Evaluation of Inflammatory Markers in COVID-19 Disease in Children

Objective: This study aims to determine the prognostic values of bio-markers obtained from complete blood count in the diagnosis of the coronavirus disease of 2019 (COVID-19) patients who came to the pedi-atric emergency department of Diyarbakir Pediatric Hospital. Material and Methods: A total of 190 child patients with COVID-19 with definite diagnosis and 41 healthy children as a control group were included in this study. The lymphocyte count, platelet count, mean platelet volume (MPV), plateletcrit (PCT), C-reactive protein (CRP), neu-trophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) obtained from the patients' complete blood count were evaluated.Results: A statistically significant difference was found between the pa-tient and control groups in the lymphocyte, platelet, NLR, PLR, SII, PCT, and CRP values (p= 0.001, p< 0.0001, p< 0.0001, p= 0.007, p= 0.001, p< 0.0001, and p= 0.002, respectively). A very good positive correla-tion was found between SII and NLR (r= 0.919, p< 0.0001). There was a good level of positive correlation between PLR and NLR and between SII and PLR (r= 0.746, p< 0.0001;r= 0.787, p< 0.0001, respectively), a moderate positive correlation was found between SII and CRP, between WBC and PLR, and between WBC and PLT (r= 0.432, p< 0.0001;r= 0.408, p< 0.0001;r= 0.538, p< 0.0001 respectively). The relationship between CRP and NLR and between PCT and SII was determined to be a weak positive correlation. The area under the curve for NLR, platelet, lym-phocyte was graded as moderate and for PCT very good. Cut-off points were found for the platelet count (<= 285.00;AUC= 0.740;95% CI= 0.644-0.836;p< 0.0001), lymphocyte count (<= 2.665;AUC= 0.727;95% CI= 0.633-0.821;p< 0.0001), NLR (>= 0.28;AUC= 0.707;95% CI= 0.611-0.803;p< 0.0001), and PCT (>= 0.83;AUC= 0.979;95% CI= 0.950-1.000;p< 0.0001).Conclusion: Platelet count, lymphocyte count, NLR and PCT can be used as inflammatory biomarkers that can predict prognosis in COVID-19 infec-tion in children.

Can systemic immune inflammation index at admission predict in-hospital mortality in chronic kidney disease patients with SARS-CoV-2 infection?

BACKGROUND AND AIM: Patients with chronic kidney disease (CKD) are susceptible to SARS-CoV-2 infection and more prone to develop severe disease. It is important to know predictors of poor outcomes to optimize the strategies of care. METHODS: 93 patients with CKD and 93 age-sex matched patients without CKD were included in the study. Data on demographic, clinical features, hematological indices and outcomes were noted and compared between the groups. Neutrophile to lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune inflammation index (SII) (platelet counts×neutrophil counts/lymphocyte counts) and lymphocyte-to-CRP ratio (LCR) were calculated on admission and the association of these markers with disease mortality in CKD patients was identified. RESULTS: CKD patients had higher risk of severe disease, and mortality compared to non-CKD patients (72% vs 50.5%, p=0.003, 36.6% vs 10.8%, p<0.001, respectively) and were more likely to have higher values of immuno-inflammatory indices (leukocyte count, neutrophil, NLR, SII and C-reactive protein, etc.) and lower level of lymphocyte and LCR. Also, higher levels of NLR, SII, PLR and lower level of LCR were seen in CKD patients who died compared to those recovered. In a receiver operating characteristic curve analysis, NLR, SII, PLR and LCR area under the curve for in-hospital mortality of CKD patients were 0.830, 0.811, 0.664 and 0.712, respectively. Among all parameters, NLR and SII gave us the best ability to distinguish patients with higher risk of death. Based on the cut-off value of 1180.5, the sensitivity and specificity of the SII for predicting in-hospital mortality were found to be 67.5% and 79.6%, respectively. The corresponding sensitivity and specificity of the NLR were 85.2% and 66.1%, respectively, at the cut-off value of 5.1. Forward stepwise logistic regression analysis showed that NLR (≥5.1), SII (≥1180.5) and LCR (≤9) were predictors for in-hospital mortality. CONCLUSION: We report for the first time that SII is able to distinguish COVID-19 infected CKD patients of worse survival and it is as powerful as NLR in this regard. As SII is easily quantified from blood sample data, it may assist for early identification and timely management of CKD patients with worse survival.

