Although underweight has been the traditional nutritional concern in patients with COPD, overweight and obesity are becoming important issues in this disease. In a rehabilitation study, investigators found that 66% of patients with moderate to severe COPD were either overweight or obese according to the WHO obesity classification (BMI ≥ 25 kg/m2). Obesity and COPD being two frequent conditions, it is important to understand the nature of their interactions.
Obesity, particularly in its visceral form is associated with a plethora of metabolic consequences that increases the risk of cardiovascular diseases. This would seem relevant to COPD which is in itself an important risk factor for cardiovascular diseases. The presence of obesity, particularly visceral obesity, may thus define in patients with COPD a clinical phenotype at high risk of cardiovascular diseases. In this context, it is relevant to note that the prevalence of metabolic syndrome is increased in COPD. Although fat distribution has not been precisely assessed in COPD studies, increased waist circumference is common in this disease suggesting that visceral obesity is part of the obesity syndrome seen in COPD.
Given the relationship between COPD, obesity and the metabolic syndrome and cardiovascular diseases, it is tempting to suggest that visceral obesity is likely to be frequent in COPD (as in the general population) and that the profound metabolic and inflammatory perturbations associated with this form of overweight/obesity could play a central role in the link between COPD and cardiovascular diseases.
Roflumilast, a Phosphodiesterase-4 inhibitor, has been recently evaluated as an anti-inflammatory medication in patients with COPD. Roflumilast, alone or in combination with long-acting bronchodilators, provide modest but significant improvement in lung function along with reductions in the rate of exacerbation in patients with moderate to severe COPD. A very interesting observation that was made in these 12-month duration studies was that the use of roflumilast was associated with an average reduction in body weight of 2 kg that took place during the first 6 months of the trials and remained relatively stable throughout the rest of the trials. The mechanisms and the precise effects of roflumilast on body composition and adipose tissue distribution have not been studied in great detail. However, available data suggest that roflumilast induces a preferential loss in body fat mass in comparison to fat-free mass. It remains to be seen whether roflumilast specifically affects visceral versus subcutaneous adipose tissue. The improved insulin sensitivity reported in one study in the presence of an apparently trivial weight loss (0.7 kg compared to placebo) may suggest that a selective loss of visceral adipose tissue may have been produced in response to roflumilast therapy.
These observations, although not definitive, suggest that roflumilast could be used not only to treat the respiratory component of COPD but also to modulate the metabolic aspect of this disease including visceral adiposity, features of the metabolic syndrome and significant co-morbidities of COPD.
