Abstract

Introduction: There are very few studies on the TR value, which expresses the simultaneous increase in Troponin and Red Cell Distribution Width (RDW), which are markers of myocardial damage commonly seen in Covid-19 disease. This study aims to show the relationship of troponin, RDW and TR values with mortality and prognostic factors post-Covid-19.

Methods: 204 patients diagnosed with Covid-19 who were admitted to the adult tertiary Covid ICU between April,2021 and March,2022 were included in the study. Demographic data, comorbidities, treatments, length of stay in intensive care and hospital, and laboratory parameters were evaluated. According to our hospital's reference ranges, RDW value over 16% and troponin value over 15ng/L were defined as high value. Patients with both troponin value over 15ng/L and RDW value over 16% were considered to have high TR.

Results: In the study, when the values checked at the time of discharge/before discharge were examined, it was seen that the intubation rate was higher and the duration of mechanical ventilation was longer in patients with high troponin and TR levels. In patients with high RDW and TR values, platelet, hemoglobin and hematocrit values were lower before discharge/discharge compared to those with low RDW and TR values.

Conclusion: In our study, it was found that the intubation rate was higher and mechanical ventilation durations were longer in patients with elevated troponin and TR. We are of the opinion that early intubation practices applied in our clinic for patients with high TR and desaturation are reduced mortality.

Keywords: Covid-19, Intensive care, Post-covid-19, Red Cell Distribution Width, TR score, Troponin.

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Introduction :

Starting in the city of Wuhan, China in 2019 and rapidly spreading worldwide, the disease Covid-19 was declared a pandemic by the World Health Organization and is an extremely fatal viral illness1. As of May 24, 2023, there have been reported over 766 million cases of Covid-19 worldwide and more than 6.9 million deaths 2.

Acute myocardial injury, ischemia, and infarction risk can occur in relation to an increased inflammatory, prothrombotic, and procoagulant state following an acute infection (viral or bacterial) 3. Numerous studies have shown a strong association between high Red Cell Distribution Width (RDW) values and morbidity and mortality of coronary artery disease. Additionally, high RDW has been demonstrated to be an independent risk factor for both in-hospital and long-term mortality in patients with acute coronary syndrome (ACS) 4.

Myocardial injury is common in Covid-19 patients. The increase in cardiac troponin is among the prevalent prognostic factors indicating myocardial injury in Covid-19 patients. These increases in troponin can be due to chronic injury, acute non-ischemic injury, or acute myocardial infarction 5.

While there are studies showing the association between high RDW values and poor prognosis in Covid-19 , research exploring the relationship between troponin and RDW in predicting the prognosis of Covid patients is limited 6. During the pandemic period, the efficient use of resources in prognosis prediction is extremely important. Therefore, tests that are readily available and low-cost should be preferred. In our study, we aimed to demonstrate the relationship between troponin and RDW values and mortality in patients who have had Covid-19, and their association as prognostic factors.

Materials And Methods:

204 patients who were hospitalized with a diagnosis of Covid-19 between April 11, 2021, and March 16, 2022, in the adult tertiary care Covid ICU were included in the study. Ethical approval for this study (decision number: 716) was provided by the Medical Specialization Education Board of Health Sciences University Ankara Atatürk Chest Diseases and Thoracic Surgery Training and Research Hospital, Ankara, Turkey on 04 March 2021.

Patients requiring tertiary care ICU who were diagnosed with Covid-19 based on contact history, clinical and typical radiological findings, and a positive SARS-CoV-2 PCR test were included in the study. Patients who clinically suggested Covid but repeatedly received negative results from the SARS-CoV-2 PCR test were excluded from the study.