What is the role of prognostic indexes in COVID-19 patients with diabetes mellitus? Data of patients from Turkey.

Aim: We aimed to determine the prognostic performance of the Glasgow Prognostic Score (GPS), systemic immune-inflammation index and early warning score (the 'ANDC' system) in patients with diabetes mellitus who had COVID-19. Patients & methods: Patients were divided into two groups: with and without diabetes mellitus. Results: In the diabetic patient group, the rates of in-hospital mortality, intensive care unit hospitalization and corticosteroid treatment were higher compared with the nondiabetic patient group (p < 0.05). A GPS of 2 was useful for predicting in-hospital mortality in diabetic patients (p < 0.05). The ANDC score was significantly higher in diabetic patients (p < 0.05) and in diabetic patients with mortality and those who needed ICU hospitalization (p < 0.05). Conclusion: The presence of a GPS of 2 at the time of admission and a high ANDC value were associated with poor prognosis in diabetic COVID-19 patients.

Predictive Value of Systemic Immune-inflammation Index in Determining Mortality in COVID-19 Patients.

Aim: The aim of this study was to evaluate whether systemic immune-inflammation index (SII) could predict mortality in patients with novel coronavirus 2019 (COVID-19) disease. Methods: This two-center, retrospective study included a total of 191 patients with confirmed diagnosis of COVID-19 via nucleic acid test (NAT). The SII was calculated based on the complete blood parameters (neutrophil × platelet/lymphocyte) during hospitalization. The relationship between the SII and other inflammatory markers and mortality was investigated. Results: The mortality rate was 18.3%. The mean age was 54.32±17.95 years. The most common symptoms were fever (70.7%) and dry cough (61.3%), while 8 patients (4.2%) were asymptomatic. The most common comorbidities were hypertension (37.7%), diabetes (23.0%), chronic renal failure (14.7%), and heart failure (7.9%) which all significantly increased the mortality rate (p<0.001). There was a highly positive correlation between the SII and polymorphonuclear leukocyte (PNL), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) (r=0.754, p<0.001; r=0.812, p<0.001; r=0.841, p<0.001, respectively), while a moderate, positive correlation was found between the SII and C-reactive protein (CRP) (r=0.439, p<0.001). There was a significant correlation between the SII and mortality (U=1,357, p<0.001). The cut-off value of SII was 618.8 (area under the curve=0.751, p<0.001) with 80.0% sensitivity and 61.5% specificity. A cut-off value of >618.8 was associated with a 4.68-fold higher mortality. Conclusion: Similar to NLR and PLR, the SII is a proinflammatory marker of systemic inflammation and can be effectively used in independent predicting COVID-19 mortality.

Predictive Value of Systemic Immune-Inflammation index and Neutrophil-to-Lymphocyte Ratio in Patients with Severe COVID-19.

Objective: It was initially reported that a novel coronavirus (COVID-19) had been identified in Wuhan, China, in December 2019.To date, COVID-19 is still threatening all humanity and has affected the public healthcare system and the world economic situation. Neutrophil-to-lymphocyte ratio (NLR) has also been demonstrated that associated with severity of COVID-19, but little is known about systemic immune-inflammation index (SII) relation with COVID-19. Methods: One hundred and twenty-five patients with diagnosed COVID-19 including non-severe cases (n = 77) and severe cases (n = 48) were enrolled in this study. Each patient of clinical characteristic information, blood routine parameters, and the haemogram-derived ratios were collected, calculated, and retrospectively analyzed. Receiver operating characteristics (ROC) was performed to investigate whether these parameters could be used to the predictive value of patients with severe COVID-19. Results: White blood cell count (WBC), neutrophil count (NEU), red cell volume distribution width (RDW), NLR, Platelet to lymphocyte ratio (PLR), neutrophil-to-platelet ratio (NPR), and SII were significantly higher in the severe groups than in the non-severe group (p < 0.01).Conversely, the severe group had a markedly decreased lymphocyte count, basophil (Baso#) count, red blood cell count (RBC), Hemoglobin (HGB), hematocrit (HCT), and lymphocyte-to-monocyte ratio (LMR) (P < 0.01).ROC curve analysis showed the AUC, optimal cut-off value, sensitivity, specificity of NLR and SII to early predict severe-patients with COVID-19 were 0.867, 7.25, 70.83%, 92.21% and 0.860, 887.20, 81.25%, 81.82%, respectively. Conclusion The results suggest that the SII and NLR is a potential new diagnosed biomarker in severe-patients with COVID-19.

