Development and Validation of Nomogram to Predict Long-Term Prognosis of Critically Ill Patients with Acute Myocardial Infarction

Figures & data

Figure 1 Workflow of the inclusion and exclusion of the study subjects.

Abbreviation: ICU, intensive care unit.

Table 1 Characteristics of Critically Ill Patients with AMI in the Training and Validation Sets

	Cohort
Variable	Training (n = 841)	Validation (n = 361)	p value
Age (years)	68.2±13.7	67.4±14.3	0.477
Gender, n (%)
Female	303 (36.0)	127 (35.7)	0.922
Male	538 (64.0)	232 (64.3)
Ethnicity, n (%)
Caucasian	512 (60.9)	224 (62.0)	0.468
Black	30 (3.6)	8 (2.2)
Other	299 (35.6)	129 (35.7)
HR, n (%), beats/minute
≥70, <90	414 (49.2%)	182 (50.4%)	0.744
<70	182 (21.6%)	71 (19.7%)
≥90	245 (29.1%)	108 (29.9%)
RR, n (%), beats/minute
<20	599 (71.2%)	267 (74.0%)	0.332
≥20	242 (28.8%)	94 (26.0%)
SBP, n (%), mmHg
≥100, <120	441 (52.4%)	192 (53.2%)	0.968
<100	172 (20.5%)	72 (19.9%)
≥120	228 (27.1%)	97 (26.9%)
DBP, n (%), mmHg
≥55, <65	352 (41.9%)	158 (43.8%)	0.590
<55	265 (31.5%)	103 (28.5%)
≥65	224 (26.6%)	100 (27.7%)
SpO2, %	97.8 (96.5–98.7)	97.7 (96.3–98.6)	0.234
Temperature, n (%), °C
≥36, <37.5	677 (80.5%)	296 (82.0%)	0.791
<36	49 (5.8%)	18 (5.0%)
≥37.5	115 (13.7%)	47 (13.0%)
Weight, Kg	80.6±19.8	80.5±19.2	0.880
Scoring systems
SOFA	3.0 (1.0–6.0)	3.0 (1.0–5.0)	0.431
SAPS II	33.0 (25.0–44.0)	31.0 (23.0–43.0)	0.172
Comorbidities, n (%)
Cardiogenic shock	152 (18.1)	51 (14.1)	0.094
Cardiac arrest	63 (7.5)	29 (8.0)	0.746
CHF	70 (8.3)	25 (6.9)	0.410
Pulmonary circulation	5 (0.6)	2 (0.6)	1.000
Peripheral vascular disease	62 (7.4)	29 (8.0)	0.691
Valvular heart disease	25 (3.0)	7 (1.9)	0.308
Hypertension	65 (7.7)	14 (3.9)	0.014
Diabetes	223 (26.5)	68 (18.8)	0.004
Pneumonia	116 (13.8)	40 (11.1)	0.200
Respiratory failure	91 (10.8)	37 (10.2)	0.769
Liver diseases	12 (1.4)	3 (0.8)	0.394
Renal failure	87 (10.3)	23 (6.4)	0.029
Stroke	24 (2.9)	12 (3.3)	0.661
Depression	16 (1.9)	9 (2.5)	0.511
Hypothyroidism	19 (2.3)	25 (6.9)	0.285
Laboratory test
WBC (K/ul)	11.8 (9.5–15.0)	12.0 (9.5–14.7)	0.876
Platelet (K/ul)	214.0 (164.2–268.0)	218.0 (168.0–271.0)	0.288
Hemoglobin (g/dl)	11.6 (10.1–13.1)	11.8 (10.4–13.3)	0.753
Creatinine (mg/dl)	1.0 (0.8–1.3)	0.9 (0.7–1.2)	0.090
BUN (mg/dl)	19.0 (14.0–27.0)	18.0 (13.0–26.0)	0.148
Sodium (mmol/L)	139.0 (136.0–140.0)	138.0 (136.0–141.0)	0.711
Potassium (mmol/L)	4.1 (3.8–4.5)	4.1 (3.8–4.5)	0.974
Chloride (mmol/L)	105.0 (102.0–108.0)	105.0 (102.0–108.0)	0.307
Bicarbonate (mmol/L)	23.0 (20.0–25.0)	23.0 (21.0–25.0)	0.437
PT (second)	13.6 (12.8–14.8)	13.4 (12.7–14.6)	0.066
APTT (second)	36.6 (27.6–64.7)	35.2 (27.3–62.8)	0.297
cTnT, n (%)
< 1 ng/mL	235 (27.9)	101 (28.0)	0.554
≥1 ng/mL	187 (22.2)	90 (24.9)
Site of infarction, n (%)
Anterolateral wall	59 (7.0)	24 (6.6)	0.471
Anterior wall	249 (29.6)	117 (32.4)
Inferolateral wall	38 (4.5)	19 (5.3)
Inferoposterior wall	68 (8.1)	23 (6.4)
Inferior wall	233 (27.7)	110 (30.5)
Lateral wall	23 (2.7)	4 (1.1)
Other specified sites	27 (3.2)	9 (2.5)
Unspecified sites	144 (17.1)	55 (15.2)
Dialysis, n (%)	45 (5.4)	10 (2.8)	0.050
Vasopressor, n (%)	139 (16.5)	65 (18.0)	0.532
Ventilation, n (%)	229 (27.2)	97 (26.9)	0.898
PCI, n (%)	474 (56.4)	207 (57.3)	0.753
4-year overall survival	562 (66.8)	230 (63.7)	0.297

