Acute exacerbations of chronic obstructive pulmonary disease: Clinical history and effects on rate of recurrent events and risk of death

Date of ISAC Approval: 
Lay Summary: 
Chronic obstructive pulmonary disease (COPD) is a progressive disease of the lungs associated with reduced life expectancy and poorer quality of life. COPD is characterised by symptoms of breathlessness, cough, and production of sputum. People with COPD often have worsening of their symptoms, and this is often triggered by an infection. These worsenings are termed exacerbations. They may be treated by the patient's GP with antibiotics and steroids, however more serious events may require admission to hospital. Many COPD patients have one or two exacerbations per year, however some have many more exacerbations while others do not seem to have any at all. This study will use primary care data linked with hospital data to investigate how the frequency and severity of exacerbations relate to risk of future exacerbations and risk of death. This work will help doctors understand which of their patients may be at higher risk of hospital admission or death.
Technical Summary: 
People with chronic obstructive pulmonary disease (COPD) often have acute worsening of their symptoms, termed acute exacerbations of COPD (AECOPD). These may be treated in primary care or may require hospitalisation. Frequency of AECOPD is thought to be a stable trait over time, however this has not been investigated in a primary care cohort. Although others have studied the relationship between severe AECOPD (hospitalised) and risk of death in those with COPD, this relationship is not clear for moderate AECOPD (treated by GP). We hypothesise that there are a large portion of COPD patients who never exacerbate, and that long term risk of death increases with increasing number of baseline AECOPD and with AECOPD severity. Using linked CPRD-HES-ONS data, we will perform a cohort study to investigate the rates of AECOPD (moderate and severe) and death during follow-up by baseline AECOPD frequency (defined as first 12 months after observation start). In particular we will characterise the rate of AECOPD and death in COPD patients who do not seem to exacerbate during baseline period. We will also conduct three nested case-control analyses to investigate the impact of frequency and severity of AECOPD in the previous three years on risk of: 1) moderate AECOPD; 2) severe AECOPD; and 3) death.
Health Outcomes to be Measured: 
- rate of exacerbations of COPD - mortality

Dr Jennifer Quint - Chief Investigator - Imperial College London
Dr Hana Muellerova - Collaborator - Astra Zeneca Ltd - UK Headquarters
Kieran Rothnie - Corresponding Applicant - GSK
Professor Liam Smeeth - Collaborator - London School of Hygiene & Tropical Medicine (LSHTM)

HES A&E;HES Admitted;ONS;Patient IMD