C-Reactive Protein-to-Albumin Ratio as a Prognostic Inflammatory Marker in COVID-19.

Objectives As a result of developed generalized inflammation, the main prognostic factor determining morbidity and mortality in coronavirus disease 2019 (COVID-19) patients is acute respiratory distress syndrome. The purpose of our study was to define (1) the laboratory tests that will contribute to the diagnosis and follow-up of COVID-19 patients, (2) the differences between the laboratory-confirmed (LC), unconfirmed (LUC), and control (C) groups, and (3) the variation between groups of acute-phase reactants and biomarkers that can be used as an indicator of disease severity and inflammation. Materials and Methods A total of 102 patients undergoing treatment with COVID-19 interim guidelines were evaluated. Reverse transcriptase-polymerase chain reaction (RT-PCR) test was positive in 56 (LC), classified as mild or severe, and negative in 46 (LUC) patients. In addition, 30 healthy subjects (C) with negative RT-PCR tests were also evaluated. All statistical analyses were performed with the SPSS 22.0 program and the p -values for significant findings were less than 0.05. Parametric/nonparametric distribution was determined by performing the Kolmogorov-Smirnov test for all groups. Student's t -test was used for variables with parametric distribution and the Mann-Whitney U-test for variables with the nonparametric distribution. A cut-off level for biomarkers was determined using the ROC (receiver operator characteristic) curve. Results In the LC group, platelet, platecrit, mean platelet volume, platelet diameter width, white blood cell, lymphocyte, eosinophil, neutrophil, immature granulocyte, immature lymphocyte, immature monocyte, large immune cell, and atypical lymphocyte counts among the complete blood count parameters of mature and immature cell counts showed a significant difference according to the C and LUC groups. C-reactive protein, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and C-reactive protein-to-albumin ratio (CAR) indices were significantly elevated in LC patients and were significantly higher in patients classified as severe compared to mild. When CAR optimal cutoff was determined as 0.475, area under the curve was 0.934, sensitivity was 90.91%, specificity was 86.21%, positive predictive value was 92.59%, and negative predictive value was 83.33%. The diagnostic accuracy for CAR was 89.29%. Conclusion The CAR index with the highest diagnostic value and the highest predictability could be the most useful biomarker in the diagnosis and evaluation of disease severity in COVID-19 patients.

COVID-19 is more dangerous for older people and its severity is increasing: a case-control study.

Coronavirus disease 2019 (COVID-19) triggers important changes in routine blood tests. In this retrospective case-control study, biochemical, hematological and inflammatory biomarkers between March 10, 2020, and November 30, 2020 from 3969 COVID-19 patients (3746 in the non-intensive care unit (non-ICU) group and 223 in the ICU group) were analyzed by dividing into three groups as spring, summer and autumn. In the non-ICU group, lymphocyte to monocyte ratio was lower in autumn than the other two seasons and neutrophil to lymphocyte ratio was higher in autumn than the other two seasons. Also, monocyte and platelet were higher in spring than autumn; and eosinophil, hematocrit, hemoglobin, lymphocyte, and red blood cells decreased from spring to autumn. In the non-ICU group, alanine aminotransferase and gamma-glutamyltransferase gradually increased from spring to autumn, while albumin, alkaline phosphatase, calcium, total bilirubin and total protein gradually decreased. Additionally, C-reactive protein was higher in autumn than the other seasons, erythrocyte sedimentation rate was higher in autumn than summer. The changes in routine blood biomarkers in COVID-19 varied from the emergence of the disease until now. Also, the timely changes of blood biomarkers were mostly more negative, indicating that the disease progresses severely. The study was approved by the Erzincan Binali Yildirim University Non-interventional Clinical Trials Ethic Committee (approval No. 86041) on June 21, 2021.

