Community-Acquired Meningitis in Older Adults
Objectives To investigate the epidemiology and outcomes of community-acquired meningitis in older adults.
Design Retrospective study.
Setting Participants adults in Houston, Texas, with community-acquired meningitis hospitalized between January 1, 2005, and January 1, 2010 (N = 619; n = 54, 8.7%, aged ≥65; n = 565 aged <65).
Methods An adverse clinical outcome was defined as a Glasgow Outcome Scale score of 4 or less.
Results Older adults had higher rates of comorbidities, abnormal neurological and laboratory (serum white blood cell count >12,000/μL, and cerebrospinal fluid protein >100 mg/dL) findings (P < .001), abnormalities on computed tomography and magnetic resonance imaging of the head (P = .002), and adverse clinical outcomes (ACOs) (P < .001). The majority of participants (65.8%) had meningitis of unknown etiology. Bacterial meningitis was an infrequent cause of community-acquired meningitis (7.4%). Of the known causes, bacterial meningitis and West Nile virus were more common in older than younger adults; younger participants more frequently had cryptococcal and viral meningitis. On logistic regression, female sex was predictive of a poor outcome in the older participants (P = .002), whereas abnormal neurological examination (P < .001), fever (P = .01), and a cerebrospinal fluid glucose level less than 45 mg/dL (P = .002) were significant poor prognostic factors in younger participants.
Conclusion Most cases of community-acquired meningitis are of unknown origin. Older adults are more likely than younger adults to have bacterial meningitis and West Nile virus infection when a cause can be identified. They also have more neurological abnormalities, laboratory and imaging abnormalities, and adverse clinical outcomes.
Community-acquired meningitis encompasses a broad range of infectious and noninfectious causes, but existing studies in older adults have predominately focused on bacterial meningitis. In recent decades, the epidemiology of meningitis has changed with the introduction of vaccines against Haemophilus influenzae type b and Streptococcus pneumoniae, the development of new diagnostic tools, and the discovery of new infectious etiologies, such as the West Nile virus. Changes in host factors also play an important role, as the population shifts toward a larger aging cohort and conditions emerge that compromise the immune system. As a result, older adults have become an increasingly more vulnerable group, with high rates of adverse outcomes.
Diagnosing meningitis in older adults presents a unique challenge because there is greater variability of disease presentation. The absence of consistent characteristic features can be misleading for diagnosticians, prompting the search for other causes and potentially delaying treatment. Bacterial meningitis is associated with high morbidity and mortality in older adults, but bacteria remain an uncommon cause of community-acquired meningitis, and few studies have described the characteristics of community-acquired meningitis in this older group. The purpose of this study was to expand the focus beyond bacterial meningitis to describe the etiologies and differences in clinical features, laboratory findings, and outcomes between older and younger individuals with community-acquired meningitis.
Abstract and Introduction
Abstract
Objectives To investigate the epidemiology and outcomes of community-acquired meningitis in older adults.
Design Retrospective study.
Setting Participants adults in Houston, Texas, with community-acquired meningitis hospitalized between January 1, 2005, and January 1, 2010 (N = 619; n = 54, 8.7%, aged ≥65; n = 565 aged <65).
Methods An adverse clinical outcome was defined as a Glasgow Outcome Scale score of 4 or less.
Results Older adults had higher rates of comorbidities, abnormal neurological and laboratory (serum white blood cell count >12,000/μL, and cerebrospinal fluid protein >100 mg/dL) findings (P < .001), abnormalities on computed tomography and magnetic resonance imaging of the head (P = .002), and adverse clinical outcomes (ACOs) (P < .001). The majority of participants (65.8%) had meningitis of unknown etiology. Bacterial meningitis was an infrequent cause of community-acquired meningitis (7.4%). Of the known causes, bacterial meningitis and West Nile virus were more common in older than younger adults; younger participants more frequently had cryptococcal and viral meningitis. On logistic regression, female sex was predictive of a poor outcome in the older participants (P = .002), whereas abnormal neurological examination (P < .001), fever (P = .01), and a cerebrospinal fluid glucose level less than 45 mg/dL (P = .002) were significant poor prognostic factors in younger participants.
Conclusion Most cases of community-acquired meningitis are of unknown origin. Older adults are more likely than younger adults to have bacterial meningitis and West Nile virus infection when a cause can be identified. They also have more neurological abnormalities, laboratory and imaging abnormalities, and adverse clinical outcomes.
Introduction
Community-acquired meningitis encompasses a broad range of infectious and noninfectious causes, but existing studies in older adults have predominately focused on bacterial meningitis. In recent decades, the epidemiology of meningitis has changed with the introduction of vaccines against Haemophilus influenzae type b and Streptococcus pneumoniae, the development of new diagnostic tools, and the discovery of new infectious etiologies, such as the West Nile virus. Changes in host factors also play an important role, as the population shifts toward a larger aging cohort and conditions emerge that compromise the immune system. As a result, older adults have become an increasingly more vulnerable group, with high rates of adverse outcomes.
Diagnosing meningitis in older adults presents a unique challenge because there is greater variability of disease presentation. The absence of consistent characteristic features can be misleading for diagnosticians, prompting the search for other causes and potentially delaying treatment. Bacterial meningitis is associated with high morbidity and mortality in older adults, but bacteria remain an uncommon cause of community-acquired meningitis, and few studies have described the characteristics of community-acquired meningitis in this older group. The purpose of this study was to expand the focus beyond bacterial meningitis to describe the etiologies and differences in clinical features, laboratory findings, and outcomes between older and younger individuals with community-acquired meningitis.
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