Chronic obstructive pulmonary disease (COPD) is a common, progressive respiratory disease with continuing loss of lung function and symptoms such as shortness of breath and cough. Acute exacerbations of COPD (AECOPD) are the sudden worsening of COPD symptoms for a short space of time. For most people, the disease can be controlled through the daily use of two long-acting drugs that are taken using an inhaler (dual therapy). For some people who continue to get AECOPD despite being on dual therapy, an additional long-acting drug is recommended (triple therapy). The effectiveness of triple therapy compared to dual therapy is not clear, as it seems to reduce AECOPD but increase pneumonia infection and not affect mortality. This study will use information from de-identified primary care records of COPD patients to compare AECOPD and mortality in patients who continue on dual therapy after AECOPD compared to patients who are given triple therapy. This study will also look at whether there are differences in prescribing triple therapy according to GP practice, and differences in pneumonia rates, lung function, Accident and Emergency (A&E) attendance, and other drug prescriptions. This study will help to assess the advice given in medical guidelines.
The NICE guidelines state that triple therapy should be considered in patients on dual long-acting beta-agonist (LABA) + long-acting muscarinic antagonist (LAMA) therapy who experience 1 severe exacerbation or 2 or more moderate to severe exacerbations per year. This is based on randomised controlled trial (RCT) evidence that found reductions in severe AECOPD, however these studies also found increases in pneumonia and no affect on mortality. We will therefore assess this recommendation in a population using routinely collected data comparing those eligible for triple therapy who remain on dual therapy to those who step up to triple therapy. We will use a retrospective cohort study design to assess the effect of triple therapy on the primary outcomes of severe AECOPD rate, moderate-severe AECOPD rate, and mortality, and the secondary outcomes of pneumonia rate, A&E attendances, Forced Expiratory Volume in 1 second (FEV1), breathlessness measured using the modified medical research council (mMRC) dyspnoea scale, and drug prescription, using Cox regression, multi-level linear regression and Poisson regression. Demographic variables, comorbidities, COPD baseline variables, and healthcare usage at baseline will be included as covariates in the model to reduce confounding. The study will incorporate trial evidence on the effectiveness on triple therapy using a Bayesian framework to help mitigate the impact of ‘confounding by indication’.
In order to holistically assess the impact of triple therapy vs dual therapy, we will look at a number of outcomes:
Mortality rate (all cause, COPD related, and cardiovascular disease (CVD) related); severe AECOPD rate (= number of hospitalisations for AECOPD); moderate and severe AECOPD rate; rate of pneumonia diagnosis ; change in lung function (FEV1); change in breathlessness (mMRC) (if allowed by the data); number of A&E visits for AECOPD; Prescription of additional chronic therapy (theophylline or other methylxanthines); maintenance OCS; macrolides (e.g. azithromycin, erythromycin); carbocysteine
Jennifer Quint - Chief Investigator - Imperial College London
Alexander Adamson - Corresponding Applicant - Imperial College London
Cosetta Minelli - Collaborator - Imperial College London
HES Accident and Emergency;HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation