 (0.6)	Hemophilus

Table 1. The Diseases Type and Culture Result of 154 Patients With Chronic Respiratory Diseases

Characteristics

N (%)

Note

Chronic respiratory diseases

Interstitial pneumonia

55 (35.7)

Chronic obstructive pulmonary disease

68 (44.2)

Pulmonary fibrosis

15 (9.7)

Asthma

7 (4.5)

Bronchiectasis

5 (3.2)

Pulmonary cavity

5 (3.2)

Pulmonary tuberculosis

2 (1.3)

Culture results

Normal flora

100 (64.9)

Pseudomonas aeruginosa

20 (13.0)

Nonfermenters

Klebsiella pneumoniae

3 (1.9)

Enterobacteriaceae

Other Enterobacteriaceae

3 (1.9)

Enterobacteriaceae

Burkholderia cepacia and Acinetobacter baumannii

2 (1.3)

Nonfermenters

Burkholderia cepacia

1 (0.6)

Nonfermenters

Other nonfermenters

7 (4.5)

Nonfermenters

Staphylococcus aureus

1 (0.6)

Gram-positive bacteria

Aspergillus fumigatus

8 (5.2)

Filamentous fungi

Candidiasis

3 (1.9)

Yeast-like fungi

Acid-fast bacillus

5 (3.2)

Mycobacterium tuberculosis

Hemophilus

1 (0.6)

Hemophilus

**Table 2.** The Common Clinical Characteristics of the Observation Group and the Control Group
Variables	Observation group (n = 54, 35.1%)	Control group (n = 100, 64.9%)	P value
ALB: albumin; BMI: body mass index; CRP: C-reactive protein; LY: lymphocyte count; NE: neutrophil count; PCT: procalcitonin; NT-proBNP: N-terminal pro-brain natriuretic peptide; LVEF: left ventricular ejection fraction (52-74%); TRPG: tricuspid regurgitation pressure gradient; WBC: white blood cell count.
Male (%)	42 (77.8)	64 (64.0)	0.078
Age (years, M (P₂₅, P₇₅))	72.0 (67.0, 80.0)	67.0 (58.0, 73.9)	< 0.001
Age of onset (years, M (P₂₅, P₇₅))	60.5 (50.0, 70.3)	57.0 (48.3, 69.0)	0.398
BMI (kg/m², M (P₂₅, P₇₅))	19.65 ± 3.87	23.13 ± 3.74	< 0.001
Hypertension (%)	22 (40.7)	36 (36.0)	0.562
Diabetes (%)	10 (18.5)	12 (12.0)	0.27
Smoking history (%)	15 (27.8)	22 (22.0)	0.423
The number of acute exacerbations ≥ 2/year (%)	18/35(51.4)	31/59 (52.5)	0.917
Clinical presentation (%)
Cough	44 (81.5)	83 (83.0)	0.813
Sputum	44 (81.5)	77 (77.0)	0.518
Chest tightness and asthma	38 (72.2)	61 (61.0)	0.164
Fever	15 (27.8)	20 (20.0)	0.272
Difficulty in breathing	12 (22.2)	12 (12.0)	0.095
Laboratory indicators (M (P₂₅, P₇₅))
WBC (× 10⁹/L)	9.0 (5.5, 13.6)	8.0 (5.9, 9.8)	0.275
LY (× 10⁹/L)	0.8 (0.4, 1.2)	1.4 (1.0, 1.8)	< 0.001
NE (× 10⁹/L)	7.3 (3.9, 11.9)	6.0 (4.0, 7.9)	0.084
NE (%)	85.1 (72.8, 90.9)	74.2 (64.6, 82.1)	< 0.001
CRP (mg/L)	18.9 (3.6, 93.1)	4.0 (1.9, 17.3)	0.003
PCT (ng/mL)	0.06 (0.03, 0.14)	0.03 (0.03, 0.08)	0.005
ALB (g/L)	33.0 (30.0, 36.4)	38.0 (33.8, 40.6)	< 0.001
NT-proBNP	385.5 (152.6, 136.3)	180.4 (55.4, 560.7)	0.051
LVEF (%)	62.0 (59.5, 64.5)	64.0 (60, 67.8)	0.156
TRPG (mm Hg)	30.7 (30.7, 36.0)	30.7 (25.0, 30.7)	0.001

