Risk and protective factors related to mortality from pneumonia among middleaged and elderly community residents: the JACC Study.
BACKGROUND
There have been few systematic investigations into risk and protective factors for pneumonia related mortality for community residents. This study investigated these factors utilizing a large cohort study on Japanese community residents.


METHODS
Subjects, 110,792 individuals (aged 40-79 years) enrolled in 1988-1990, were followed until death, or when they moved away from the surveyed communities, or the end of 2003. Pneumonia death was defined following 480-486 (International Classification of Diseases, 9th Revision) or J12-J18 (10th Revision). Age-adjusted and multivariate hazard ratios were calculated along with 95% confidence intervals using the Cox proportional hazards model.


RESULTS
With 1,112,747 person-years of the study, a total of 1,246 persons died of pneumonia. We found history of blood transfusion (multivariate hazard ratio=2.0 [95% confidence interval: 1.7-2.4]) was a potent novel risk factor. Walking 0.5-1 hour/day (0.8 [0.6-1.0]), 1+ hour/day (0.7 [0.6-0.8]), and/or a history of pregnancy (0.6 [0.4-0.9]) were found to reduce pneumonia mortality. A large body mass index (BMI) (25+kg/m(2)) was a protective factor (0.7 [0.5-0.8]), while low BMI (<18) was confirmed as a risk one (2.1 [1.7-2.6]). Smoking was an important preventable risk factor (1.6 [1.3-1.9], population attributable risk proportion=14%), and its cessation reduced risk (0.7 [0.5-1.0]) to levels comparable to neversmokers (0.7 [0.5-1.0]).


CONCLUSIONS
The risk and protective factors ascertained here for pneumonia mortality among community residents, history of blood transfusion, large BMI, and walking habits, warrant further study. Smoking cessation may effectively reduce pneumonia mortality.
Inoue
Yusuke
Y
Department of Health and Environmental Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Koizumi
Akio
A
Wada
Yasuhiko
Y
Iso
Hiroyasu
H
Watanabe
Yoshiyuki
Y
Date
Chigusa
C
Yamamoto
Akio
A
Kikuchi
Shogo
S
Inaba
Yutaka
Y
Toyoshima
Hideaki
H
Tamakoshi
Akiko
A
D000328:Adult; D000367:Age Factors; D000368:Aged; D015331:Cohort Studies; D017714:Community-Acquired Infections; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011014:Pneumonia / Q000401:mortality*; D016016:Proportional Hazards Models; D012307:Risk Factors