The age, gender, underlying diseases (presence of Diabetes Mellitus (DM), Hypertension (HT), Coronary Artery Disease (CAD), Congestive Heart Failure (CHF), previous Pulmonary Thromboembolism (PTE), previous Cerebrovascular Event (CVE), and Chronic Kidney Disease (CKD)), Charlson Comorbidity Index Score (CCIS), Acute Physiology and Chronic Health Evaluation Score-II (APACHE-II), Covid-19 vaccination history, tracheostomy and intubation status, need and duration for invasive/non-invasive mechanical ventilation (IMV/NIMV), need and duration for high-flow nasal oxygen (HFNO2), durations of stay in ICU and hospital, and 1-week and 1-month mortalities were recorded.

As laboratory parameters, complete blood count, D-dimer, Lactate Dehydrogenase (LDH), and troponin levels taken at the time of ICU admission and before discharge from the ICU or at the event of exitus were recorded. Since our hospital's reference value for RDW is between 11.8% and 16%, values above 16% were considered as high RDW. For troponin, the reference value is below 15ng/L, so values above 15ng/L were deemed as high troponin. Patients whose troponin values were above 15ng/L and whose RDW values were also above 16% were indicated as having high TR.

The effect of troponin, RDW, and TR elevation measured at the time of discharge/before exitus on prognosis and mortality was compared among the patients.

Statistical analysis and sample size

Data analyses were performed by using SPSS for Windows, version 22.0 (SPSS Inc., Chicago, IL, United States). Whether the distribution of continuous variables was normal or not was determined by the Kolmogorov Smirnov test. Levene test was used for the evaluation of homogeneity of variances. Unless specified otherwise, continuous data were described as mean ± SD and median (Q1 :first quartile – Q3 :third quartile). Categorical data were described as a number of cases (%). Statistical analysis differences in normally distributed variables between two independent groups were compared by Student’s t-test, Mann Whitney U test was applied for comparisons of the not normally distributed data. Categorical variables were compared using Pearson’s chi-square test or fisher’s exact test was accepted p-value <0.05 as a significant level on all statistical analysis.

Results:

Between April 11, 2021, and March 16, 2022, 111 male and 93 female patients were admitted to the adult tertiary care Covid ICU with a diagnosis of Covid-19. When patients were compared in terms of DM, HT, CAD, CHF, previous PTE, previous CVE, and CKD, it was found that the 1-month mortality was statistically significant in patients with a history of previous CVE. In those with detected 1-month mortality, compared to those without detected mortality, statistically the number of days on HFO2 and NIMV were lower, the number of intubations was lower, hospital stay was shorter, APACHE-II score was higher, admission lymphocyte value was lower, and admission leukocyte value was higher.

When comparing those with troponin values above 15ng/L to those with 15ng/L and below during the discharge/before exitus, it was observed that those with high troponin levels had statistically significant fewer days on NIMV, a higher rate of intubation and longer IMV duration, higher leukocyte values at admission and before discharge/exitus, and higher D-dimer and LDH values measured before discharge/exitus (Table-1).

