Outpatients with tracheostomy can be managed with a low risk for severe airways infections despite colonization with pathogenic bacteria. No studies have been focused on chronic obstructive pulmonary disease (COPD), a condition known for recurrent exacerbations. The aim of our study was to verify whether at follow-up in tracheostomized COPD versus other disease outpatients, persistent P. aeruginosa colonization may influence the rate and treatment of lower respiratory tract infections (LRTI) or hospital admissions. Thirty-nine outpatients were considered: 24 were affected by COPD (age 66, 54-78 years, mean, range), 15 by restrictive lung disease (RLD) (57, 41-72 years). During an 18-month follow-up the number of LRTIs were recorded. Bacterial identifications were assessed at baseline and every month for 6 months in bronchial aspirates. The number of LRTI per patient was not significantly different between COPD [37, 1(0-6)] and RLD [18, 1(0-5)], [total, median (range)]. Persistent P. aeruginosa colonized 18 COPD (75%), 12 RLD patients (86%) and was not associated with an increased number of LRTI: 1(0-6) and 1(0-2), respectively. There were no differences in the number of hospital admissions: COPD 0(0-2), RLD 1(0-1), with a significant decrease versus before tracheostomy (P < 0.001). In conclusion, the rate of LRTI and hospital admissions in COPD outpatients with chronic tracheostomy was low, similar to non-COPD patients and independent of P. aeruginosa colonization.