Lower incidence of acute respiratory distress syndrome in community-acquired pneumonia patients aged 85 years or older

Background and objective: The incidence of and risk factors for ARDS among elderly patients with community-acquired pneumonia (CAP) have not been well characterized. Methods: The clinical details of 221 consecutive patients aged >= 65 years, who were admitted with CAP during the period April 2006 to June 2008, were investigated by review of patient charts. Clinical variables and laboratory data at admission for CAP were compared between patients with and without ARDS. Results: Eighteen patients (8.1%) developed ARDS 1-5 days after admission. The mortality rate was 44% in patients with ARDS and 10.3% in those without ARDS (P < 0.001). The incidence of ARDS was 8.5-20% among patients aged < 85 years and 1.1% in patients aged >= 85 years (P < 0.001), while overall mortality rates were not significantly different among the age groups. Predictors for the development of ARDS included higher serum levels of CRP and glucose, lower PaO2/fraction of inspired O-2 (FiO(2)), PaCO2 and HCO3-, and the presence of systemic inflammatory response syndrome at admission. ARDS developed less frequently among patients with pneumonia associated with oropharyngeal aspiration (AP). Multivariate analysis indicated that lower age, serum glucose, pre-existence of systemic inflammatory response syndrome and non-oropharyngeal AP were significant risk factors for ARDS. The Pneumonia Severity Index and confusion, urea, respiratory rate, blood pressure, age >= 65 score were not correlated with the incidence of ARDS. Conclusions: Predictors for ARDS appeared to differ from the determinants of severity of CAP in the elderly. ARDS developed less frequently in patients aged >= 85 years and in those with oropharyngeal AP. It is important to identify subjects at high risk for ARDS upon admission and to observe them closely.