Risk factors for the isolation of <i>Haemophilus influenzae</i> in patients with stable chronic obstructive pulmonary disease

<sec><title>INTRODUCTION</title>The risk factors associated with <i>Haemophilus influenzae</i> infection in patients with chronic obstructive pulmonary disease (COPD) outside of an exacerbation process are unknown. The objective of the present study is to analyse these risk factors.</sec><sec><title>METHODS</title>Multicentre, prospective study in 201 patients with moderate-severe COPD included between January 2004 and February 2007 and followed for a median of 84 months (between January 2004 and February 2007 with protocolised collection of clinical, comorbidities, analytical, functional, microbiological and therapeutic data, with a medical visit every 3-6 months. Factors independently associated with <i>H. influenzae</i> isolation during follow-up were calculated using logistic regression.</sec><sec><title>RESULTS</title>A total of 517 valid sputum samples were collected (23.6% positive for <i>H. influenzae</i>). The isolation of <i>H. influenzae</i> was independently associated with the accumulated smoking habit (in pack-years: HR 1.31, 95% CI 1.12-1.42), the number of severe exacerbations in the year prior to inclusion (HR 1.65, 95% CI 1.24-2.18) and the percentage value of forced expiratory volume in one second (HR 0.96, 95% CI 0.93-0.98)</sec><sec><title>CONCLUSION</title>Smoking habit, severe exacerbations and the degree of airflow obstruction are associated with the isolation of <i>H. influenzae</i> in sputum in patients with stable COPD.</sec>.