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Early predictors of mortality in pneumococcal bacteraemia
I Balakrishnan1, P Crook, R Morris
1Department of Medical Microbiology, Royal Free and University College Medical School, University College London, UK.
Insights
Pneumococcal bacteraemia has a high mortality rate. Early identification of high-risk patients using clinical factors like age and acidosis can improve outcomes.
Area of Science:
- Infectious Diseases
- Critical Care Medicine
- Epidemiology
Background:
- Pneumococcal bacteraemia has a significant mortality rate, with many deaths occurring within 48 hours of admission.
- Early identification of critically ill patients is crucial for timely and effective management to influence outcomes.
Purpose of the Study:
- To develop an evidence-based assessment for clinicians to rapidly identify patients with pneumococcal bacteraemia at high risk of mortality.
- To identify independent predictors of case fatality in pneumococcal bacteraemia to guide early management strategies.
Main Methods:
- Retrospective data collection from medical records, including history, physical examination, radiological, and laboratory findings.
- Statistical analysis using Pearson's Chi-squared test and stepwise logistic regression to identify significant predictors of case fatality (P < 0.05).
Main Results:
- Overall case fatality was 21%. Independent predictors of higher case fatality included older age, acidosis, and elevated serum alanine aminotransferase (ALT).
- Serotype 14 was the most common and associated with higher fatality. Colder weather correlated with increased incidence and fatality.
- Patients receiving intensive therapy (ITU) had a 44% case fatality rate, and less than 50% of deceased patients received ITU management.
Conclusions:
- Despite advances in antibiotics and vaccines, pneumococcal bacteraemia mortality remains high.
- Clinical parameters identified can facilitate early risk stratification, potentially improving patient outcomes.
- Vaccination strategies, particularly for the elderly, may reduce incidence and mortality; further research on intensive therapy's impact is needed.
Objectives:
Pneumococcal bacteraemia carries a mortality of about 20%. Approximately 50% of deaths from pneumococcal bacteraemia occur within the first 48 h of admission. In order to influence outcome, critically ill patients should be identified at the time of presentation. This study enables the clinician to rapidly make an evidence-based assessment of a patient's prognosis, allowing the identification of patients who should be placed in a high-risk category at an early stage, when appropriate management is most likely to be effective.
Methods:
Data were collected from the medical record of history, physical examination, radiological examination and laboratory investigations done on initial presentation using a standardized proforma. The data were first examined by Pearson's Chi-squared test, with Yates' correction if needed. Variables found to be significantly associated with case fatality ( P < 0.05) by these methods were examined by stepwise logistic regression analysis in order to identify those factors which were independent predictors of case fatality.
Results:
The overall case fatality was 21%. Older age, apyrexia, tachypnoea, bilateral consolidation, hypoalbuminaemia, elevated aminotransferases, renal impairment, acidosis and leucopaenia were significantly associated with higher case fatality. Older age, acidosis and elevated serum alanine aminotransferase (ALT) were independent predictors of case fatality. Fifty-five percent of isolates belonged to serotypes 4, 6B, 9V, 14, 19F and 23F, to which good antibody levels have been documented in both young and elderly patients post-vaccination. Serotype 14 was most common, and was significantly associated with higher case fatality. Colder weather was associated with a higher incidence of both infection and case fatality. The case fatality amongst patients receiving ITU management was 44%. Less than 50% of patients who died received ITU management.
Conclusions:
Despite the increased availability of new antibiotics and vaccines, the mortality of patients with pneumococcal bacteraemia remains unchanged. The parameters above allow early identification of patients with a higher case fatality; these patients may benefit from being placed in a "high-risk" category early on in their management. Vaccination of the elderly may reduce the incidence and/or mortality from pneumococcal bacteraemia. Further studies are required to understand the reasons for referral for intensive therapy in acute pneumococcal bacteraemia and whether ITU management affects outcome.