Obesity survival paradox in pneumonia: a meta-analysis.
BACKGROUND
It is unclear whether an 'obesity survival paradox' exists for pneumonia. Therefore, we conducted a meta-analysis to assess the associations between increased body mass index (BMI), pneumonia risk, and mortality risk.


METHODS
Cohort studies were identified from the PubMed and Embase databases. Summary relative risks (RRs) with their corresponding 95% confidence intervals (CIs) were calculated using a random effects model.


RESULTS
Thirteen cohort studies on pneumonia risk (n = 1,536,623), and ten cohort studies on mortality (n = 1,375,482) were included. Overweight and obese individuals were significantly associated with an increased risk of pneumonia (RR = 1.33, 95% CI 1.04 to 1.71, P = 0.02, I(2) = 87%). In the dose-response analysis, the estimated summary RR of pneumonia per 5 kg/m(2) increase in BMI was 1.04 (95% CI 1.01 to 1.07, P = 0.01, I(2) = 84%). Inversely, overweight and obese subjects were significantly associated with reduced risk of pneumonia mortality (RR = 0.83, 95% CI 0.77 to 0.91, P < 0.01, I(2) = 34%). The estimated summary RR of mortality per 5 kg/m(2) increase in BMI was 0.95 (95% CI 0.93 to 0.98, P < 0.01, I(2) = 77%).


CONCLUSIONS
This meta-analysis suggests that an 'obesity survival paradox' exists for pneumonia. Because this meta-analysis is based on observational studies, more studies are required to confirm the results.
Wei
W
Nie
Yi
Y
Zhang
Sun Ha
SH
Jee
Keum Ji
KJ
Jung
Department of Respiratory Medicine, Shanghai Changzheng Hospital, Second Military Medical University, 415 Fengyang Road, Shanghai 200003, China. lbxwzhao@gmail.com.
Bing
B
Li
Qingyu
Q
Xiu
D015992:Body Mass Index; D015331:Cohort Studies; D016001:Confidence Intervals; D016208:Databases, Factual; D005260:Female; D006801:Humans; D009765:Obesity / Q000150:complications / Q000401:mortality*; D064887:Observational Studies as Topic; D050177:Overweight / Q000150:complications / Q000401:mortality; D011014:Pneumonia / Q000150:complications / Q000401:mortality*; D012306:Risk; D040242:Risk Reduction Behavior