COPD Exacerbator Phenotype is Inversely Associated with Current Smoking But Not with Haptoglobin Phenotype

Frequent chronic obstructive pulmonary disease (COPD) exacerbators are at a higher risk of adverse health outcomes when compared to infrequent exacerbators. A COPD frequent exacerbator phenotype and its definition has been reported. Haptoglobin (Hp) polymorphism has been associated with differing clinical outcomes in cardiovascular and renal disease. The Hp 2-2 phenotype has been found to have bacteriostatic properties, while the Hp 1-1 phenotype was found to be associated with infections.

To determine the correlation in haptoglobin phenotypes and the frequent exacerbator status compared to COPD non-exacerbators.

Inclusion criteria included previous diagnosis of COPD and presence of at least two documented exacerbations of COPD in the previous 12 months (frequent exacerbator group) or absence of such exacerbations in the previous 24 months (non-exacerbator group). Descriptive data was analyzed using Fisher's exact test and the nonparametric Kruskal-Wallis test. Multivariate logistic regression analysis was performed.

The multivariate logistic regression yielded a model in which haptoglobin phenotype did not have a statistically significant association with frequent exacerbator status. Smoking status was found to be negatively related with the frequent exacerbator status (odds ratio [OR] 0.240, 95% confidence interval (95%CI) 0.068-0.843, P = 0.03). Number of pack-years was negatively related to being a frequent exacerbator (OR 0.979, 95%CI 0.962-0.996, P = 0.02).

We found no relationship between haptoglobin polymorphism and frequent exacerbator status. However, frequent exacerbator status had a statistically significant association with COPD Assessment Test scores and pack-years and a negative correlation with current smoking status.