1. David Culliford, Lynn Josephs, Matthew Johnson, Mike Thomas
Are COPD outcomes different in patients who have also been diagnosed with asthma? A real-life UK cohort study
David Culliford, Lynn Josephs, Matthew Johnson, Mike Thomas
NIHR CLAHRC Wessex Methodological Hub and Department of Primary Care and Population Sciences
University of Southampton, Southampton, UK.

2. Background
Traditionally, COPD and asthma have been considered as separate diseases
Yet patients with COPD sometimes exhibit clinical features of asthma
Furthermore, early asthma may be followed by COPD later in life
Population-level data can be useful in exploring the differences in outcomes between COPD patients with and without asthma

3. Study Aims
To estimate the prevalence of diagnosed asthma in COPD patients in Hampshire, UK
To compare outcomes between COPD patients with and without a diagnosis of asthma
Outcomes:
All-cause mortality
Hospital admission (Respiratory cause)
Emergency department attendance (Respiratory cause)

4. The data - HHRA
Retrospective observational cohort study using individual patient-anonymised routine data held in the Hampshire Health Record Analytical database (HHRA)
An electronic NHS database
Routine clinical data
Over 140 practices
Around 1.4 million patients
Practice size: range 2192 to patients

5. Methods: Patients and outcomes
Read codes (UK classification system) used to:
Define a prevalent cohort with a practice diagnosis of COPD as at 31/12/2010
Within that COPD cohort, identify those with a diagnosis of asthma at any time prior to 01/01/2011
Assess smoking status, FEV1 %predicted, FEV1/FVC ratio, deprivation indices and comorbidities
Outcomes over 3 years: respiratory hospitalisation, respiratory ED attendance, all-cause mortality

6. COPD cohort
16479 patients (male 53.7%), mean (SD) age years (11.1)
Smoking status available for 97.4% of cohort
Current smokers 37.2%
Ex-smokers 57.7%
Never smokers 2.4%
FEV1 %predicted in 90%: mean (SD) 60.7 (20.1)
8621 (52.3%) COPD-only, 7858 with asthma (47.7%)
“… and almost half of this COPD cohort had been given a diagnosis of asthma at some time before the start of the study period.”

7. COPD cohort with/without asthma
“Those with asthma are more likely to be female (50% vs 43%), slightly younger (69.5 vs 70.7 years old). Also they are less likely to smoke (35% vs 40%) and more likely to have given up smoking (61% vs 57%)”

8. COPD cohort with/without asthma
“Those with asthma are more likely to be female (50% vs 43%), slightly younger (69.5 vs 70.7 years old). Also they are less likely to smoke (35% vs 40%) and more likely to have given up smoking (61% vs 57%)”

9. COPD cohort with/without asthma
“Those with asthma have slightly lower but similar FEV1, FEV1%predicted and FEV1/FVC ratio and a similar number of comorbidities.”

10. COPD cohort with/without asthma
“Those with asthma have slightly lower but similar FEV1, FEV1%predicted and FEV1/FVC ratio and a similar number of comorbidities.”

11. Outcomes with and without asthma
“These outcomes are as reported during the 3-year study period:
Similar proportion of deaths (12% vs 13%)
Higher proportion admitted to hospital (19% vs 16%)
Higher proportion attended an emergency department (10% vs 8%)

12. Outcomes – Adjusted analysis
Estimated increase/decrease in the odds of COPD patients with an asthma diagnosis experiencing the outcome against those without
“Here we see that there is no significant difference in the risk of dying, with or without an asthma diagnosis, but …”

13. Outcomes – Adjusted analysis
Estimated increase/decrease in the odds of COPD patients with an asthma diagnosis experiencing the outcome against those without
“Here we see that there is no significant difference in the risk of dying, with or without an asthma diagnosis, but …”

14. Conclusions
Almost half (48%) the COPD cohort had been given a diagnosis of asthma at some time
Those with asthma were: more likely to be female, slightly younger, less likely to smoke, more likely to have stopped smoking
Those with asthma had a 20%+ increased risk of hospital admission and of attending an emergency department, but no excess mortality risk
Asthma and COPD are heterogeneous conditions and both can be under and over diagnosed in primary care. Having a diagnosis of asthma was associated with a higher hospitalisation rate and we need to try and understand this better.

15. Acknowledgements
The research team would like to thank NHS South, Central and West Commissioning Support Unit and the Hampshire Health Record Information Governance Group for their support, and for the provision of access to HHRA data.
Last slide … supplementary slide(s) follow

16. Time since first asthma diagnosis
Supplementary slide:
“This bar chart shows, for the 8,000+ COPD patients also diagnosed with asthma, the distribution of years since first recorded diagnosis of asthma within age at start of the study.”
“We see that, almost irrespective of age, approximately half of these COPD patients were diagnosed with asthma within 10 years of the study beginning.”

17. Outcome distribution Respiratory cause hospital admissions
Percentage within group by number of admissions per patient (one or more)
“Here we see the distribution of the number of hospital admissions, remembering that 19.2% with and 16.3% without an asthma diagnosis had at least one admission.
“Those with an asthma diagnosis have a consistently higher proportion across the range …”

18. Outcome distribution Respiratory cause emergency department attendance
Percentage within group by number of admissions per patient (one or more)
“Similarly, we see the distribution of the number of emergency department attendances, remembering that 10.5% with and 8.7% without an asthma diagnosis had at least one ED attendance.
“Again, we see that those with an asthma diagnosis have a consistently higher proportion across the range …”
“Note that the two outcomes are not mutually exclusive – some of the hospital admissions were as result of an emergency department attendance.”