Cardiol Res

Cardiology Research, ISSN 1923-2829 print, 1923-2837 online, Open Access

Article copyright, the authors; Journal compilation copyright, Cardiol Res and Elmer Press Inc

Journal website https://www.cardiologyres.org

Original Article

Volume 11, Number 6, December 2020, pages 398-404

Cardiac Troponin-I and COVID-19: A Prognostic Tool for In-Hospital Mortality

**Table 1.** Baseline Characteristics and Mortality of Patients with COVID-19 Based on the Cardiac Troponin-I level (N = 257)
	Elevated troponin^b (n = 71)	Normal troponin^c (n = 186)	P value
*Statistically significant. ^a± SD. ^bElevated troponin: ≥ 0.012 ng/mL which falls above the 99th percentile in the blood test based on our facility’s laboratory data. ^cNormal troponin: < 0.012 ng/mL which falls below the 99th percentile in the blood test based on our facility’s laboratory data. COVID-19: coronavirus disease 2019; SD: standard deviation.
Baseline characteristics
Age, mean (SD^a), years	77(13)	58(16)	< 0.0001*
Sex, female (%)	35(49)	87(46)	0.7174
Body mass index, mean (SD^a), kg/m²	26(6.6)	30(7.9)	0.0002*
Race, Black (%)	13(18)	30(16)	0.2786
Ethnicity, Hispanic (%)	13(18)	45(24)	0.3034
Asthma (%)	4(5)	17(9)	0.3509
Chronic obstructive lung disease (%)	2(2)	5(2)	0.9621
Chronic kidney disease (%)	7(10)	3(1)	0.0024*
Atrial fibrillation/flutter (%)	14(20)	11(6)	0.0009*
Diabetes mellitus (%)	30(42)	42(22)	0.0019*
Hypertension (%)	56(79)	85(45)	< 0.0001*
Stroke/transient ischemic attack (%)	4(5)	6(3)	0.3786
Coronary artery disease (%)	21(30)	10(5)	< 0.0001*
Chronic heart failure (%)	11(15)	7(3)	0.0011*
Severe valvular disease (%)	2(2)	1(0.5)	0.1303
Coronary artery bypass graft surgery (%)	6(8)	1(0.5)	0.0020*
Peripheral vascular disease (%)	3(4)	5(2)	0.5327
Laboratory data at the time of admission
Blood urea nitrogen, mean (SD^a), mg/dL	40(31)	17(12)	< 0.0001*
Creatinine, mean (SD^a), mg/dL	1.7(1.3)	0.9(0.7)	< 0.0001*
Sodium, mean (SD^a), mEq/L	139(10)	136(3)	0.0235*
Random blood glucose level, mean (SD^a), mg/dL	181(131)	138(68)	0.0091*
Absolute lymphocyte count, mean (SD^a)	2(5)	1.8(4)	0.7991
Lactic acid, mean (SD^a), mmol/L	3(4)	1.2(0.5)	0.0046*
Total bilirubin, mean (SD^a), mg/dL	0.7(0.5)	0.5(0.3)	0.0055*
Albumin, mean (SD^a), mg/dL	3.5(0.5)	3.9(0.4)	< 0.0001*
In-hospital mortality or discharge to hospice, (%)	37(52)	19(10)	< 0.0001*

Table 1. Baseline Characteristics and Mortality of Patients with COVID-19 Based on the Cardiac Troponin-I level (N = 257)

Elevated troponin^b (n = 71)

Normal troponin^c (n = 186)

P value

*Statistically significant. ^a± SD. ^bElevated troponin: ≥ 0.012 ng/mL which falls above the 99th percentile in the blood test based on our facility’s laboratory data. ^cNormal troponin: < 0.012 ng/mL which falls below the 99th percentile in the blood test based on our facility’s laboratory data. COVID-19: coronavirus disease 2019; SD: standard deviation.

Baseline characteristics

Age, mean (SD^a), years

77(13)

58(16)

< 0.0001*

Sex, female (%)

35(49)

87(46)

0.7174

Body mass index, mean (SD^a), kg/m²

26(6.6)

30(7.9)

0.0002*

Race, Black (%)

13(18)

30(16)

0.2786

Ethnicity, Hispanic (%)

13(18)

45(24)

0.3034

Asthma (%)

4(5)

17(9)

0.3509

Chronic obstructive lung disease (%)

2(2)

5(2)

0.9621

Chronic kidney disease (%)

7(10)

3(1)

0.0024*

Atrial fibrillation/flutter (%)

14(20)

11(6)

0.0009*

Diabetes mellitus (%)

30(42)

42(22)

0.0019*

Hypertension (%)

