@article {6285, title = {Bidirectional relationship between cognitive function and pneumonia.}, journal = {Am J Respir Crit Care Med}, volume = {188}, year = {2013}, month = {2013 Sep 01}, pages = {586-92}, abstract = {

RATIONALE: Relationships between chronic health conditions and acute infections remain poorly understood. Preclinical studies suggest crosstalk between nervous and immune systems.

OBJECTIVES: To determine bidirectional relationships between cognition and pneumonia.

METHODS: We conducted longitudinal analyses of a population-based cohort over 10 years. We determined whether changes in cognition increase risk of pneumonia hospitalization by trajectory analyses and joint modeling. We then determined whether pneumonia hospitalization increased risk of subsequent dementia using a Cox model with pneumonia as a time-varying covariate.

MEASUREMENTS AND MAIN RESULTS: Of the 5,888 participants, 639 (10.9\%) were hospitalized with pneumonia at least once. Most participants had normal cognition before pneumonia. Three cognition trajectories were identified: no, minimal, and severe rapid decline. A greater proportion of participants hospitalized with pneumonia were on trajectories of minimal or severe decline before occurrence of pneumonia compared with those never hospitalized with pneumonia (proportion with no, minimal, and severe decline were 67.1\%, 22.8\%, and 10.0\% vs. 76.0\%, 19.3\%, and 4.6\% for participants with and without pneumonia, respectively; P < 0.001). Small subclinical changes in cognition increased risk of pneumonia, even in those with normal cognition and physical function before pneumonia (β = -0.02; P < 0.001). Participants with pneumonia were subsequently at an increased risk of dementia (hazard ratio, 2.24 [95\% confidence interval, 1.62-3.11]; P = 0.01). Associations were independent of demographics, health behaviors, other chronic conditions, and physical function. Bidirectional relationship did not vary based on severity of disease, and similar associations were noted for those with severe sepsis and other infections.

CONCLUSIONS: A bidirectional relationship exists between pneumonia and cognition and may explain how a single episode of infection in well-appearing older individuals accelerates decline in chronic health conditions and loss of functional independence.

}, keywords = {Aged, Cognition Disorders, Dementia, Female, Hospitalization, Humans, Longitudinal Studies, Male, Neuropsychological Tests, Pneumonia, Proportional Hazards Models, Risk Factors}, issn = {1535-4970}, doi = {10.1164/rccm.201212-2154OC}, author = {Shah, Faraaz Ali and Pike, Francis and Alvarez, Karina and Angus, Derek and Newman, Anne B and Lopez, Oscar and Tate, Judith and Kapur, Vishesh and Wilsdon, Anthony and Krishnan, Jerry A and Hansel, Nadia and Au, David and Avdalovic, Mark and Fan, Vincent S and Barr, R Graham and Yende, Sachin} } @article {6193, title = {Epidemiology and long-term clinical and biologic risk factors for pneumonia in community-dwelling older Americans: analysis of three cohorts.}, journal = {Chest}, volume = {144}, year = {2013}, month = {2013 Sep}, pages = {1008-1017}, abstract = {

BACKGROUND: Preventing pneumonia requires better understanding of incidence, mortality, and long-term clinical and biologic risk factors, particularly in younger individuals.

METHODS: This was a cohort study in three population-based cohorts of community-dwelling individuals. A derivation cohort (n = 16,260) was used to determine incidence and survival and develop a risk prediction model. The prediction model was validated in two cohorts (n = 8,495). The primary outcome was 10-year risk of pneumonia hospitalization.

RESULTS: The crude and age-adjusted incidences of pneumonia were 6.71 and 9.43 cases/1,000 person-years (10-year risk was 6.15\%). The 30-day and 1-year mortality were 16.5\% and 31.5\%. Although age was the most important risk factor (range of crude incidence rates, 1.69-39.13 cases/1,000 person-years for each 5-year increment from 45-85 years), 38\% of pneumonia cases occurred in adults \< 65 years of age. The 30-day and 1-year mortality were 12.5\% and 25.7\% in those \< 65 years of age. Although most comorbidities were associated with higher risk of pneumonia, reduced lung function was the most important risk factor (relative risk = 6.61 for severe reduction based on FEV1 by spirometry). A clinical risk prediction model based on age, smoking, and lung function predicted 10-year risk (area under curve [AUC] = 0.77 and Hosmer-Lemeshow [HL] C statistic = 0.12). Model discrimination and calibration were similar in the internal validation cohort (AUC = 0.77; HL C statistic, 0.65) but lower in the external validation cohort (AUC = 0.62; HL C statistic, 0.45). The model also calibrated well in blacks and younger adults. C-reactive protein and IL-6 were associated with higher pneumonia risk but did not improve model performance.

CONCLUSIONS: Pneumonia hospitalization is common and associated with high mortality, even in younger healthy adults. Long-term risk of pneumonia can be predicted in community-dwelling adults with a simple clinical risk prediction model.

}, keywords = {Age Factors, Aged, Aged, 80 and over, Community-Acquired Infections, Comorbidity, Female, Follow-Up Studies, Hospitalization, Humans, Incidence, Male, Middle Aged, Pneumonia, Prognosis, Prospective Studies, Risk Assessment, Risk Factors, Survival Rate, Time Factors}, issn = {1931-3543}, doi = {10.1378/chest.12-2818}, author = {Yende, Sachin and Alvarez, Karina and Loehr, Laura and Folsom, Aaron R and Newman, Anne B and Weissfeld, Lisa A and Wunderink, Richard G and Kritchevsky, Stephen B and Mukamal, Kenneth J and London, Stephanie J and Harris, Tamara B and Bauer, Doug C and Angus, Derek C} }