Troponin ≤15 (n:57) Troponin >15(n:147) p value
Mean SD Median Q1 Q3 Mean SD Median Q1 Q3
Age 68.04 14.13 69.00 37.00 102.00 67.88 13.91 69.00 29.00 106.00 0.980*
HFO2 duration (day) 5.12 5.30 4.00 2.00 6.00 4.24 5.64 2.00 1.00 6.00 0.027*
NIMV duration (day) 5.12 5.30 4.00 2.00 6.00 4.18 5.64 2.00 1.00 5.50 0.018*
IMV Duration (day) 3.84 8.48 0 0 2.50 5.33 8.00 2.00 0 7.00 0.002*
LOS ICU 8.91 10.02 5.00 2.00 11.00 9.59 9.16 6.00 3.00 12.00 0.335*
LOS hospital 19.07 18.05 14.00 7.00 25.00 18.06 13.54 15.00 8.00 23.50 0.744*
CCIS 3.86 2.15 4.00 2.00 5.00 3.85 2.28 4.00 2.00 5.00 0.860*
APACHE-II 21.79 8.43 20.00 17.00 26.00 23.41 8.08 20.50 18.00 29.00 0.182*
Hos. leukocyte 11.75 5.93 10.60 8.21 13.65 14.05 7.06 13.25 9.36 17.29 0.009*
Hos.lymphocyte 0.93 1.05 0.61 0.38 1.14 0.86 1.12 0.63 0.45 0.94 0.834*
Hos. D-dimer 10.82 47.96 1.92 1.32 2.65 18.98 81.67 2.33 1.17 6.40 0.145*
Hos. LDH 556.85 270.59 534.00 382.00 705.00 623.97 775.31 498.00 356.00 697.00 0.655*
Hos. Hb 13.11 4.40 13.20 11.50 14.60 12.76 2.15 12.90 11.20 14.20 0.282*
Hos. Hct 39.62 7.18 40.60 35.40 44.40 39.29 5.89 39.00 35.10 43.10 0.793 β
Hos. Neutrophil 12.33 10.44 11.52 7.91 14.02 13.41 10.67 11.80 8.10 15.93 0.382*
Hos. Platelet 261.30 101.21 256.00 187.00 326.00 260.78 123.82 242.00 165.00 336.00 0.994 β
Hos. PDW 16.35 0.42 16.40 16.00 16.60 17.29 12.28 16.30 15.90 16.60 0.506*
Hos. PCT 0.25 0.09 0.25 0.18 0.31 1.63 11.98 0.26 0.18 0.33 0.531*
Hos. troponin 25.74 70.05 7.46 3.40 14.49 193.94 591.56 45.00 10.39 143.03 <0.001*
D/E Hb 11.80 2.64 11.70 10.60 13.30 11.66 2.33 11.70 10.10 12.90 0.782 β
D/E Htc 43.26 45.52 37.50 33.30 42.20 36.43 6.67 36.40 31.80 40.80 0.358*
D/E leukocyte 12.90 6.98 12.03 8.45 15.55 15.75 7.99 14.29 10.07 20.47 0.019*
D/E lymphocyte 1.29 2.38 0.74 0.53 1.12 2.25 5.23 0.75 0.43 1.51 0.651*
D/E Neutrophil 11.33 6.89 9.99 7.11 14.78 14.89 10.38 12.96 9.00 19.08 0.006*
D/E Platelet 240.74 132.47 230.00 152.00 307.00 204.27 126.08 189.00 98.00 277.00 0.064 β
D/E PDW 18.83 19.04 16.30 16.00 16.70 16.40 0.53 16.40 16.10 16.70 0.246*
D/E PCT 0.25 0.13 0.22 0.15 0.29 0.21 0.12 0.20 0.12 0.28 0.118*
D/E D-Dimer 4.45 7.25 1.97 0.94 3.50 8.91 11.80 3.93 1.65 11.87 <0.001*
D/E LDH 557.30 957.27 431.00 260.00 574.00 1325.63 2690.8 598.00 398.00 942.00 <0.001*
D/E RDW 15.14 4.58 14.30 13.40 16.20 15.86 2.86 15.10 13.90 17.10 0.055*
Continuous variables are expressed as the mean ± standard deviation (SD) and median(Q1 :first quartile – Q3 :third quartile). Continuous variables were compared with student test β or the mann whitney u test*. HFO2: High flow nasal oxygen, NIMV: Non invasive mechanical ventilation, IMV: Invasive mechanical ventilation, LOS: Length of stay, ICU:Intensive care unit, CCIS: Charlson Comorbidity Index, APACHE-II: Acute Physiology and Chronic Health Assessment Score-II, Hos: Hospitalization, LDH: Lactate Dehydrogenase, Hb: Hemoglobin, Htc: Hematocrit, PDW: Platelet distribution width, PCT: Procalcitonin, D/E: before discharge/exitus, RDW: Red Cell Distribution Width
Table 1. Comparison of the variables according to the troponin value measured before discharge/exitus

When comparing those with RDW values above 16% to those with 16% and below, it was observed that those with high RDW values had statistically significant lower levels of

hemoglobin, hematocrit, PDW values at admission and before discharge/exitus, and lower

platelet and PCT values measured before discharge/exitus compared to those with lower RDW values (Table-2).