56(79)

85(45)

< 0.0001*

Stroke/transient ischemic attack (%)

4(5)

6(3)

0.3786

Coronary artery disease (%)

21(30)

10(5)

< 0.0001*

Chronic heart failure (%)

11(15)

7(3)

0.0011*

Severe valvular disease (%)

2(2)

1(0.5)

0.1303

Coronary artery bypass graft surgery (%)

6(8)

1(0.5)

0.0020*

Peripheral vascular disease (%)

3(4)

5(2)

0.5327

Laboratory data at the time of admission

Blood urea nitrogen, mean (SD^a), mg/dL

40(31)

17(12)

< 0.0001*

Creatinine, mean (SD^a), mg/dL

1.7(1.3)

0.9(0.7)

< 0.0001*

Sodium, mean (SD^a), mEq/L

139(10)

136(3)

0.0235*

Random blood glucose level, mean (SD^a), mg/dL

181(131)

138(68)

0.0091*

Absolute lymphocyte count, mean (SD^a)

2(5)

1.8(4)

0.7991

Lactic acid, mean (SD^a), mmol/L

3(4)

1.2(0.5)

0.0046*

Total bilirubin, mean (SD^a), mg/dL

0.7(0.5)

0.5(0.3)

0.0055*

Albumin, mean (SD^a), mg/dL

3.5(0.5)

3.9(0.4)

< 0.0001*

In-hospital mortality or discharge to hospice, (%)

37(52)

19(10)

< 0.0001*

**Table 2.** Comparison of Clinical Characteristics Between Non-Survivors and Survivors Groups (N = 257)
	Non-survivors^b (n = 56)	Survivors^c (n = 201)	P value
*Statistically significant. ^a± SD. ^bNon-survivors: patients died during the index hospitalization or discharged to hospice. ^cSurvivors: Patients were discharged home alive. ^dElevated troponin: ≥ 0.012 ng/ml which falls above the 99th percentile in the blood test based on our facility’s laboratory data. SD: standard deviation; TIA: transient ischemic attack.
Characteristics
Age, mean (SD^a), years	75(14)	60(17)	< 0.0001*
Sex, female (%)	29(51)	93(46)	0.4839
Body mass index, mean (SD^a), kg/m²	28(7)	29(7)	0.2907
Race, Black (%)	6(10)	37(18)	0.3101
Ethnicity, Hispanic (%)	13(23)	45(22)	0.9144
Asthma (%)	3(5)	18(9)	0.3774
Chronic obstructive lung disease (%)	2(3)	5(2)	0.6658
Chronic kidney disease (%)	3(5)	7(3)	0.5281
Atrial fibrillation/flutter (%)	12(21)	13(6)	0.0009*
Diabetes mellitus (%)	21(37)	51(25)	0.0780
Hypertension (%)	40(71)	101(50)	0.0057
Stroke/TIA (%)	4(7)	6(3)	0.1581
Coronary artery disease (%)	9(16)	22(11)	0.3060
Chronic heart failure (%)	7(12)	11(5)	0.0707
Severe valvular disease (%)	2(3)	1(0.5)	0.0594
Coronary artery bypass graft surgery (%)	3(5)	4(2)	0.3477
Peripheral vascular disease (%)	1(1)	7(3)	0.5131
Laboratory data at the time of admission
Blood urea nitrogen, mean (SD^a), mg/dL	37(30)	19(17)	< 0.0001*
Creatinine, mean (SD^a), mg/dL	1.5(1.2)	1(0.9)	0.0097*
Random blood glucose level, mean (SD^a), mg/dL	194(128)	138(75)	0.0026*
Absolute lymphocyte count, mean (SD^a), × 10³ cells/µL	1.2(1.2)	2(5.5)	0.0499*
Sodium, mean (SD^a), mEq/L	138(9)	136(4)	0.0903
Lactic acid, mean (SD^a), mmol/L	3(4)	1(0.5)	0.0035*
Total bilirubin, mean (SD^a), mg/dL	0.7(0.5)	0.5(0.2)	0.0045*
Elevated troponin^d (%)	37 (66)	34(17)	< 0.0001*
Albumin, mean (SD^a), mg/dL	3.5(0.4)	3.8(0.4)	0.0004*

Table 2. Comparison of Clinical Characteristics Between Non-Survivors and Survivors Groups (N = 257)

Non-survivors^b (n = 56)

Survivors^c (n = 201)

P value

*Statistically significant. ^a± SD. ^bNon-survivors: patients died during the index hospitalization or discharged to hospice. ^cSurvivors: Patients were discharged home alive. ^dElevated troponin: ≥ 0.012 ng/ml which falls above the 99th percentile in the blood test based on our facility’s laboratory data. SD: standard deviation; TIA: transient ischemic attack.

