Significance of Stenotrophomonas maltophilia When Detected in Sputum of Ambulatory Patients with COPD

Figures & data

Table 1 Main Characteristics of Patients with COPD Included in the Study

	Presence of S. maltophilia	Controls	p-value
	n = 41	n = 352
Demographics
Age, year s	71.0 ± 8.2	68.9 ± 8.5	0.12
Male	28 (68)	195 (55)	0.11
Body mass index, kg/m2	27.2 ± 5.6	27.2 ± 6.3	0.99
Current smokers, %	8 (20)	84 (24)	0.53
Cumulative smoking exposure, pack-years	42.8 ± 18.5	41.3 ± 19.4	0.64
Disease severity
CAT score	24.0 ± 7.8	20.9 ± 7.4	0.01
AECOPD in the previous year	38 (93)	228 (65)	< 0.0001
Moderate exacerbations	2.5 ± 1.9	1.4 ± 1.6	< 0.0001
Severe exacerbations	0.9 ± 1.4	0.1 ± 0.4	< 0.0001
Number of hospital admission in the previous year	1.1 ± 1.7	0.2 ± 0.6	< 0.0001
GOLD A/B/C/D	0/8/1/32	17/161/12/162	0.001
Lung function
FEV1 post BD, L	0.98 ± 0.35	1.13 ± 0.48	0.06
FEV1 post BD, % predicted	39.3 ± 14.6	44.9 ± 16.7	0.10
GOLD stage 1/2/3/4	0/10/20/11	8/118/160/66	0.44
Therapy
LAMA	40 (98)	340 (97)	1.00
LABA	39 (95)	342 (97)	0.36
ICS	40 (98)	295 (84)	0.02
Triple therapy	38 (93)	284 (81)	0.08
Long term oral steroids	7 (17)	16 (5)	0.001
Macrolides	17 (42)	74 (21)	0.003
Antibiotics in the previous year	38 (95)	221 (63)	< 0.0001
Comorbidities
Charlson comorbidity index	6.1 ± 2.7	4.6 ± 2.1	< 0.0001
CAD and/or CHF	21 (51)	100 (28)	0.003
Hypertension	28 (68)	177 (50)	0.03
Diabetes	9 (22)	58 (17)	0.38
Cerebrovascular disease	7 (17)	19 (5)	0.004
Cancer in the last 5 years	13 (32)	47 (13)	0.002
Chronic kidney disease	1 (2.5)	4 (1.1)	0.53
Bronchiectasis	8 (20)	34 (10)	0.06

Note: Values in bold are significant (p < 0.05).

Abbreviations: BD, bronchodilator; CAD, coronary artery disease; CAT, COPD assessment test; CHF, chronic heart failure; ECOPD, exacerbation of COPD; FEV1, forced expiratory volume in the first second; GOLD, global initiative for chronic obstructive lung disease; ICS, inhaled corticosteroids; LABA, long-acting b2-agonist; LAMA, long-acting muscarinic antagonist.

Figure 1 Focused principal component analysis (FPCA) for the association between presence of S. maltophilia and several host factors. FPCA is a simple graphical display of correlation structures focusing on a particular dependent variable. The display reflects primarily the correlations between the dependent variable and all other variables (covariates) and secondarily, the correlations among the covariates. The dependent variable (the presence of S. maltophilia in the sputum) is at the center of the diagram, and the distance from this point to a covariate faithfully represents their pairwise Spearman correlation coefficient (using ranked values of continuous variables). Green covariates are positively correlated and yellow covariates negatively correlated with the dependent variable. Covariates (in bold) inside the red circle are significantly correlated with the dependent variable (with a p value < 0.05). The diagram also shows relationships between covariates as follows: correlated covariates are close (for positive correlations, allowing identification of clusters) or diametrically opposite vis‐a‐vis the origin (for negative correlations), whereas independent covariates make a right angle with the origin.

Figure 2 Kaplan–Meier survival curves over the first 36 months following sputum detection of S. maltophilia. Survival data was censored at 36 months. Mortality was adjusted for age, Charlson comorbidity index and FEV₁.