RDW ≤16 (n:134) RDW >16(n:70) p value
Mean SD Median Q1 Q3 Mean SD Median Q1 Q3
Age 68.74 13.91 69.00 29.00 106.00 67.39 13.98 70.00 41.00 89.00 0.565*
HFO2 duration (day) 4.60 5.97 3.00 1.00 6.00 3.94 4.43 3.00 1.00 5.00 0.826*
NIMV duration (day) 4.54 5.97 2.50 1.00 6.00 3.96 4.42 3.00 1.00 5.00 0.973*
IMV Duration (day) 3.89 6.90 0 0 4.00 6.44 9.71 2.00 0 8.00 0.030*
LOS ICU 8.49 8.49 6.00 2.00 12.00 10.40 10.72 6.00 3.00 14.00 0.312*
LOS hospital 17.25 13.67 14.00 8.00 22.00 19.29 16.95 14.50 7.00 27.00 0.861*
CCIS 3.99 2.21 4.00 2.00 5.00 3.89 2.39 4.00 2.00 5.00 0.707*
APACHE-II 23.55 8.54 21.00 18.00 29.00 22.63 8.12 20.50 18.00 28.00 0.696*
Hos. leukocyte 13.63 7.09 12.50 8.70 16.73 12.96 6.62 12.01 8.47 15.30 0.454*
Hos.lymphocyte 0.85 0.85 0.62 0.41 0.94 0.94 1.44 0.66 0.40 1.05 0.799*
Hos. D Dimer 14.03 64.36 2.05 1.38 5.74 20.98 85.51 2.11 1.27 4.28 0.636*
Hos.LDH 632.62 777.02 523.00 382.00 684.00 549.81 356.67 468.00 352.00 708.00 0.429*
Hos. Hb 13.22 2.66 13.40 12.40 14.80 12.21 3.49 12.00 10.30 13.60 <0.001*
Hos. Hct 40.54 6.54 40.60 37.60 44.60 37.32 6.15 37.40 33.60 41.20 <0.001*
Hos. Neutrophil 13.73 12.53 11.01 7.45 15.59 11.63 4.59 11.80 8.06 14.09 0.952*
Hos. Platelet 268.81 121.51 256.50 176.00 344.00 240.04 110.28 240.00 147.00 309.00 0.106 β
Hos. PDW 17.47 12.68 16.40 16.10 16.70 16.12 0.49 16.10 15.70 16.40 <0.001*
Hos. PCT 0.57 3.44 0.26 0.18 0.34 2.37 16.14 0.24 0.17 0.32 0.181*
Hos. Troponin 187.74 611.31 22.40 5.80 137.00 71.31 139.51 21.80 6.80 69.90 0.360*
Hos. RDW 13.94 1.10 13.70 13.10 14.60 17.05 2.83 16.40 15.60 18.20 <0.001*
D/E Hb 12.26 2.55 12.35 11.00 13.90 10.75 2.07 10.90 9.10 12.10 <0.001 β
D/E Htc 40.58 30.15 37.90 34.20 42.50 34.50 6.26 34.80 29.90 38.60 <0.001*
D/E leukocyte 14.69 7.81 13.22 9.32 18.43 15.47 7.85 14.48 10.28 19.24 0.295*
D/E lymphocyte 2.12 5.30 0.73 0.41 1.24 1.78 3.00 0.76 0.53 1.81 0.083*
D/E Neutrophil 13.52 8.52 11.88 7.72 16.90 14.58 11.31 13.46 8.57 17.92 0.343*
D/E Platelet 234.50 132.40 226.00 140.00 296.00 172.59 108.51 162.00 89.00 240.00 0.001*
D/E PDW 17.56 12.41 16.50 16.20 16.80 16.18 0.51 16.20 15.90 16.50 <0.00 1*
D/E PCT 0.23 0.12 0.22 0.15 0.30 0.19 0.12 0.18 0.10 0.25 0.009 β
D/E D-Dimer 8.36 12.46 2.71 1.17 11.87 6.60 7.31 3.63 1.99 8.29 0.168*
D/E LDH 944.42 1918.29 502.00 334.00 776.00 1360.47 2914.53 534.00 383.00 943.00 0.180*
D/E Troponın 403.25 2326.88 34.60 11.50 133.10 1329.45 5776.11 49.10 17.00 352.20 0.070*
Continuous variables are expressed as the mean ± standard deviation (SD) and median(Q1 :first quartile – Q3 :third quartile). Continuous variables were compared with student test β or the ma*nn whitney u test*.HFO2: High flow nasal oxygen, NIMV: Non invasive mechanical ventilation, IMV: Invasive mechanical ventilation, LOS: Length of stay, ICU:Intensive care unit, CCIS: Charlson Comorbidity Index, APACHE-II: Acute Physiology and Chronic Health Assessment Score-II, Hos: Hospitalization, LDH: Lactate Dehydrogenase, Hb: Hemoglobin, Htc: Hematocrit, PDW: Platelet distribution width, PCT: Procalcitonin, RDW: Red Cell Distribution Width, D/E: before discharge/exitus
Table 2. Comparison of variables according to the RDW value measured before discharge/exitus

