Outcome measures
To assess the changes in COPD disease burden from each cohort, demographics along with FEV1, smoking status, number of respiratory medications and exacerbations and comorbidities were collected by reviewing medical charts. As part of regular practice, nurse and physician visits and telephone contacts were also systematically recorded in the medical chart of COPD patients via a standardized form implemented in 2005. To assess the change in workload between 2006 (refers to 2005–2006) and 2009 (refers to 2008–2009), each visit or contact, in person or by telephone, was recorded based on the notes in the chart.