Pericarditis diagnosis in the CPRD: a potential early indicator of undetected cancer and marker of subsequent increased cancer risk

Date of ISAC Approval: 
08/12/2016
Lay Summary: 
Pericarditis is a condition with inflammation of the pericardial sac, which surrounds the heart. Most cases of pericarditis are thought to be caused by infections (viral or bacterial), but the condition can also occur after a heart attack, or in the presence of autoimmune diseases or cancer. In some published case reports, patients admitted to hospital with pericarditis have been found to have undetected cancer. The increased risk of pericarditis related to cancer, may stem from direct growth of cancer cells from nearby structures or spread of cancer cells through the blood stream. Our aim is to use data from the UK Clinical Practice Research Datalink (CPRD), which is a large database containing anonymised general practice records, to find out how often pericarditis may be the first manifestation of undetected cancer. If pericarditis is frequently a first manifestation of cancer, such a finding could have implications about screening for cancer among patients who have developed pericarditis.
Technical Summary: 
Pericarditis is a condition with inflammation of the pericardial sac surrounding the heart. Most cases of pericarditis are thought to be caused by infections (viral or bacterial), but the condition can also occur after a heart attack, or in the presence of autoimmune diseases or cancer. In some published case reports, patients admitted to hospital with pericarditis have been found to have undetected cancer. The increased risk of pericarditis related to cancer, may stem from direct growth of cancer cells from nearby structures or spread of cancer cells through the blood stream. Our aim is to investigate whether pericarditis may the first manifestation of some undetected cancers. We will do this by conducting a matched cohort study using primary care data from the Clinical Practice Research Datalink (CPRD); people presenting with pericarditis will be compared with similar people without pericarditis, and followed up for cancer. Cox proportional hazards models will be fitted to quantify the associoation between pericarditis and cancer outcomes. If pericarditis is frequently a first manifestation of cancer, such a finding could have implications about screening for cancer among patients who have developed pericarditis.
Health Outcomes to be Measured: 
The outcomes of interest will be first occurrence of cancer. We will restrict our analysis to include the cancers with sufficient power to detect a potential association (colon, pancreas, lung, malignant melanoma, breast, prostate, bladder, non-Hodgkin lymphoma, leukaemia, and any cancer combined; see Section G above). The primary outcomes for hypothesis testing will be lung cancer, breast cancer, non-Hodgkin's lymphoma, leukaemia, and "any cancer" (combined). This is because we have stronger reason to expect a priori an increased risk of these cancers in people with acute pericarditis, based on increases in risk seen in previously published data.7,8 The secondary outcomes will the remaining site-specific cancers, namely bladder, colon, pancreas, prostate cancers, and malignant melanoma. We have observed increased risks for all of these but malignant melanoma in a companion study using Danish national registry data (as yet unpublished, revised manuscript under review with Circulation). In the CPRD, cancers will be identified through medical codes from the CPRD medical dictionary related to cancer, which have been mapped to ICD-10 chapter 2 headings for a previous study.
Collaborators: 

Dr Krishnan Bhaskaran - Chief Investigator - London School Of Hygiene & Tropical Medicine (LSHTM)
Kirstine Kobberoe Sogaard - Collaborator - Aarhus University Hospital
Dr Krishnan Bhaskaran - Corresponding Applicant - London School Of Hygiene & Tropical Medicine (LSHTM)
Professor Liam Smeeth - Collaborator - London School Of Hygiene & Tropical Medicine (LSHTM)

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