When comparing the high TR values (combined high troponin and RDW) measured at discharge/before exitus to the low TR values (low troponin and/or RDW), those with high TR values had a statistically significantly higher rate of intubation and longer MV duration. Those with low TR values had higher Hb, Htc, PDW values at admission and before discharge/exitus, and higher

PCT values before discharge/exitus. When compared to those with low TR values, those with high TR values had a higher RDW value at admission, lower platelet values before discharge/exitus, and statistically significantly higher D-dimer and LDH values measured before discharge/exitus. (Table 3).

TR LOW (N:134) TR HİGH (N:70) p value
Mean SD Median Q1 Q3 Mean SD Median Q1 Q3
Age 67.90 13.94 68.50 29.00 106.00 68.85 13.92 72.50 42.00 89.00 0.563*
HFO2 duration (day) 4.59 5.82 3.00 1.00 6.00 3.87 4.52 2.50 1.00 5.00 0.606*
NIMV duration (day) 4.53 5.81 3.00 1.00 6.00 3.88 4.51 2.50 1.00 5.00 0.729*
IMV Duration (day) 4.24 7.42 0 0 5.00 6.46 9.59 2.00 0 7.50 0.018*
LOS ICU 8.83 9.01 6.00 2.00 12.00 10.33 10.30 6.00 3.00 13.00 0.306*
LOS hospital 17.80 14.60 15.00 8.00 22.00 18.73 15.91 13.50 7.50 26.00 0.923*
CCIS 3.89 2.20 4.00 2.00 5.00 3.98 2.42 4.00 2.50 5.50 0.823*
APACHE-II 23.07 8.57 20.50 17.00 28.00 23.52 7.99 20.50 18.00 29.00 0.625*
Hos. leukocyte 13.40 7.06 12.16 8.35 16.65 13.48 6.68 12.36 9.35 16.27 0.767*
Hos.lymphocyte 0.86 0.85 0.62 0.41 1.10 0.95 1.59 0.67 0.51 1.05 0.649*
Hos. D-dimer 15.65 67.22 2.14 1.32 5.90 19.22 86.66 2.09 1.16 4.28 0.316*
Hos. LDH 634.27 743.80 530.00 382.00 721.00 521.54 354.60 431.00 348.00 635.00 0.135*
Hos. Hb 13.27 3.18 13.35 12.20 14.70 11.69 2.17 11.60 9.80 13.00 <0.001*
Hos. Hct 40.24 6.57 40.50 37.40 44.40 36.95 6.05 36.60 33.30 40.40 <0.001*
Hos. Neutrophil 13.51 11.94 11.01 7.91 15.59 11.54 4.44 11.80 8.06 13.96 0.948*
Hos. Platelet 268.34 119.47 257.00 176.00 344.00 231.84 110.99 230.00 146.00 292.00 0.056 β
Hos. PDW 17.35 11.98 16.40 16.10 16.70 16.10 0.49 16.10 15.70 16.40 <0.001*
Hos. PCT 0.53 3.25 0.26 0.18 0.34 3.07 18.58 0.23 0.16 0.30 0.153*
Hos. RDW 14.15 1.36 13.85 13.10 14.90 17.47 2.95 16.80 15.90 18.60 <0.001*
Hos.Troponın 168.42 579.51 15.80 5.59 113.00 89.63 156.49 32.61 7.30 96.70 0.477*
D/E Hb 12.09 2.50 12.15 10.80 13.60 10.63 2.11 10.90 8.50 12.10 <0.001*
D/E Htc 39.85 28.59 37.60 33.20 42.40 34.21 6.34 35.00 28.80 38.40 0.001*
D/E leukocyte 14.52 7.87 12.99 8.75 18.10 15.96 7.70 14.90 10.36 19.40 0.129*
