Community-acquired lower respiratory tract infection in the elderly: a community-based study of incidence and outcome.

Abstract

We studied the incidence, characteristics, and survival of elderly patients from a defined community who had pneumonia or bronchitis (lower respiratory tract infection). This study was a population-based retrospective cohort study of residents of Rochester, Minnesota, aged 65 years or older with a first episode of pneumonia or bronchitis during the calendar year 1987. Overall age- and sex-adjusted incidence rates for an initial episode in a calendar year were 5452 per 100,000: 2420 per 100,000 (95 percent confidence interval, 2056 to 2783 per 100,000) for bronchitis and 3032 per 100,000 (95 percent confidence interval, 2639 to 3425 per 100,000) for pneumonia. After exclusion of eight cases diagnosed at autopsy, the overall 30-day mortality was 10.7 percent. Patients with pneumonia had lower survival than expected for the Minnesota white population (log-rank statistic = 117.38, P < 0.0001). The observed survival of patients with bronchitis was also significantly less than expected (log-rank statistic = 6.25, P = 0.012). Lower respiratory tract infections are common in the elderly. Most patients in this study were not hospitalized, and atypical presentations were not observed. Early mortality (30 days) was high. Among elderly patients with either pneumonia or bronchitis, the survival was lower than expected. This study confirmed the need for population-based studies, because more than two-thirds of patients would have been missed if only hospitalized patients were included.