Characteristics

Age, mean (SD^a), years

75(14)

60(17)

< 0.0001*

Sex, female (%)

29(51)

93(46)

0.4839

Body mass index, mean (SD^a), kg/m²

28(7)

29(7)

0.2907

Race, Black (%)

6(10)

37(18)

0.3101

Ethnicity, Hispanic (%)

13(23)

45(22)

0.9144

Asthma (%)

3(5)

18(9)

0.3774

Chronic obstructive lung disease (%)

2(3)

5(2)

0.6658

Chronic kidney disease (%)

3(5)

7(3)

0.5281

Atrial fibrillation/flutter (%)

12(21)

13(6)

0.0009*

Diabetes mellitus (%)

21(37)

51(25)

0.0780

Hypertension (%)

40(71)

101(50)

0.0057

Stroke/TIA (%)

4(7)

6(3)

0.1581

Coronary artery disease (%)

9(16)

22(11)

0.3060

Chronic heart failure (%)

7(12)

11(5)

0.0707

Severe valvular disease (%)

2(3)

1(0.5)

0.0594

Coronary artery bypass graft surgery (%)

3(5)

4(2)

0.3477

Peripheral vascular disease (%)

1(1)

7(3)

0.5131

Laboratory data at the time of admission

Blood urea nitrogen, mean (SD^a), mg/dL

37(30)

19(17)

< 0.0001*

Creatinine, mean (SD^a), mg/dL

1.5(1.2)

1(0.9)

0.0097*

Random blood glucose level, mean (SD^a), mg/dL

194(128)

138(75)

0.0026*

Absolute lymphocyte count, mean (SD^a), × 10³ cells/µL

1.2(1.2)

2(5.5)

0.0499*

Sodium, mean (SD^a), mEq/L

138(9)

136(4)

0.0903

Lactic acid, mean (SD^a), mmol/L

3(4)

1(0.5)

0.0035*

Total bilirubin, mean (SD^a), mg/dL

0.7(0.5)

0.5(0.2)

0.0045*

Elevated troponin^d (%)

37 (66)

34(17)

< 0.0001*

Albumin, mean (SD^a), mg/dL

3.5(0.4)

3.8(0.4)

0.0004*

**Table 3.** Cardiac Troponin-I Level as a Predictor of Mortality in Patients with COVID-19
Statistic	Value	95% confidence interval
*The prevalence of all-cause in-hospital mortality for the study population. Sensitivity, specificity, disease (mortality) prevalence, positive and negative predictive value as well as accuracy are expressed as percentages. Confidence intervals for sensitivity, specificity and accuracy are “exact” Clopper-Pearson confidence intervals. Confidence intervals for the likelihood ratios are calculated using the “Log method” as given on page 109 of Altman et al 2000 [7]. Confidence intervals for the predictive values are the standard logit confidence intervals given by Mercaldo et al 2007 [8]. COVID-19: coronavirus disease 2019.
Sensitivity	66%	52.1% - 78.1%
Specificity	83%	77.0% - 87.9%
Positive likelihood ratio	3.89	2.71 - 5.57
Negative likelihood ratio	0.41	0.28 - 0.59
Disease (mortality) prevalence	21.7% (mortality)*
Positive predictive value	51.9%	43% - 60.7%
Negative predictive value	89.7%	85.8% - 92.7%
Accuracy	79.3%	73.8% - 84.1%

Table 3. Cardiac Troponin-I Level as a Predictor of Mortality in Patients with COVID-19

Statistic

Value

95% confidence interval

*The prevalence of all-cause in-hospital mortality for the study population. Sensitivity, specificity, disease (mortality) prevalence, positive and negative predictive value as well as accuracy are expressed as percentages. Confidence intervals for sensitivity, specificity and accuracy are “exact” Clopper-Pearson confidence intervals. Confidence intervals for the likelihood ratios are calculated using the “Log method” as given on page 109 of Altman et al 2000 [7]. Confidence intervals for the predictive values are the standard logit confidence intervals given by Mercaldo et al 2007 [8]. COVID-19: coronavirus disease 2019.

Sensitivity

66%

52.1% - 78.1%

Specificity

83%

77.0% - 87.9%

Positive likelihood ratio

3.89

2.71 - 5.57

Negative likelihood ratio

0.41

0.28 - 0.59

Disease (mortality) prevalence

21.7% (mortality)*

Positive predictive value

51.9%

43% - 60.7%

Negative predictive value

89.7%

85.8% - 92.7%

Accuracy

79.3%

73.8% - 84.1%