Development and Validation of a Model for Predicting the Risk of Death in Patients with Acinetobacter baumannii Infection: A Retrospective Study

Figures & data

Table 1 Demographic and Clinical Characteristics of the Development and Validation Groups

Group	Development (n = 350) No. of Patients (%)	Validation (n = 272) No. of Patients (%)	P value
Sex			0.130
Male	231 (66.0)	195 (71.7)
Female	119 (34.0)	77 (28.3)
Age, year			0.195
>60	203 (58.0)	150 (55.1)
≦40	39 (11.1)	22 (8.1)
41–60	108 (30.9)	100 (36.8)
Infectious source			0.128
Respiratory tract	278 (79.4)	219 (80.5)
Pleural fluid and ascites	10 (2.9)	12 (4.4)
CSF	7 (2.0)	3 (1.1)
Urine	16 (4.6)	9 (3.3)
Blood	13 (3.7)	18 (6.6)
Skin and soft tissue	26 (7.4)	11 (4.0)
ICU admission history			0.608
Yes	200 (57.1)	161 (59.2)
No	150 (42.9)	111 (40.8)
CRAB			0.913
Yes	260 (74.3)	201 (73.9)
No	90 (25.7)	71 (26.1)
Hospitalization history			0.133
No	200 (57.1)	139 (51.1)
Yes	150 (42.9)	133 (48.9)
Anemia			0.327
No	120 (34.3)	83 (30.5)
Mild	141 (40.3)	122 (44.9)
Moderate	84 (24.0)	59 (21.7)
Severe	5 (1.4)	8 (2.9)
Hypoalbuminemia			0.138
No	218 (62.3)	185 (68.0)
Yes	132 (37.7)	87 (32.0)
CCI			0.273
<4	296 (84.6)	221 (81.2)
≥4	54 (15.4)	51 (18.8)
MV			0.080
Yes	176 (50.3)	156 (57.3)
No	174 (49.7)	116 (42.7)

Abbreviations: CCI, Charlson comorbidity index; CRAB, carbapenem-resistant Acinetobacter baumannii; CSF, cerebrospinal fluid; ICUs, intensive care units; MV, mechanical ventilation.

Table 2 Univariate and Multivariate Logistic Regression Models in the Development Group

	Univariate Analysis			Multivariate Analysis			Mortality (%)
	OR	95% CI	P	OR	95% CI	P
Sex
Male	1.0						65/231 (28.1)
Female	0.90	0.55–1.48	0.678				31/119 (26.1)
Age (year)
>60	1.0						58/203 (28.6)
≦40	1.56	0.77–3.19	0.220				15/39 (38.5)
41–60	0.68	0.39–1.18	0.165				23/108 (21.3)
Infectious source
Respiratory tract	1.0			1.0			78/278 (28.1)
Pleural fluid and ascites	1.10	0.28–4.36	0.893	2.13	0.45–10.04	0.341	3/10 (30.0)
CSF	3.42	0.75–15.63	0.113	5.49	1.07–28.14	0.041	4/7 (57.1)
Urine	0.00	0.00–Inf	0.979	0.00	0.00–Inf	0.988	0/16 (0)
Blood	5.77	1.73–19.28	0.004	4.64	1.26–17.06	0.021	9/13 (69.2)
Skin and soft tissue	0.21	0.05–0.93	0.039	0.31	0.07–1.44	0.136	2/26 (7.7)
ICU admission history
Yes	1.0			1.0			73/200 (36.5)
No	0.32	0.19–0.53	<0.001	1.41	0.56–3.55	0.465	23/150 (15.3)
CRAB
Yes	1.0			1.0			88/260 (33.8)
No	0.19	0.09–0.41	<0.001	0.36	0.15–0.90	0.029	8/90 (8.9)
Hospitalization history
No	1.0						54/200 (27)
Yes	1.05	0.65–1.69	0.836				42/150 (28)
Anemia
No	1.0						28/120 (23.3)
Mild	1.08	0.61–1.92	0.779				35/141 (24.8)
Moderate	1.83	0.99–3.38	0.055				30/84 (35.7)
Severe	4.93	0.78–30.99	0.089				3/5 (60)
Hypoalbuminemia
No	1.0			1.0			44/218 (20.2)
Yes	2.57	1.59–4.16	<0.001	2.04	1.19–3.48	0.009	52/132 (39.4)
CCI
<4	1.0			1.0			72/296 (24.3)
≫4	2.49	1.37–4.53	0.003	2.57	1.31–5.04	0.006	24/54 (44.4)
MV
Yes	1.0			1.0			71/176 (40.3)
No	0.25	0.15–0.42	<0.001	0.31	0.13–0.75	0.009	25/174 (14.4)

Abbreviations: CCI, Charlson comorbidity index; CI, confidence internal; CRAB, carbapenem-resistant Acinetobacter baumannii; CSF, cerebrospinal fluid; ICUs, intensive care units; MV, mechanical ventilation; OR, odds ratio.

Figure 1 Nomogram to predict the probability of risk of death from A. baumannii infection.

Abbreviations: CCI, Charlson comorbidity index; CRAB, carbapenem-resistant Acinetobacter baumannii; CSF, cerebrospinal fluid; MV, mechanical ventilation.

Figure 2 Example of prediction nomogram for the risk of death from A. baumannii infection.

Abbreviations: CCI, Charlson comorbidity index; CRAB, carbapenem-resistant Acinetobacter baumannii; CSF, cerebrospinal fluid; MV, mechanical ventilation.

Table 3 ROC Curve Analysis of the Development Group and Validation

Group	Development (n = 350)	Validation (n = 272)
Death	96	72
Survive	254	200
ROC	0.768	0.792
95% CI. low	0.715	0.733
95% CI. upp	0.821	0.851
Specificity	0.803	0.810
Sensitivity	0.583	0.639
Accuracy	0.743	0.765
Positive predictive value	0.528	0.548
Negative predictive value	0.836	0.862
a	56	46
b	50	38
c	40	26
d	204	162

Abbreviations: CI, confidence interval; ROC, receiver operating characteristic.

Figure 3 ROC curves for validating the discrimination of the nomogram. (A) Development group (B) Validation group (AUC = 0.768 vs 0.792).

Abbreviations: AUC, area under the curve; ROC, receiver operating characteristic.

Figure 4 DCA curves for validating the net income of the nomogram. (A) Development group (B) Validation group.

Abbreviation: DCA, decision curve analysis.

Figure 5 Calibration curves for validating the calibration of the nomogram. (A) Development group (B) Validation group.