Can systemic immune inflammation index at admission predict in-hospital mortality in chronic kidney disease patients with SARS-CoV-2 infection?

Background and aim: Patients with chronic kidney disease (CKD) are susceptible to SARS-CoV-2 infection and more prone to develop severe disease. It is important to know predictors of poor outcomes to optimize the strategies of care. Methods: 93 patients with CKD and 93 age-sex matched patients without CKD were included in the study. Data on demographic, clinical features, hematological indices and outcomes were noted and compared between the groups. Neutrophile to lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune inflammation index (SII) (platelet counts × neutrophil counts/lymphocyte counts) and lymphocyte-to-CRP ratio (LCR) were calculated on admission and the association of these markers with disease mortality in CKD patients was identified. Results: CKD patients had higher risk of severe disease, and mortality compared to non-CKD patients (72% vs 50.5%, p = 0.003, 36.6% vs 10.8%, p < 0.001, respectively) and were more likely to have higher values of immuno-inflammatory indices (leukocyte count, neutrophil, NLR, SII and C-reactive protein, etc.) and lower level of lymphocyte and LCR. Also, higher levels of NLR, SII, PLR and lower level of LCR were seen in CKD patients who died compared to those recovered. In a receiver operating characteristic curve analysis, NLR, SII, PLR and LCR area under the curve for in-hospital mortality of CKD patients were 0.830, 0.811, 0.664 and 0.712, respectively. Among all parameters, NLR and SII gave us the best ability to distinguish patients with higher risk of death. Based on the cut-off value of 1180.5, the sensitivity and specificity of the SII for predicting in-hospital mortality were found to be 67.5% and 79.6%, respectively. The corresponding sensitivity and specificity of the NLR were 85.2% and 66.1%, respectively, at the cut-off value of 5.1. Forward stepwise logistic regression analysis showed that NLR (≥5.1), SII (≥1180.5) and LCR (≤9) were predictors for in-hospital mortality. Conclusion: We report for the first time that SII is able to distinguish COVID-19 infected CKD patients of worse survival and it is as powerful as NLR in this regard. As SII is easily quantified from blood sample data, it may assist for early identification and timely management of CKD patients with worse survival.

Antecedentes y objetivo: Los pacientes con enfermedad renal crónica (ERC) son susceptibles a la infección por SARS-CoV-2 y más propensos a desarrollar una enfermedad grave. Es importante conocer los predictores de los malos resultados para optimizar las estrategias de atención. Métodos: Se incluyeron en el estudio 93 pacientes con ERC y 93 pacientes sin ERC, emparejados por edad y sexo. Los datos sobre las características demográficas, clínicas, índices hematológicos y resultados, se anotaron y compararon entre los grupos. La proporción de neutrófilos a linfocitos (NLR), la proporción de plaquetas a linfocitos (PLR), el índice de inflamación inmunitaria sistémica (SII) (recuentos de plaquetas × recuentos de neutrófilos/recuentos de linfocitos) y la proporción de linfocitos a PCR (LCR) se calcularon en el momento de la admisión y se identificó la asociación de estos marcadores con la mortalidad por enfermedad en pacientes con ERC. Resultados: Los pacientes con ERC tuvieron un mayor riesgo de enfermedad grave y mortalidad en comparación con los pacientes sin ERC (72% vs 50,5%, p = 0,003, 36,6% vs 10,8%, p < 0,001, respectivamente) y tuvieron más probabilidades de tener valores más altos de índices inmuno inflamatorios (recuento de leucocitos, neutrófilos, NLR, SII y proteína C reactiva, etc.) y niveles más bajos de linfocitos y LCR. Además, se observaron niveles más altos de NLR, SII, PLR y un nivel más bajo de LCR en pacientes con ERC que murieron en comparación con los recuperados. En un análisis de la curva de características operativas del receptor, el área NLR, SII, PLR y LCR bajo la curva de mortalidad hospitalaria de pacientes con ERC fueron de 0,830, 0,811, 0,664 y 0,712, respectivamente. Entre todos los parámetros, NLR y SII se dió a conocer la mejor manera de distinguir a los pacientes con mayor riesgo de muerte. Con base en el valor de corte de 1180,5, se encontró que la sensibilidad y especificidad del SII, para predecir la mortalidad hospitalaria, fue del 67,5% y 79,6%, respectivamente. La sensibilidad y especificidad correspondientes del NLR fueron del 85,2% y 66,1%, respectivamente, en el valor de corte de 5,1.El análisis de regresión logística escalonada hacia adelante mostró que el NLR (≥5,1), SII (≥1180,5) y LCR (≤9) fueron predictores de mortalidad hospitalaria. Conclusión: Informamos, por primera vez, que el SII es capaz de distinguir pacientes con ERC infectados por COVID-19 de peor supervivencia y, en este sentido, es tan poderoso como el NLR. Como el SII se cuantifica fácilmente a partir de los datos de las muestras de sangre, puede ayudar a la identificación temprana y el manejo oportuno de los pacientes con ERC con peor supervivencia.

