Risk factors for community-acquired pneumonia in immunocompetent seniors

To identify risk factors for developing community-acquired pneumonia (CAP) in seniors.

Nested case-control study.

Group Health, a health maintenance organization in Washington state.

One thousand one hundred seventy-three immunocompetent seniors with CAP and 2,346 age- and sex-matched controls, sampled during influenza seasons and pre-influenza periods of 2000/01 and 2002/03. CAP cases were presumptively identified according to diagnosis codes assigned to outpatient and inpatient encounters and validated according to review of chest radiograph reports or medical records.

Medical records were used to assess body mass, the presence and severity of cardiopulmonary and other chronic diseases, and the presence of functional or cognitive impairments. Use of prescription medications and inpatient, outpatient, and home medical services were identified from administrative databases.

Independent predictors of CAP include the presence and severity of cardiopulmonary disease, low weight and recent weight loss, and poor functional status; 42.0% of pneumonia cases can be attributed to underlying cardiopulmonary disease.

Seniors with cardiopulmonary disease, poor functional status, low weight, or recent weight loss have a greater risk of developing CAP. Preventative efforts should be targeted toward these individuals.