D/E lymphocyte 2.06 5.04 0.74 0.43 1.27 1.86 3.34 0.75 0.49 1.68 0.452*
D/E Neutrophil 13.32 8.46 11.79 7.64 16.90 15.32 12.23 13.65 9.74 18.03 0.139*
D/E Platelet 230.93 131.45 206.00 136.00 292.00 161.51 104.44 157.00 82.00 221.00 <0.001*
D/E PDW 17.40 11.73 16.50 16.10 16.70 16.20 0.55 16.30 15.90 16.50 0.001*
D/E PCT 0.23 0.12 0.22 0.15 0.29 0.17 0.10 0.18 0.09 0.24 0.001*
D/E D-Dimer 7.66 11.67 2.70 1.18 9.33 7.53 8.02 3.84 2.30 10.80 0.02 3*
D/E LDH 888.98 1819.23 491.00 328.00 731.00 1650.68 3311.08 598.00 383.00 1138.00 0.013*
D/E Troponın 357.15 2189.93 28.25 8.10 127.60 1745.65 6582.39 107.25 39.00 451.40 <0.001*
D/E RDW 14.55 2.94 14.30 13.40 15.20 18.56 2.86 17.50 16.70 19.50 <0.001*
Continuous variables are expressed as the mean ± standard deviation (SD) and median(Q1 :first quartile – Q3 :third quartile). Continuous variables were compared with student test β or the mann whitney u test*.HFO2: High flow nasal oxygen, NIMV: Non invasive mechanical ventilation, IMV: Invasive mechanical ventilation, LOS: Length of stay, ICU:Intensive care unit, CCIS: Charlson Comorbidity Index, APACHE-II: Acute Physiology and Chronic Health Assessment Score-II, Hos: Hospitalization, LDH: Lactate Dehydrogenase, Hb: Hemoglobin, Htc: Hematocrit, PDW: Platelet distribution width, PCT: Procalcitonin, D/E: before discharge/exitus, RDW: Red Cell Distribution Width
Table 3. Comparison of variables according to the TR value measured before discharge/exitus

Discussion :

In this study, aimed at demonstrating the association of troponin and RDW values with mortality in Covid-19 patients and their relationship as prognostic factors, we analyzed the values taken at the time of discharge or just before exitus. Among those with elevated troponin levels, the intubation rate was higher and the duration of mechanical ventilation was longer compared to those with lower troponin levels. For patients with higher RDW values, platelet, hemoglobin, and hematocrit levels were lower at the time of discharge or just before exitus when compared to those with lower RDW values. In cases exhibiting both high troponin and RDW values (referred to as TR high), the intubation rate was more frequent and the mechanical ventilation duration was longer. Moreover, platelet, hemoglobin, and hematokrit levels were also found to be lower upon discharge or just before exitus compared to those with low TR values. Troponin and RDW values taken at admission were also found to be high during discharge.