A composite risk model predicts disease progression in early stages of COVID-19: A propensity score-matched cohort study.

BACKGROUND: Recently, studies on COVID-19 have focused on the epidemiology of the disease and clinical characteristics of patients, as well as on the risk factors associated with mortality during hospitalization in critical COVID-19 cases. However, few research has been performed on the prediction of disease progression in particular group of patients in the early stages of COVID-19. METHODS: The study included 338 patients with COVID-19 treated at two hospitals in Wuhan, China, from December 2019 to March 2020. Predictors of the progression of COVID-19 from mild to severe stages were selected by the logistic regression analysis. RESULTS: COVID-19 progression to severe and critical stages was confirmed in 78 (23.1%) patients. The average value of the neutrophil-to-lymphocyte ratio (NLR) was higher in patients in the disease progression group than in the improvement group. Multivariable logistic regression analysis revealed that elevated NLR, LDH and IL-10 were independent predictors of disease progression. The optimal cut-off value of NLR was 3.75. The values of the area under the curve, reflecting the accuracy of predicting COVID-19 progression by NLR was 0.739 (95%CI: 0.605-0.804). The risk model based on NLR, LDH and IL-10 had the highest area under the ROC curve. CONCLUSIONS: The performed analysis demonstrates that high concentrations of NLR, LDH and IL-10 were independent risk factors for predicting disease progression in patients at the early stage of COVID-19. The risk model combined with NLR, LDH and IL-10 improved the accuracy of the prediction of disease progression in patients in the early stages of COVID-19.

Neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and systemic immune-inflammation index in patients with COVID-19-associated pneumonia.

INTRODUCTION: There are hematological parameters that correlate severity and predict mortality mainly in septic and inflammatory states. OBJECTIVE: To correlate the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic immune-inflammation index (SIII) with COVID-19 severity. METHOD: Descriptive, analytical, retrospective study of patients with COVID-19 pneumonia, in whom NLR, PLR and SIII were analyzed. RESULTS: One-hundred patients were included, 54 men and 46 women, with a mean age of 49.4 ± 19.3 years. NLR, PLR and SIII means were 10.7 ± 10.9, 290.1 ± 229.2, and 2.6 ± 3.4 x 109, respectively. In 54 %, pneumonia was mild, and in 46 %, severe. Regarding hospital outcomes, 75 % were discharged due to improvement and 25 % died. NLR, PLR and SIII means of the patients who died versus the patients who improved were 20.4 ± 16.9 versus 7.5 ± 4.9 (p = 0.001), 417.1 ± 379.7 versus 247.7 ± 127.4 (p = 0.038) and 4.8 ± 6.1 versus 1.9 ± 1.2 × 109 (p = 0.030), respectively. CONCLUSION: Hematological parameters can be used in patients with COVID-19-associated pneumonia as predictors of severity and prognosis. INTRODUCCIÓN: Existen índices hematológicos que correlacionan la severidad y predicen la mortalidad, principalmente en ­estados sépticos y de inflamación. OBJETIVO: Correlacionar los índices neutrófilo/linfocito (INL), plaqueta/linfocito (IPL) e inmunidad/inflamación sistémica (IIIS) con la severidad de COVID-19. MÉTODO: Estudio descriptivo, analítico y retrospectivo de pacientes con neumonía por COVID-19, en quienes se analizaron INL, IPL e IIIS. RESULTADOS: Se incluyeron 100 pacientes, 54 hombres y 46 mujeres, con una media de 49.4 ± 19.3 años. Las medias de INL, IPL e IIIS fueron 10.7 ± 10.9, 290.1 ± 229.2 y 2.6 ± 3.4 × 109, respectivamente. En 54 %, la neumonía fue leve y en 46 %, grave. En cuanto a los desenlaces hospitalarios, 75 % egresó por mejoría y 25 % falleció. Las medias de INL, IPL e IIIS de los pacientes que fallecieron versus las de los pacientes que mejoraron fueron 20.4 ± 16.9 versus 7.5 ± 4.9 (p = 0.001), 417.1 ± 379.7 versus 247.7 ± 127.4 (p = 0.038) y 4.8 ± 6.1 versus 1.9 ± 1.2 × 109 (p = 0.030), respectivamente. CONCLUSIÓN: Los índices hematológicos en pacientes con neumonía por COVID-19 pueden ser empleados como predictores de severidad y pronóstico.

Neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and systemic immune-inflammation index in patients with COVID-19-associated pneumonia / Índices neutrófilo/linfocito, plaqueta/linfocito e inmunidad/inflamación sistémica en pacientes con neumonía por COVID-19

Resumen Introducción: Existen índices hematológicos que correlacionan la severidad y predicen la mortalidad, principalmente en estados sépticos y de inflamación. Objetivo: Correlacionar los índices neutrófilo/linfocito (INL), plaqueta/linfocito (IPL) e inmunidad/inflamación sistémica (IIIS) con la severidad de COVID-19. Método: Estudio descriptivo, analítico y retrospectivo de pacientes con neumonía por COVID-19, en quienes se analizaron INL, IPL e IIIS. Resultados: Se incluyeron 100 pacientes, 54 hombres y 46 mujeres, con una media de 49.4 ± 19.3 años. Las medias de INL, IPL e IIIS fueron 10.7 ± 10.9, 290.1 ± 229.2 y 2.6 ± 3.4 × 109, respectivamente. En 54 %, la neumonía fue leve y en 46 %, grave. En cuanto a los desenlaces hospitalarios, 75 % egresó por mejoría y 25 % falleció. Las medias de INL, IPL e IIIS de los pacientes que fallecieron versus las de los pacientes que mejoraron fueron 20.4 ± 16.9 versus 7.5 ± 4.9 (p = 0.001), 417.1 ± 379.7 versus 247.7 ± 127.4 (p = 0.038) y 4.8 ± 6.1 versus 1.9 ± 1.2 × 109 (p = 0.030), respectivamente. Conclusión: Los índices hematológicos en pacientes con neumonía por COVID-19 pueden ser empleados como predictores de severidad y pronóstico.

Abstract Introduction: There are hematological parameters that correlate severity and predict mortality mainly in septic and inflammatory states. Objective: To correlate the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic immune-inflammation index (SII) with COVID-19 severity. Method: Descriptive, analytical, retrospective study of patients with COVID-19 pneumonia, in which NLR, PLR and SII were analyzed. Results: One-hundred patients were included, 54 men and 46 women, with a mean age of 49.4 ± 19.3 years. NLR, PLR and SII means were 10.7 ± 10.9, 290.1 ± 229.2, and 2.6 ± 3.4 × 109, respectively. In 54 %, pneumonia was mild, and in 46 %, severe. Regarding hospital outcomes, 75 % were discharged due to improvement and 25 % died. NLR, PLR and SII means of the patients who died versus the patients who improved were 20.4 ± 16.9 versus 7.5 ± 4.9 (p = 0.001), 417.1 ± 379.7 versus 247.7 ± 127.4 (p = 0.038) and 4.8 ± 6.1 versus 1.9 ± 1.2 × 109 (p = 0.030), respectively. Conclusion: Hematological parameters can be used in patients with COVID-19-associated pneumonia as predictors of severity and prognosis.