Abbreviations: AMI, acute myocardial infarction; HR, heart rate; RR, respiratory rate; SBP, systolic blood pressure; DBP, diastolic blood pressure; SpO2, percutaneous oxygen saturation; SOFA, stroke, and malignancy. Calculate the sequential organ failure assessment score; SAPS II, simplified acute physiology score II; PCI, percutaneous coronary intervention. CHF, congestive heart failure; WBC, white blood cell; BUN, blood urea nitrogen; PT, prothrombin time; APTT, activated partial thromboplastin time; cTnT, troponin T.

Table 2 Univariate Cox Regression Analysis of 4-Year Overall Survival in the Training Set

	Univariable Analysis
Variable	HR	95% CI	p value
Age (years)	1.05	1.04–1.06	< 0.0001
Gender, male	0.65	0.51–0.82	0.0004
HR (≥90 beats/minute)	1.64	1.27–2.13	0.0002
RR (≥20 beats/minute)	1.68	1.32–2.15	< 0.0001
SBP (<100mmHg)	1.79	1.35–2.38	< 0.0001
DBP (<55mmHg)	1.52	1.18–1.97	0.0014
Temperature (≥37.5°C)	1.66	1.22, 2.26	0.0013
Weight	0.98	0.98–0.99	< 0.0001
Dialysis	3.68	2.58–5.26	< 0.0001
Vasopressor	1.98	1.51–2.60	< 0.0001
Mechanical ventilation	2.28	2.23–3.58	< 0.0001
PCI	0.60	0.48–0.76	< 0.0001
Cardiogenic shock	2.61	2.02–3.38	< 0.0001
CHF	3.10	2.27–4.22	<0.0001
Valvular heart disease	1.89	1.10–3.23	0.0205
Pulmonary circulation	6.38	2.37–17.17	0.0002
Hypertension	1.82	1.27–2.60	0.0011
Pneumonia	2.88	2.20–3.77	< 0.0001
Respiratory failure	3.36	2.52–4.48	< 0.0001
Renal failure	2.18	1.60–2.97	< 0.0001
Stroke	2.48	1.45–4.24	0.0010
Anterior wall infarction	0.58	0.37–0.92	0.0192
WBC	1.04	1.02–1.06	0.0005
Hemoglobin	0.84	0.80–0.89	< 0.0001
Potassium	1.28	1.09–1.51	0.0033
Bicarbonate	0.91	0.89–0.94	< 0.0001
BUN	1.03	1.03–1.04	< 0.0001
Creatinine	1.31	1.24–1.39	< 0.0001
PT	1.05	1.02–1.07	0.0011
Lactate (≥2 mmol/L)	1.83	1.35–2.46	< 0.0001

Abbreviations: HR, heart rate; RR, respiratory rate; SBP, systolic blood pressure; DBP, diastolic blood pressure; PCI, percutaneous coronary intervention; CHF, congestive heart failure; WBC, white blood cell; BUN, blood urea nitrogen; PT, prothrombin time; HR, hazard ratio; CI, confidence interval.

Table 3 Multivariate Cox Regression Analysis of 4-Year Overall Survival in the Training Set

	Multivariate Analysis
Variable	HR	95% CI	p value
Age	1.05	1.04–1.06	< 0.0001
Respiratory rate	1.66	1.28–2.12	< 0.0001
Pneumonia	1.62	1.21–2.17	0.0010
Blood urea nitrogen	1.02	1.01–1.02	< 0.0001
Cardiogenic shock	1.99	1.52–2.60	< 0.0001
Dialysis	2.03	1.36–3.02	< 0.0001
Mechanical ventilation	1.90	1.45–2.48	< 0.0001
Hemoglobin	0.90	0.85–0.96	0.0010

Abbreviations: HR, hazard ratio; CI, confidence interval.

Figure 2 The nomogram for predicting the 4-year overall survival rate of patients with AMI. The nomogram included eight variables, including age, respiratory rate, blood urea nitrogen, cardiogenic shock, hemoglobin, pneumonia, and the use of dialysis and mechanical ventilation. In using the nomogram, a vertical line should be drawn upward from each variable to the “Points” line to obtain the score, and then the values are added to get the total score. Finally, a vertical line is drawn downward from the “Total Points” to obtain the 4-year overall survival of the patients with AMI.

Abbreviation: AMI, acute myocardial infarction.

Figure 3 The calibration curve of the nomogram for predicting the 4-year overall survival in the training (A) and the validation (B) sets. The dotted line represents the ideal curve where the predicted value is the same as the observed value. X-axis: survival as predicted by the nomogram; Y-axis: actual survival in the cohort.

Figure 4 The ROC curve of the nomogram, SOFA and SAPS II scores for predicting the 4-year overall survival in the training (A) and validation (B) vs X-axis: 1-specificity; Y-axis: sensitivity.

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