The burden of pneumococcal disease is measured only through patients with invasive pneumococcal disease. The urinary antigen test (UAT) for pneumococcus has exhibited a high sensitivity and specificity. We aimed to compare the pneumococcal pneumonias diagnosed as invasive disease with pneumococcal pneumonias defined by UAT.
Prospective observational study on consecutive non-immunosuppressed patients with community-acquired pneumonia from January 2000 to December 2014. Patients were stratified in 2 groups: Invasive pneumococcal pneumonia (IPP) defined as a positive blood culture or pleural fluid culture and non-invasive pneumococcal pneumonia (NIPP) defined as a positive UAT with blood or pleural fluid culture negative.
We analyzed 779 (15%) patients out of 5,132 where 361 (46%) had IPP and 418 (54%) were NIPP. Compared with IPP cases, the NIPP cases presented more frequent chronic pulmonary disease and received previous antibiotics more frequently. IPP patients presented more severe CAP, higher inflammatory markers and worse oxygenation at admission, more pulmonary complications, greater extrapulmonary complications, longer time to clinical stability and longer length of hospital stay compared to NIPP group. Age, chronic liver disease, mechanical ventilation and acute renal failure were independent risk factors for 30-day crude mortality. Neither IPP nor NIPP were an independent risk factor for 30-day mortality.
A high percentage of confirmed pneumococcal pneumonia is diagnosed by UAT. Despite differences in clinical characteristics and outcomes, IPP is not an independent risk factor for 30-day mortality compared with NIPP, reinforcing the importance of NIPP for pneumococcal pneumonia.