Predicting 2-Year Risk of Developing Pneumonia in Older Adults without Dementia

Abstract

Objectives: To develop three prognostic indices of varying degree of required detail for 2-year pneumonia risk in older adults.

Design: Retrospective cohort study.

Setting: Group Health (GH), an integrated healthcare delivery system.

Participants: Community-dwelling dementia-free individuals aged 65 and older who had been GH members for at least 2 years before start of follow-up and were enrolled in the Adult Changes in Thought study (N = 3,375; development cohort, n = 2,250; validation cohort, n = 1,125.

Measurements: Potential pneumonia risk factors were identified from questionnaire data and interviewer assessments of functional status, medical history, smoking and alcohol use, cognitive function, personal care, and problem solving. Risk factors were also identified based on physical measures such as grip strength and gait speed and administrative database information on comorbid illnesses, laboratory tests, and prescriptions dispensed. Incident community-acquired pneumonia was defined presumptively from administrative data and validated using medical record review.

Results: Participants (59% female) contributed 12,998 visits at which risk factors were assessed; 642 pneumonia events were observed during follow-up. Age, sex, chronic obstructive pulmonary disease, congestive heart failure, body mass index, and use of inhaled or oral corticosteroids were critical predictors in all prognostic indices. A risk score based on these seven variables, information on which is commonly available in electronic medical records (EMRs), had equal or better performance (c-index = 0.69 in the validation cohort) than scores including more-detailed data such as functional status.

Conclusion: Data commonly available in EMRs can stratify older adults into groups with varying subsequent 2-year pneumonia risk.

Keywords: aged 80 and older; pneumonia; predictive value of tests.

Figure 1

Predicted vs. observed two-year pneumonia risk in dementia-free older adults from two prediction models, across 50 imputed datasets. Light grey dots, pneumonia risk within the development cohort; dark grey dots, pneumonia risk within the validation cohort. (Top panel) Clinical model; (Bottom panel) Electronic Medical Record (EMR) model. Diagonal lines indicate perfect agreement between observed and predicted risk.

Figure 2

Pneumonia risk score vs. observed pneumonia risk in dementia-free seniors from two prediction models, across 50 imputed datasets. Light grey dots, pneumonia risk within the development cohort; dark grey dots, pneumonia risk within the validation cohort. (Top panel) Clinical risk score; (Bottom panel) Electronic Medical Record (EMR) risk score