Rheumatoid arthritis is an inflammatory disease that primarily affects the joints but it can also affect other parts of the body. Of all the “outside-the-joints” manifestations of rheumatoid arthritis, lung problems are by far the most common and potentially the most serious. Among the lung problems associated with rheumatoid arthritis, interstitial lung disease – a condition which is characterised by scarring or “fibrosis” of the lung – is the most feared as it often leads to early death. Unfortunately, once established, lung fibrosis cannot be reversed and in many people it simply gets worse over time and as their breathing problems worsen so does their quality of life.
This study will look at the development of lung fibrosis in people with rheumatoid arthritis. Establishing a diagnosis in people with rheumatoid arthritis can be tricky. Patients typically first complain of breathlessness and cough, which may initially be attributed by their GP to the more usual causes of these symptoms, namely other lung diseases or heart failure. For this reason, delays in the diagnosis of fibrosis in people with rheumatoid arthritis are extremely common.
The purpose of this study is to estimate how long it takes on average for an individual to get a diagnosis of fibrosis when they also have rheumatoid arthritis. We will also explore what possible misdiagnoses may have preceded the eventual diagnosis of fibrosis, what medications may have been given along the way, and what consequences delayed diagnosis might be having on patient survival and other health outcomes.
It has been estimated that up to 20% of people with rheumatoid arthritis (RA) develop interstitial lung disease (ILD). Timely and accurate diagnosis of RA-associated-ILD is critical as early introduction of therapy may help reduce the risk of irreversible lung function decline in this patient group, and in so doing, improve quality of life and prognosis. However, as breathlessness is a common symptom in patients with autoimmune conditions such as RA, establishing a diagnosis of ILD can be challenging and thus misdiagnoses and diagnostic delays are extremely common.
A key objective of this study is to quantify the delays in reaching a diagnosis of ILD in patients with RA using HES/DID/ONS/IMD linked primary care records (Aurum). In terms of characterising and describing diagnostic delays, we will consider both the overall delay, that is the time elapsed between first presentation of symptoms (e.g. cough, breathlessness, fatigue) and a diagnosis of ILD and also the time elapsed between first presentation of symptoms and specialist referral, and then time between specialist first referral and diagnosis/treatment. In order to contextualise our findings, we will make comparisons with patients with idiopathic pulmonary fibrosis (IPF).
In terms of exploring the possible reasons for, and consequences of, diagnostic and treatment delays, we will base our analyses on a priori knowledge and a literature search. Assuming misdiagnoses of respiratory symptoms is a significant contributory factor we will examine possible associations between prescription of bronchodilators, including inhaled corticosteroids, and the length of delays, using either linear or logistic regression models. We will use negative binomial models to estimate the rate of hospital admissions (for respiratory reasons) in patients with RA-ILD, and compare this rate with that in patents with IPF.
- ILD diagnostic and treatment delays in a cohort of patients with RA [overall delay (time between first presentation of symptoms and diagnosis), referral delay (time between first presentation of symptoms and specialist referral), and diagnostic/treatment delay (time between first specialist referral and diagnosis/treatment initiation);
- mortality (all-cause and respiratory failure);
- hospitalisation (for respiratory reasons).
Jennifer Quint - Chief Investigator - Imperial College London
Ann Morgan - Corresponding Applicant - Imperial College London
Peter George - Collaborator - Royal Brompton Hospital
HES Accident and Emergency;HES Admitted Patient Care;HES Diagnostic Imaging Dataset;HES Outpatient;ONS Death Registration Data;Practice Level Index of Multiple Deprivation