Risk factors for mortality in patients with invasive pneumococcal disease in South Africa
Date
2008-07-17T08:37:12Z
Authors
Nyasulu, Peter Suwirakwenda
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Abstract
ABSTRACT
Introduction
Invasive pneumococcal disease (IPD) is an important cause of morbidity and
mortality in many parts of the world. It is estimated that pneumococcal disease
causes more than one million-childhood deaths every year and the burden of disease
is greater in developing countries. The main aim of this study was to analyze risk
factors associated with mortality in invasive pneumococcal disease in all ages in
South Africa.
Materials and Methods
We performed an analytical cross-sectional analysis of secondary data from
national population-based surveillance for invasive Streptococcus pneumoniae
infection in South Africa. The study period was 1 January 2003 to 31 December
2005, and the mortality analysis used a subset of laboratory-confirmed cases who
had a completed case report form and available mortality data. Multiple logistic
regression models were constructed to identify risk factors significantly associated
with the increased risk of death in patients with invasive pneumococcal disease.
Separate models were used to evaluate risk factors for death in patients with
meningitis and those with other IPD.
Results
There were 1154 (24%) cases of Streptococcus pneumoniae meningitis and 3736
(76%) cases of other invasive disease. The overall case fatality rate was 1360/4890
(27.8%) of which 911 (67%) patients died within 2 days of admission and 449
(33%) died between 2 days and 30 days of admission.
Variables associated with mortality in a logistic regression analysis of all IPD
patients included meningitis (OR 2.8, CI 1.9 – 3.9, P=<0.001), HIV-infection (OR
2.8, CI 1.6 – 4.6, P=<0.001), acute severe illness measured by Pitt bacteraemia
score >=4 (OR 4.7, CI 2.8 – 7.7, P=<0.001) and prior antibiotic use within 2 months before first positive culture (OR 2.1, CI 1.4 – 3.1, P=<0.001). In addition to this
children less than 1 year and adults ≥45 years were more likely to die compared to
other age groups. Patients from Western Cape Province were significantly less
likely to die (OR 0.27, CI 0.15 – 0.50, P=<0.001) compared to other provinces.
Amongst HIV-positive patients severe immunosuppression (low CD4+ count) was a
risk factor for death. Risk factors for death were similar in patients with other IPD
and meningitis except for HIV which was associated with death in the meningitis
group but not in the other IPD group. Antibiotic resistance and vaccine-serotype
disease were not associated with increased risk of death.
Discussion and Conclusions
IPD is associated with a high mortality in South Africa. Our findings of increased
risk of death in HIV-positive patients especially those with low CD4+ count are of
importance given the high prevalence of HIV amongst patients with IPD.
Introduction of the pneumococcal conjugate vaccine as part of the national expanded program for immunization (EPI) and ensuring access to antiretroviral
therapy for HIV-positive patients where indicated should be prioritized.
Description
Keywords
invasive pneumococcal disease, bacteraemia, meningitis, serotypes, antibiotic-resistance, HIV, mortality, surveillance