BACKGROUND: There has been an important increase in the use of nebulized ipratropium solution (NIS) in the ambulatory treatment of elderly patients with chronic airway disease. Since these are relatively expensive medications it is important to define the characteristics and the natural history of the patients who are started on this therapy and compare them with those of the patients started on ipratropium metered dose inhalers (IMDI) or oral theophyline (OT). METHODS: The study was done with the Quebec health insurance program (RAMQ database). The index date was the first dispensation of NIS (n=761), IMDI (n=3870) or OT (n=10355). The consumption of drugs and medical services was measured during the 12 months before the index date. RESULTS: At the time therapy was initiated, patients started on NIS had had more hospitalization days for chronic airway disease (NIS:2.97, IMDI:0.92, OT:0.12). They were also much heavier users of beta-agonists (NIS:13.53, IMDI:4.9, OT:0.11) and inhaled corticosteroids (NIS:4.63, IMDI:2.1, OT:0.37). The fact that patients started on NIS had a more advanced form of their chronic airway disease was confirmed by their much higher mortality rates (percent and 95% CI) during the 12 months following their index date (NIS: 17.2 (14.3-20.1), IMDI:8.3 (7.5-9.1), OT:4.9 (4.6-5.3). CONCLUSION: Patients are started on NIS when they have reached a very advanced form of their disease as shown by their very heavy use of beta-agonists and their high mortality rates.