Medical research studies and daily clinical practice show that chronic obstructive pulmonary disease (COPD) can evolve very differently in patients, with distinct patterns of symptoms, X-ray findings, lung function decline and response to medical treatment.
Episodes when the disease suddenly becomes worse (exacerbations) are critical events in a person's history of COPD. These events worsen quality of life and lung function and increase the probability of death. Within UK general practice, around a quarter of COPD patients have very stable disease over time, without any exacerbations up to ten years. We think that COPD patients without these exacerbations are a specific group, and we want to find out what characterises them so that we can better understand how to determine which patients are at higher risk so that they can be managed.
Chronic obstructive pulmonary disease (COPD) has proven to be a heterogeneous disease with regard to symptoms, radiological findings, type of inflammatory response, response to inhaled corticosteroids and comorbidities. However, it is especially the frequency and severity of acute exacerbations of COPD (AECOPD), which shapes lung function trajectories and survival.
Recent data points at a large subgroup of COPD patients less susceptible to exacerbation, and this trait appears to be stable over time for periods as long as ten years. Little is known about the nature of this non-exacerbating phenotype even though one out of four COPD patients seems to belong to this category.
Our design will include as a first part a cross sectional study describing the clinical characteristics of non-exacerbating COPD patients, such as general demographics, degree of dyspnoea, severity of obstruction by spirometry, smoking history, medication, previous or concomitant other lung diseases and other comorbidities. We will then conduct a historical cohort study aiming at comparing mortality rates between non-exacerbating and exacerbating COPD patients as well as causes of death in both groups. Non-exacerbating COPD patients will be defined through a baseline period of three years after inclusion, with no exacerbation during this time. Cox proportional hazards regression will be used. As primary care is the management setting for most COPD patients, the Clinical Practice Research Database (CPRD) should be a representative source of data for our study.
1. Clinical characteristics of non-exacerbating compared to exacerbating COPD patients, such as general demographics, degree of dyspnoea, severity of obstruction at spirometry, smoking history, medication, previous or concomitant other lung diseases and other comorbidities
2. Mortality rates and causes of death in non-exacerbating compared to exacerbating COPD patients
3. Health care utilisation
Jennifer Quint - Chief Investigator - Imperial College London
Alexandra Lenoir - Corresponding Applicant - Imperial College London
Debbie Jarvis - Collaborator - Imperial College London
HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation