Impaired lung function as an important risk factor for blood stream infections

Background The association of impaired lung function with blood stream infections has only been studied for a limited number of pathogens. We tested the hypothesis that impaired lung function is independently associated with higher risk of any blood stream infections and by specific pathogens in the general population. Methods Copenhagen General Population Study participants had spirometry performed at baseline and were followed for up to 10 years with linkage to the Danish Microbiology Database. The 10-year absolute risk, multivariable adjusted hazard ratio (HR), and population attributable fraction for blood stream infections were determined according to impaired lung function. Outcomes were any and pathogen-specific blood stream infections. Results In 118,565 participants, we identified 4160 blood stream infections among 3438 individuals during 950,718 person-years of follow-up. The HR was 1.5 (95% confidence interval (CI), 1.4-1.7) for individuals with obstructive spirometric pattern and 1.4 (95% confidence interval (CI), 1.2-1.5) for individuals with PRISm. The HR for blood stream infections were 1.4 (95% CI: 1.3-1.6) for forced expiratory volume 1-second (FEV1) 50–79% predicted and HR 2.5 (95% CI: 2.0-3.2) for FEV1 below 50% of predicted. A similar pattern was seen for all pathogen specific blood stream infections. The 10-year risk of blood stream infections was 5.4.3% (95% CI: 5.1-5.9) and 4.3% (95% CI: 3.9–4.7) for individuals with PRISm and obstructive spirometric pattern, respectively. The population-attributable fraction of blood stream infections attributable to abnormal spirometric pattern was 9.5% (95% CI: 6.4%-12.7%). Conclusion Impaired lung function is an important risk factor for blood stream infections and not limited to respiratory tract pathogens.