In patients presenting to the intensive care unit with sepsis, elevated troponin levels have been associated with a longer duration of mechanical ventilation and have also been linked with a higher risk of developing septic shock 7. In a study examining severe Covid-19 patients, an increase in troponin value was found to be associated with higher needs for mechanical ventilation and higher mortality rates 8. In another study, troponin value was found to be an independent risk indicator for mortality and the need for invasive mechanical ventilation in patients hospitalized due to Covid-19 9.

While the troponin value can predict the need for mechanical ventilation and in-hospital mortality in Covid-19 patients, it cannot predict the duration of mechanical ventilation in these patients 10. In our study as well, we found that in patients with elevated troponin and TR values, the intubation rate was higher and the duration of mechanical ventilation was longer compared to those with lower troponin and TR values. No significant difference was observed between RDW and the duration of intubation and mechanical ventilation. The relationship between elevated TR values and the rate of intubation and the duration of

mechanical ventilation was thought to be a result of elevated troponin values. Even in critically ill patients admitted to intensive care without acute coronary syndrome or cardiac dysfunction, the risk of myocardial damage is quite high 11. There is often an imbalance between oxygen supply and demand in critically ill patients on mechanical ventilation. This condition causes dysfunction in many organs, including the myocardium. Since troponin is one of the earliest indicators of organ dysfunction, it can serve as a basis for initiating treatments aimed at improving general tissue oxygenation and perfusion early on 12.

RDW reflects erythrocyte morphology and is used in the differential diagnosis of anemias. It can also increase in conditions like systemic inflammation, nutritional disorders, ineffective erythropoiesis, and bone marrow dysfunction 13. Especially in septic shock patients accompanied by thrombocytopenia, a high RDW at presentation is commonly observed and is associated with mortality 14. In a meta-analysis conducted by Taneri and colleagues, it was demonstrated that hemoglobin and ferritin levels vary according to the severity of COVID-19 15. In our study as well, among COVID-19 patients, those who had higher RDW and TR values upon discharge or just before exitus exhibited lower levels of platelets, hemoglobin, and hematocrit. It should be kept in mind that in COVID-19 patients with elevated RDW, critical illness markers such as anemia and thrombocytopenia might also be present.

In deceased patients, while significant changes are observed in cardiac troponin levels, RDW values have been found to be one of the most effective predictive biomarkers for mortality risk in Covid-19 16. In a study examining 1198 patients, an increase in RDW value was shown to be associated with an increased risk of death for adult Covid-19 patients 17. Elevated RDW is a common finding in patients hospitalized due to Covid-19 and is present in almost half of the patients upon admission 18. In our study, an elevated RDW was observed in 34.3% of the Covid-19 patients monitored in intensive care. However, no statistically significant relationship was found between the values of troponin, RDW, and TR measured before discharge/death within one month and the mortality rate. We believe the reason for this discrepancy from the literature is the use of different reference ranges for elevated RDW and troponin values in the studies conducted.

The study had several limitations. Being a single-center, retrospective study, the number of patients was limited. Furthermore, since our study only looked at one-month mortality and post-discharge clinical status could not be determined, long-term outcomes are unknown. There is a need for larger, multi-center studies with longer follow-up durations to validate the findings.

Conclusion

Patients with elevated troponin and TR levels have a higher rate of intubation. Additionally, the duration of mechanical ventilation is also found to be longer in these patients.

However, no relationship was found between RDW and troponin values taken before death or at the time of discharge and one-month mortality. In our clinic, for patients with elevated TR levels and detected desaturation, we believe that the early intubation practice adopted by our clinic reduces mortality.

Acknowledgements: None

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