Factors Associated with Lethal Outcome in Patients with Severe Form of Influenza

Abstract

Introduction: Clinical manifestations of influenza range from relatively mild and self-limiting respiratory infections to severe clinical manifestations with significant morbidity and mortality. The awareness of predictive indicators for the lethal outcome of influenza is of particular significance in making timely and exact decision for adequate treatment. The aim of this study was to identify the factors in patients with a severe form of influenza, resulting in lethal outcome. Materials and methods:The investigation was a prospective group comparison conducted at the University Clinic for Infectious Diseases in Skopje, R. Macedonia in the period from January 01, 2012 to January 01, 2015. The study included adult patients with a severe form of influenza who were further categorized into a group of either survived patients or a group of deceased patients. Demographic, clinical and biochemical data were noted in all patients included in the study on admission. The variables of the univariate analysis that showed a significant difference in terms of the outcome were used for creating multivariate logistic and regression analysis of the outcome as dependent factors. The independent predictors for lethal outcome in severe cases of influenza were identified by using logistic regression. Results: The study included 87 patients with a severe form of clinical and laboratory confirmed influenza. The patients were divided in two groups: survived (n = 75) and deceased (n = 75). The overall mortality was 13.79%. Multivariate analysis conducted on admission to hospital identified cardiovascular comorbid diseases (p = 0.014), urea values higher than 8.3 U/L (p = 0.045) and SAPS score (p = 0.048) as independent predictors of the outcome in patients with severe form of influenza. Influenza patients with cardiovascular diseases had 2.024 times greater risk of death from influenza in comparison to the patients having influenza without history of such a disease (OR = 2.024 95% CI 1.842-17.337). Patients with serum urea values higher than 8.3 U/L had 1.89 times higher chance of death compared to patients with normal values (OR = 1.89 95% CI 1.091-11.432). The increase of the SAPS score in one point increased the chance of death in patients with influenza by 1.2% (OR = 1.12 95% CI 1.01-2.976). The ROC analysis indicated that cardiovascular diseases, increased urea values and SAPS score in combination act as a good prognostic model for the fatal outcome. The global authenticity of this predictive model to foresee lethal outcome amounts to 80%, sensitivity being 82%, and specificity 70%. Conclusion: Cardiovascular diseases, increased values of urea over 8.3 mmol/l and SAPS score are independent predictive indicators for lethal outcome in severe influenza. Early identification of the outcome predictors in patients with severe influenza will allow implementation of adequate medical treatment and will contribute to decreasing of mortality in patients with severe form of influenza.

Severe acute respiratory infections (SARI) from influenza in adult patients in Chile: the experience of a sentinel hospital

“…Several in-hospital mortality risk factors for severe influenza requiring hospital admission have been described. They include delayed medical attention; lung, kidney, liver, or cardiovascular disease; cancer chemotherapy; increased BUN or creatinine concentration; a high Simplified Acute Physiology Score (SAPS) or Sequential Organ Failure Assessment (SOFA) score; age > 65 or > 80 years; admission to the intensive care unit (ICU); development of acute respiratory distress syndrome (ARDS); bilateral lung involvement; mechanical ventilation requirement; superinfection; corticosteroid use; and pregnancy (28–34). The in-hospital risk factors found in this study cohort included admission to critical care beds; low Pa0 2 /Fi0 2 ratio; and high creatinine concentration.…”

External validation and update of a prognostic model to predict mortality in hospitalized adults with RSV: A retrospective Dutch cohort study

“…Consequently, we tested the incremental value of the model by adding objectively assessable predefined predictor variables (age, gender, urea, confusion, cardiovascular comorbidities, immunocompromised status, and the number of other comorbidities), based on the existing prognostic models for poor outcomes in patients with positive influenza virus. 26,27,31 We performed backward variable selection based on the Akaike information criterion and Occam's razor principle. Finally, we performed internal validation with optimism correction by bootstrap.…”

Prediction models for prognosis of influenza: a systematic review and critical appraisal

“…Twelve (35%) articles belonged to a multicenter study based on the prevalence of influenza [26, 34, 36, 40-43, 45-48, 51, 53]. However, only 5 (15%) were prospective studies [6,36,41,43,47,50,54].…”

“…However, some models have a high risk of bias, and the sample size is too small. In addition, this is because the selection of patients in the group is not representative and the model is overfitting [6,9,11,40]. Therefore, the performance estimates of some models are likely be misleading or optimistic [11,25,34,42].…”

“…Community influenza activity has long been a serious threat to global public health [1][2][3][4][5]. During seasonal epidemics, the number of severe cases registered worldwide is 3 to 5 million, and the number of lethal cases is 250,000-500,000 [6,7]. The prognosis of influenza patients ranges from asymptomatic infection to severe pneumonia and even acute respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome [1,[8][9][10].…”