Table 1

Inclusion and exclusion criteria for study population

  • Diagnostic Read code for COPD

  • Age ≥35 years

  • Spirometry recorded between 3 months before and 12 months after the first COPD diagnostic code (index date)

  • Evidence of obstruction ever recorded (FEV1/FVC<0.7)

  • Mild to moderate airflow limitation (FEV1 % predicted ≥50% and ≤90% at index date)

  • ≥1 year of up-to-standard* medical records prior to index date to enable baseline characterisation

  • History of smoking tobacco prior to first COPD diagnosis or at first recording after diagnosis

  • Height at adult age (≥21 years) and weight recorded within 5 years of index date

  • Up-to-standard* follow-up period covering ≥3 years between the first and last spirometry records

  • Active asthma at or after the date of first COPD diagnosis, defined as ≥1 diagnostic Read code for asthma or ≥1 asthma monitoring or review codes recorded, or asthma-COPD overlap syndrome as first COPD diagnostic code or recorded during follow-up

  • Diagnostic code for other chronic lower respiratory conditions ever recorded

  • Severe airflow limitation (FEV1 % predicted <50% at index date) as there is limited scope for further FEV1 decline and early intervention in these patients

  • *Up-to-standard data are of continuous high quality and considered suitable for research.