Table 2. The Common Clinical Characteristics of the Observation Group and the Control Group

Variables

Observation group (n = 54, 35.1%)

Control group (n = 100, 64.9%)

P value

ALB: albumin; BMI: body mass index; CRP: C-reactive protein; LY: lymphocyte count; NE: neutrophil count; PCT: procalcitonin; NT-proBNP: N-terminal pro-brain natriuretic peptide; LVEF: left ventricular ejection fraction (52-74%); TRPG: tricuspid regurgitation pressure gradient; WBC: white blood cell count.

Male (%)

42 (77.8)

64 (64.0)

0.078

Age (years, M (P₂₅, P₇₅))

72.0 (67.0, 80.0)

67.0 (58.0, 73.9)

< 0.001

Age of onset (years, M (P₂₅, P₇₅))

60.5 (50.0, 70.3)

57.0 (48.3, 69.0)

0.398

BMI (kg/m², M (P₂₅, P₇₅))

19.65 ± 3.87

23.13 ± 3.74

< 0.001

Hypertension (%)

22 (40.7)

36 (36.0)

0.562

Diabetes (%)

10 (18.5)

12 (12.0)

0.27

Smoking history (%)

15 (27.8)

22 (22.0)

0.423

The number of acute exacerbations ≥ 2/year (%)

18/35(51.4)

31/59 (52.5)

0.917

Clinical presentation (%)

Cough

44 (81.5)

83 (83.0)

0.813

Sputum

44 (81.5)

77 (77.0)

0.518

Chest tightness and asthma

38 (72.2)

61 (61.0)

0.164

Fever

15 (27.8)

20 (20.0)

0.272

Difficulty in breathing

12 (22.2)

12 (12.0)

0.095

Laboratory indicators (M (P₂₅, P₇₅))

WBC (× 10⁹/L)

9.0 (5.5, 13.6)

8.0 (5.9, 9.8)

0.275

LY (× 10⁹/L)

0.8 (0.4, 1.2)

1.4 (1.0, 1.8)

< 0.001

NE (× 10⁹/L)

7.3 (3.9, 11.9)

6.0 (4.0, 7.9)

0.084

NE (%)

85.1 (72.8, 90.9)

74.2 (64.6, 82.1)

< 0.001

CRP (mg/L)

18.9 (3.6, 93.1)

4.0 (1.9, 17.3)

0.003

PCT (ng/mL)

0.06 (0.03, 0.14)

0.03 (0.03, 0.08)

0.005

ALB (g/L)

33.0 (30.0, 36.4)

38.0 (33.8, 40.6)

< 0.001

NT-proBNP

385.5 (152.6, 136.3)

180.4 (55.4, 560.7)

0.051

LVEF (%)

62.0 (59.5, 64.5)

64.0 (60, 67.8)

0.156

TRPG (mm Hg)

30.7 (30.7, 36.0)

30.7 (25.0, 30.7)

0.001

**Table 3.** Susceptibility Results of *Pseudomonas aeruginosa* to Common Antibiotics
Antibiotics	Resistant (%)	Intermediate (%)	Susceptible (%)
Piperacillin (n = 18)	21.1	15.8	63.2
Piperacillin tazobactam (n = 20)	15.0	10.0	75.0
Ceftazidime (n = 20)	10.0	10.0	80.0
Cefepime (n = 20)	5.0	15.0	80.0
Cefoperazone sulbactam (n = 20)	20.0	10.0	70.0
Imipenem (n = 20)	35.0	0.0	65.0
Meropenem (n = 20)	35.0	0.0	65.0
Gentamicin (n = 18)	0.00	44.4	55.6
Amikacin (n = 17)	0.0	10.0	90.0
Tobramycin (n = 18)	5.6	0.0	94.4
Ciprofloxacin (n = 20)	30.0	0.0	70.0
Levofloxacin (n = 18)	33.3	11.1	55.6

Table 3. Susceptibility Results of Pseudomonas aeruginosa to Common Antibiotics

Antibiotics

Resistant (%)

Intermediate (%)

