Chronic obstructive pulmonary disease (COPD), also known as chronic bronchitis or emphysema is a lung disease often caused by smoking. It is very common and is becoming more common. It causes a huge burden to patients with respect to day-to-day symptoms and is associated with an increased risk of death compared to the general population. Many people with COPD have periods of acute deterioration, usually triggered by a chest infection, called an acute exacerbation. These exacerbations are associated with worsening symptoms, for example, increased shortness of breath, or increase in sputum and/or cough. Exacerbations are important to try and prevent and treat promptly because they worsen quality of life and are associated with hospitalisation and worsening in lung function and sometimes death. For this reason, lots of randomised controlled trials and observational studies using routinely collected electronic healthcare records have been undertaken to study exacerbations. Using routine electronic healthcare records to study exacerbations can be a challenge as there are several ways to find an exacerbation using different methods. In this study, we would like to explore how using different definitions for exacerbations of COPD affects studies and see if using different definitions which are commonly used in the literature leads to different results and if some of those results are less accurate than others. This will help us to recommend using certain methods to study exacerbations of COPD in the future and is important for making sure any studies done around exacerbations are as accurate as possible.
People with chronic obstructive pulmonary disease (COPD) experience episodes of acute worsening called exacerbations. Exacerbations are commonly studied in randomised controlled trials and routine electronic healthcare record data. However, there is not an easy way to determine an exacerbation and although validation studies have been done in the past, multiple definitions have been used in the literature. We would like to understand how this may introduce bias to a study and potentially lead to inaccurate results. We will use CPRD Aurum linked to ONS data and HES APC data to identify a population of people aged 40 years or older with a diagnosis of COPD. The study period will range from 01/01/2010 to the 01/01/2020.
Within this population we aim to investigate: 1) the yearly incidence rate of exacerbations over follow-up; 2) the proportion of patients who develop heart failure yearly in patients who exacerbate frequently over follow-up; 3) the relationship between baseline heart failure and risk of future exacerbations over follow-up using Cox regression; and 4) the incidence of exacerbations yearly in CPRD GOLD. For each aim we will use six commonly used definitions of exacerbations of COPD based on previously published literature to see the affect each definition has on results.
This study is of important public health benefit as it will help policy makers and guideline committees to better assess the accuracy of studies investigating COPD exacerbations.
Our outcome of interest will be exacerbations of COPD. We aim to define exacerbations of COPD in 6 different ways based on previously published literature and investigate how the use of different definitions may lead to different study results. Exacerbations will be defined in the following ways:
1. Exacerbation definition with the highest PPVs from a previous COPD validation study (definition 7 and 15 in figure 1 and 2) using primary care data [1] and identification of severe exacerbations using HES. This will be used to determine frequent exacerbators (those with two or more treated exacerbations per year).
2. Using the above definition but not including HES APC data to determine COPD exacerbation, only using primary care to determine hospitalisation.
3. Exacerbations defined using LTRI codes as well as prescribed oral corticosteroids and/or antibiotics following a previous definition [1,2].
4. Exacerbations defined using specific acute exacerbation of COPD code only in primary care
5. Oral corticosteroid prescriptions only following a previous definition [4].
6. Exacerbation defined using HES A&E and HES APC rather than just HES APC to identify severe exacerbations.
Jennifer Quint - Chief Investigator - Imperial College London
Hannah Whittaker - Corresponding Applicant - Imperial College London
Kieran Rothnie - Collaborator - GlaxoSmithKline Services Unlimited (UK)
HES Accident and Emergency;HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation