Background
Sarcoidosis is a rare inflammatory condition where clusters of cells called granulomas develop at different sites of the body. The disease course is unpredictable and can range from a self-limiting to severe organ involvement and death.
Why study sarcoidosis
Despite the severity of sarcoidosis, it’s astonishing how little we know about condition in the UK. We do not know the total number of people with the disease or how many new diagnoses are made each year. Studies from other countries demonstrate difference by region and ethnicity, but we are unaware if the same patterns are seen in the UK. Death from sarcoidosis is largely attributable to lung and heart complications, and older studies suggest an that the mortality rate is increasing. We do not know if this trend has plateaued or continues along a similar trajectory.
Objective
Using CPRD with linked hospital and mortality data, our objective is to calculate the number of patients with sarcoidosis (prevalence) and the number of new diagnoses each year (incidence) in the United Kingdom. We will describe this data by ethnicity and across regions. We will examine the severity of disease by calculating the rates of hospitalisation, organ damage and death, and examining factors that predict these outcomes.
Potential impact
Bridging important knowledge gaps will ultimately improve outcomes for affected individuals. Clinicians will be armed with insight into the condition, enhancing accurate diagnosis and improving navigation of treatment options. Understanding regional variations will improve NHS resource allocation and access to vital clinical trials.
Technical Summary (Max. 300 words)
Background:
Sarcoidosis is a rare systemic inflammatory disorder of unknown aetiology, which can result in organ damage and premature death. Despite its clinical significance, there is a scarcity of UK data on disease incidence, prevalence, and regional variation. Studies conducted decades ago indicated a rising mortality rate. There are no recent data on this, and the status of this trajectory is uncertain.
Objective:
To determine the incidence, prevalence, morbidity, and mortality rates of sarcoidosis in the United Kingdom.
Methods:
The study population of interest is patients with primary or secondary care diagnoses of sarcoidosis between 2003 and 2023. Incidence and prevalence rates will be calculated by year, and stratified by age group, sex, ethnicity, and region. The mortality rates for sarcoidosis with be calculated using linkage with UK Office for National Statistics death register, and age-adjusted Standardised Mortality Ratios will be estimated by indirect standardisation according to UK mortality data. Through linkage with the NHS Digital Hospital Episode Statistics datasets, rates of all-cause hospitalisation, and hospitalisation with sarcoidosis as a primary diagnosis, will be calculated by person years. Rate ratios of hospitalisation and death will be estimated using a matched non-sarcoidosis comparator cohort, and regression models will be used to examine risk factors for severe disease outcomes. Disease severity will be analysed by calculating rates of organ-specific damage and examining the use of immunomodulating therapy.
Public health benefits:
This will be the first study to describe the epidemiology of sarcoidosis in the United Kingdom. Establishing the burden of disease and characterising high-risk populations will enable the development of targeted interventions for facilitating early diagnosis. Understanding the morbidity and mortality associated with sarcoidosis is crucial for refining healthcare policies, optimizing resource allocation and improving patient outcomes.
Primary outcome; Incidence and prevalence rates of sarcoidosis
Key secondary outcomes: 1) all-cause 1-year mortality; 2) all cause and sarcoidosis-specific hospitalisation rate; 3) incidence of disease-specific damage; 4) incidence and time to prescription of immunomodulating therapy.
Katie Bechman - Chief Investigator - King's College London (KCL)
James Galloway - Corresponding Applicant - King's College London (KCL)
Mark Russell - Collaborator - King's College London (KCL)
Martin Gulliford - Collaborator - King's College London (KCL)
HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation