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Review
. 2014 Apr 10:12:61.
doi: 10.1186/1741-7015-12-61.

Obesity survival paradox in pneumonia: a meta-analysis

Wei Nie, Yi Zhang, Sun Ha Jee, Keum Ji Jung, Bing Li  1 , Qingyu Xiu
Affiliations
Review

Obesity survival paradox in pneumonia: a meta-analysis

Wei Nie et al. BMC Med. .

Abstract

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.

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Figures

Figure 1
Figure 1
Flow of study identification, inclusion and exclusion.
Figure 2
Figure 2
Relative risks of pneumonia risk per 5 kg/m2 increase in body mass index. CI: indicates confidence interval; and RR: risk ratio.
Figure 3
Figure 3
Dose–response relationship between body mass index and relative risk of pneumonia. Body mass index was modeled with a nonlinear trend (black continuous line) in a random effects meta-regression model. Long-dashed black lines represent 95% confidence intervals. Short-dashed black lines represent the linear trend. The vertical axes are on a log scale.
Figure 4
Figure 4
Relative risks of pneumonia mortality risk per 5 kg/m2increase in body mass index. CI: indicates confidence interval; and RR: risk ratio.
Figure 5
Figure 5
Dose–response relationship between body mass index and relative risk of pneumonia mortality. Body mass index was modeled with a nonlinear trend (black continuous line) in a random effects meta-regression model. Long-dashed black lines represent 95% confidence intervals. Short-dashed black lines represent the linear trend. The vertical axes are on a log scale.
See this image and copyright information in PMC

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