Body mass index and mortality in chronic obstructive pulmonary disease: a meta-analysis

PLoS One. 2012;7(8):e43892. doi: 10.1371/journal.pone.0043892. Epub 2012 Aug 24.


Background: The association between body mass index (BMI) and mortality in patients suffering from chronic obstructive pulmonary disease (COPD) has been a subject of interest for decades. However, the evidence is inadequate to draw robust conclusions because some studies were generally small or with a short follow-up.

Methods: We carried out a search in MEDLINE, Cochrane Central Register of Controlled Trials, and EMBASE database for relevant studies. Relative risks (RRs) with 95% confidence interval (CI) were calculated to assess the association between BMI and mortality in patients with COPD. In addition, a baseline risk-adjusted analysis was performed to investigate the strength of this association.

Results: 22 studies comprising 21,150 participants were included in this analysis. Compared with patients having a normal BMI, underweight individuals were associated with higher mortality (RR = 1.34, 95% CI = 1.01-1.78), whereas overweight (RR = 0.47, 95% CI = 0.33-0.68) and obese (RR = 0.59, 95% CI = 0.38-0.91) patients were associated with lower mortality. We further performed a baseline risk-adjusted analysis and obtained statistically similar results.

Conclusion: Our study showed that for patients with COPD being overweight or obese had a protective effect against mortality. However, the relationship between BMI and mortality in different classes of obesity needed further clarification in well-designed clinical studies.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Body Mass Index*
  • Body Weight*
  • Humans
  • Obesity / complications
  • Obesity / mortality
  • Overweight / complications
  • Overweight / mortality
  • Prognosis
  • Pulmonary Disease, Chronic Obstructive / complications
  • Pulmonary Disease, Chronic Obstructive / mortality*
  • Thinness / complications
  • Thinness / mortality

Grants and funding

This work is supported by research grants from Clinical academic key funds of the Chinese Ministry of Health (2007353) and special funds for scientific research on public causes of the Chinese Ministry of Health (201002008). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.