Risk factors for long-term mortality in patients admitted with severe infection

J. Francisco, I. Aragão, T. Cardoso

Severe infection is a main cause of mortality. We aim to describe risk factors for long-term mortality among inpatients with severe infection. Prospective cohort study in a 600-bed university hospital in Portugal including all patients with severe infection admitted into intensive care, medical, surgical, hematology and nephrology wards over one-year period. The outcome of interest was 5-year mortality following infection. Variables of patient background and infectious episode were studied in association with the main outcome through multiple logistic regression. There were 1013 patients included in the study. Hospital and 5-year mortality rates were 14 and 37%, respectively. Two different models were developed (with and without acute-illness severity scores) and factors independently associated with 5-year mortality were [adjusted odds ratio (95% confidence interval)]: age = 1.03 per year (1.02-1.04), cancer = 4.36 (1.65-11.53), no comorbidities = 0.4 (0.26-0.62), Karnovsky Index < 70 = 2.25 (1.48-3.40), SAPS (Simplified Acute Physiology Score) II = 1.05 per point (1.03-1.07), positive blood cultures = 1.57 (1.01-2.44) and infection by an ESKAPE pathogen (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeroginosa and Enterobacter species) = 1.61 (1.00- 2.60); and in the second model [without SAPS II and SOFA (Sequential Organ Failure Assessment) scores]: age = 1.04 per year (1.03-1.05), cancer = 5.93 (2.26-15.51), chronic haematologic disease = 2.37 (1.14-4.93), no comorbidities = 0.45 (0.29-0.69), Karnovsky Index< 70 = 2.32 (1.54- 3.50), septic shock [reference is infection without SIRS (Systemic Inflammatory Response Syndrome)] = 3.77 (1.80-7.89) and infection by an ESKAPE pathogen = 1.61 (1.00-2.60). Both models presented a good discrimination power with an AU-ROC curve (95% CI) of 0.81 (0.77-0.84) for model 1 and 0.80 (0.76-0.83) for model 2. If only patients that survived hospital admission are included in the model, variables retained are: age = 1.03 per year (1.02-1.05), cancer = 4.69 (1.71-12.83), chronic respiratory disease = 2.27 (1.09-4.69), diabetes mellitus = 1.65 (1.06-2.56), Karnovsky Index < 70 = 2.50 (1.63-3.83) and positive blood cultures = 1.66 (1.04-2.64) with an AU-ROC curve of 0.77 (0.73-0.81). Age, previous comorbidities, and functional status and infection by an ESKAPE pathogen were consistently associated with long-term prognosis. This information may help in the discussion of individual prognosis and clinical decision-making.