Susceptible (%)

Piperacillin (n = 18)

21.1

15.8

63.2

Piperacillin tazobactam (n = 20)

15.0

10.0

75.0

Ceftazidime (n = 20)

10.0

80.0

Cefepime (n = 20)

5.0

15.0

80.0

Cefoperazone sulbactam (n = 20)

20.0

10.0

70.0

Imipenem (n = 20)

35.0

0.0

65.0

Meropenem (n = 20)

35.0

0.0

65.0

Gentamicin (n = 18)

0.00

44.4

55.6

Amikacin (n = 17)

0.0

10.0

90.0

Tobramycin (n = 18)

5.6

0.0

94.4

Ciprofloxacin (n = 20)

30.0

0.0

70.0

Levofloxacin (n = 18)

33.3

11.1

55.6

**Table 4.** Multivariate Logistic Regression Analysis of Chronic Respiratory Diseases With Infections
Variables	β	SE	Wald χ² value	OR value	P value	95% CI
ALB: albumin; BMI: body mass index; 95% CI: 95% confidence interval; CRP: C-reactive protein; LY: lymphocyte count; NE: neutrophil count; OR: odds ratio; TRPG: tricuspid regurgitation pressure gradient.
Age	0.02	0.03	0.236	1.015	0.627	0.956 - 1.078
BMI	-0.237	0.10	5.200	0.789	0.023	0.644 - 0.967
TRPG	0.109	0.05	5.015	1.116	0.025	1.014 - 1.228
NE%	-0.097	0.04	5.882	0.908	0.015	0.840 - 0.982
LY	-2.105	0.93	5.119	0.122	0.024	0.020 - 0.755
CRP	0.022	0.01	4.177	1.023	0.041	1.001 - 1.045
ALB	0.063	0.08	0.566	1.065	0.452	0.904 - 1.254

Table 4. Multivariate Logistic Regression Analysis of Chronic Respiratory Diseases With Infections

Variables

Wald χ² value

OR value

P value

95% CI

ALB: albumin; BMI: body mass index; 95% CI: 95% confidence interval; CRP: C-reactive protein; LY: lymphocyte count; NE: neutrophil count; OR: odds ratio; TRPG: tricuspid regurgitation pressure gradient.

Age

0.02

0.03

0.236

1.015

0.627

0.956 - 1.078

BMI

-0.237

0.10

5.200

0.789

0.023

0.644 - 0.967

TRPG

0.109

0.05

5.015

1.116

0.025

1.014 - 1.228

NE%

-0.097

0.04

5.882

0.908

0.015

0.840 - 0.982

-2.105

0.93

5.119

0.122

0.024

0.020 - 0.755

CRP

0.022

0.01

4.177

1.023

0.041

1.001 - 1.045

ALB

0.063

0.08

0.566

1.065

0.452

0.904 - 1.254

**Table 5.** The Predictive Value of BMI, LY, and TRPG for Infection in Patients With Chronic Respiratory Diseases
Variables	AUC	95% CI	P value	Sensitivity (%)	Specificity (%)
AUC: area under curve; BMI: body mass index; 95% CI: 95% confidence interval; LY: lymphocyte count; TRPG: tricuspid regurgitation pressure gradient.
BMI	0.734	0.625 - 0.844	0.000	66.0	76.9
LY	0.713	0.598 - 0.829	0.000	65.4	71.4
TPRG	0.672	0.547 - 0.797	0.007	34.6	90.1
Combination	0.788	0.689 - 0.887	0.000	65.4	81.3

Table 5. The Predictive Value of BMI, LY, and TRPG for Infection in Patients With Chronic Respiratory Diseases

Variables

AUC

95% CI

P value

Sensitivity (%)

Specificity (%)

AUC: area under curve; BMI: body mass index; 95% CI: 95% confidence interval; LY: lymphocyte count; TRPG: tricuspid regurgitation pressure gradient.

BMI

0.734

0.625 - 0.844

0.000

66.0

76.9

0.713

0.598 - 0.829

0.000

65.4

71.4

TPRG

0.672

0.547 - 0.797

0.007

34.6

90.1

Combination

0.788

0.689 - 0.887

0.000

65.4

81.3