Epidemiology of community-acquired pneumonia in older adults: a population-based study

Abstract

Objective: This study assessed incidence, aetiology, clinical outcomes and risk factors for community-acquired pneumonia (CAP) in older adults.

Methods: This was a population-based cohort study that included 11,241 community-dwelling individuals aged 65 years or more, who were followed between 2002 and 2005 in the region of Tarragona, Spain. Primary endpoints were all-cause CAP (hospitalised and outpatient) and 30-day mortality after the diagnosis. All cases were radiographically proved and validated by checking clinical records.

Results: Incidence rate of overall CAP was 14 cases per 1000 person-years (10.5 and 3.5 for hospitalised and outpatient cases, respectively). Incidence was almost three-fold higher among immunocompromised patients (30.9 per 1000) than among immunocompetent subjects (11.6 per 1000). Maximum incidences were observed among patients with chronic lung disease and long-term corticosteroid therapy (46.5 and 40.1 cases per 1000 person-years, respectively). Overall 30-day case-fatality rate was 12.7% (2% in cases managed as outpatient and 15% in hospitalised patients). Among 358 patients with an aetiological work-up, a total of 142 pathogens were found (single pathogen in 121 cases and mixed pathogens in 10 cases). Streptococcus pneumoniae was the most common pathogen (49%), followed by Pseudomonas aeruginosa (15%), Chlamydia pneumoniae (9%) and Haemophilus influenzae (6%). In multivariable analysis, the variables most strongly associated with increasing risk of CAP were history of hospitalisation for CAP in the previous 2 years and presence of any chronic lung disease.

Conclusions: CAP remains a major cause of morbidity and mortality in older adults. Incidence rates in this study largely doubled prior rates reported in Southern European regions.