PT - JOURNAL ARTICLE AU - Ewig, S. AU - Torres, A. AU - Ángeles Marcos, M. AU - Angrill, J. AU - Rañó, A. AU - de Roux, A. AU - Mensa, J. AU - Martínez, J.A. AU - de la Bellacasa, J.P. AU - Bauer, T. TI - Factors associated with unknown aetiology in patients with community-acquired pneumonia AID - 10.1183/09031936.02.01942001 DP - 2002 Nov 01 TA - European Respiratory Journal PG - 1254--1262 VI - 20 IP - 5 4099 - https://publications.ersnet.org//content/20/5/1254.short 4100 - https://publications.ersnet.org//content/20/5/1254.full SO - Eur Respir J2002 Nov 01; 20 AB - Despite comprehensive diagnostic work-up, the aetiology of community-acquired pneumonia (CAP) remains undetermined in 30–60% of cases. The authors studied factors associated with undiagnosed pneumonia. Patients hospitalised with CAP and being evaluated by two blood cultures, at least one valid lower respiratory tract sample, and serology on admission were prospectively recorded. Patients who had received antimicrobial pretreatment were excluded. Patients with definite or probable aetiology were compared to those with undetermined aetiology by uni- and multivariable analysis. A total 204 patients were eligible for the study. The aetiology remained undetermined in 82 (40%) patients, whereas a definite aetiology could be established in 89 (44%) and a probable one in 33 (16%). In multivariable analysis, factors associated with undetermined aetiology included age >70 yrs, renal and cardiac comorbidity, and nonalveolar infiltrates on the chest radiograph. There was no association of undiagnosed pneumonia with mortality. Age and host factors were associated with unknown aetiology of community-acquired pneumonia. Some of these cases may also represent fluid volume overload mimicking pneumonia. This study was supported by Commisionat per a Universitats i Recerca de la Generalitat de Catalunya,1997 SGR 00086, IDIBAPS Hospital Clinic Barcelona, and FISS 98/0138.