MedWire News: Study results show that adult asthmatics of working age are at significantly greater risk for invasive pneumococcal infection (IPI) than the general population.
The findings suggest that asthma should be added to the list of indications for pneumococcal vaccination, say J Pekka Nuorti (Centers for Disease Control and Prevention, Atlanta, Georgia, USA) and colleagues.
Writing in the journal Thorax, the researchers explain: "Chronic obstructive pulmonary diseases (COPDs) are established risk factors for IPI, but there has been uncertainty as to whether persons with asthma… are at increased risk and if they should be vaccinated with pneumococcal polysaccharide vaccine."
To investigate the risk for IPI among asthmatics, the team studied data from a Finnish national surveillance program on 1282 patients with an IPI (Streptococcus pneumonia isolated from blood or cerebrospinal fluid) who were treated between 1995 and 2002. For each patient, 10 controls (total= 12,785) matched on age, gender, and health district of residence were randomly selected from the National Population Information System.
The researchers note that the analysis was limited to patients aged 18-49 years to reduce confounding caused by the presence of chronic obstructive pulmonary disease, which tends to develop in older individuals.
All participants with asthma were identified using data from health registries. Patients with high-risk asthma (HRA) were defined as those who required hospitalization for their condition within the past 12 months, while those with low-risk asthma (LRA) were defined as those who were entitled to prescription drugs for their condition, but who had not been hospitalized during the past 12 months.
Overall, 7.1% of IPI patients had asthma compared with just 2.5% of controls, including 6.0% and 2.4% with LRA, and 1.1% and 0.1% with HRA, respectively.
After accounting for potential confounding factors, such as the presence of other medical conditions, the researchers found that LRA and HRA were significantly associated with an increased risk for IPI, at odds ratios of 2.8 and 12.3, respectively.
The adjusted population-attributable risk was 0.04 for LRA and 0.01 for HRA, the researchers note.
Nuorti and team conclude: "This population-based study provides further evidence to support an association between asthma and IPI and suggests that, in addition to persons who require hospitalization and prolonged oral corticosteroid treatment for HRA, those with LRA are also at increased risk of IPI, supporting adding medically treated asthma in adults to the list of indications for pneumococcal vaccination."
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