What happens between first symptoms and first acute exacerbation of COPD – observational study of routine data and patient survey
Authors: Bottle Alex , Adamson Alex , Zhang Xiubin , Hayhoe Benedict , K Quint Jennifer 
Published: November 2024

Background
Chronic obstructive pulmonary disease affects nearly 400 million worldwide – over a million in the United Kingdom – and is the third leading cause of death. However, there is limited understanding of what prompts a diagnosis, how long this takes from symptom onset and the different approaches to clinical management by primary care professionals.

Objectives
Map out the clinical management and National Health Service contacts from symptom presentation to chronic obstructive pulmonary disease diagnosis and first acute exacerbation of chronic obstructive pulmonary disease in three time periods; construct risk prediction for first acute exacerbation of chronic obstructive pulmonary disease.

Design
Retrospective cohort study and cross-sectional survey.

Setting
Primary care.

Participants
Patients with incident chronic obstructive pulmonary disease aged > 35 years in England.

Interventions
None.

Main outcome measures
First acute exacerbation of chronic obstructive pulmonary disease.

Data sources
Clinical Practice Research Datalink Aurum; new online survey.

Results
Forty thousand five hundred and seventy-seven patients were diagnosed between April 2006 and March 2007 (cohort 1), 48,249 between April 2016 and March 2017 (cohort 2) and 4752 between March and August 2020 (cohort 3). The mean (standard deviation) age was 68.3 years (12.0); 47.3% were female. Around three-quarters were diagnosed in primary care, with a slight fall in cohort 3. Compliance with National Institute for Health and Care Excellence diagnostic guidelines was slightly higher in cohorts 2 and 3 for all patients; 35.8% (10.0% in the year before diagnosis) had all four elements met for all cohorts combined. Multilevel modelling showed considerable between-practice variation in spirometry. The survey on the charity website had 156 responses by chronic obstructive pulmonary disease patients. Many respondents had not heard of the condition, hoped the symptoms would go away and identified various healthcare-related barriers to earlier diagnosis. Clinical Practice Research Datalink analysis showed notable changes in post-diagnosis prescribing from cohort 1 to 2, such as increases in long-acting muscarinic antagonist (21.7–46.3%). Triple therapy rose from 2.9% in cohort 2 to 11.1% in cohort 3. Documented pulmonary rehabilitation rose from just 0.8% in cohort 1 to 13.7% in cohort 2 and 20.9% in cohort 3. For all patients combined, the median time to first acute exacerbation of chronic obstructive pulmonary disease in patients who had one was 1.4 years in cohorts 1 and 2. Acute exacerbation of chronic obstructive pulmonary disease prediction models identified some consistent predictors, such as age, deprivation, severity, comorbidities, post-diagnosis spirometry and annual review. Models without post-diagnosis general practitioner actions had a c-statistic of around 0.70; the highest c-statistic was 0.81, for cohort 2 with post-diagnosis general practitioner actions and 6-month follow-up. All models had good calibration. The three most important predictors in terms of their population attributable risks were being a current smoker and offered smoking cessation advice (32.8%), disease severity (30.6%) and deprivation (15.4%). The highest population attributable risks for variables with adjusted hazard ratios < 1 were chronic obstructive pulmonary disease review (–27.3%) and flu vaccination (–26.6%).

Limitations
Symptom recording and chronic obstructive pulmonary disease diagnosis vary between practice; predicted forced expiratory volume in 1 second had many missing values.

Conclusions
There has been some improvement over time in chronic obstructive pulmonary disease diagnosis and management, with large changes in prescribing, though patient and system barriers to further improvement exist. Data available to general practitioners cannot generate risk prediction models with sufficient accuracy.

Future work
It will be important to expand the COVID-era cohort with longer follow-up and augment general practitioner data for better prediction.

Study registration
This study is registered as Researchregistry.com: researchregistry4762.

Funding
This award was funded by the National Institute for Health and Care Research (NIHR) Health and Social Care Delivery Research programme (NIHR award ref: 17/99/72) and is published in full in Health and Social Care Delivery Research; Vol. 12, No. 43. See the NIHR Funding and Awards website for further award information.