Influenza (flu) is a common respiratory infection causing over 40,000 people to be admitted to hospital in the UK every year. Most patients survive infection and are discharged from hospital after a stay of 9 days. Research into other respiratory infections: pneumonia and COVID-19, show a greater risk of having a stroke or a heart attack after infection. It has been noted that at times of flu epidemics there is an increase in deaths from heart disease and strokes. Small studies have shown a potential increased risk of developing diabetes after flu.
The frequency at which heart disease, stroke and diabetes occurs after being hospitalised with flu is yet to be studied. It is unclear who is at risk of these complications and how long post initial infection they are at risk. We propose using the data from the Clinical Practice Research Datalink linked to Hospital Episode Statistics to determine the:
• frequency of consultation following hospitalisation with influenza and the reasons why.
• risk of having a heart attack or stroke after being hospitalised with influenza
• risk of the developing diabetes post hospitalisation with influenza or pneumonia.
• period post hospitalisation with Influenza that contains the greatest risk of developing the above diseases
We will investigate what diseases are more likely to develop after hospitalisation with flu and pneumonia, who develops these complications and when do they develop. The findings of this research will help us discover ways to improve the care of patients recovering from respiratory viruses.
Objectives
• To determine the frequency and reason for consultation after hospitalisation with influenza.
• To determine the incidence of cardiovascular and metabolic events following hospitalisation with influenza and the length of risk period.
• To determine the incidence of diabetes after admission with pneumonia.
Methods
Adults with a first episode of hospitalised influenza between 2004-2023 as recorded in CPRD linked
to HES based on ICD-10 codes (J09-J11.8) will be included. When investigating the incidence of diabetes post pneumonia, adults with a first episode of hospitalised pneumonia between 2004-2023 as recorded in CPRD linked to HES based on ICD-10 codes (J12-J18.9) will be included. HES linked data will be used to determine hospitalisations and attendances to A&E and ONS death registration data will be used to determine deaths. Data will be collected on basic patient demographics, pre-existing comorbidities, consultations after discharge and development of comorbidities. There will be 2 control groups: non-hospitalised cohort matched for age, gender, and GP practice and a cohort hospitalised for sepsis between 2004-2023 as recorded in CPRD linked to HES.
Data analysis
Statistical analyses will be performed using ‘R’. Analysis will be split into pre-COVID (2004-2019), COVID (2020-2022), post-COVID (2022-2023) to investigate the effect of COVID-19 influenza or pneumonia presentations to hospital. Development of MI, stroke and diabetes post influenza and diabetes post pneumonia will be described as incidence rate and incidence rate ratios with 95% confidence intervals. We will use a series of Cox regression models to determine whether hospitalisation with influenza gives you a higher risk of developing an acute MI, stroke or diabetes, adjusting for potential confounders. Subanalysis will be performed to investigate the risk of new onset cardiovascular or cerebrovascular disease.
The findings of this research will us identify ways to improve the care of patients recovering from influenza and pneumonia.
1. The nature of healthcare consultations following hospitalisation with influenza
Hospitalisation for Influenza; readmission to hospital; Consultation with GP; reason for hospital, A&E or GP visit.
2. Cardiovascular and cerebrovascular events after hospitalisation with influenza
a. The risk of cardiovascular disease after hospitalisation with influenza
Hospitalisation for Influenza; NSEMI; STEMI; unstable angina; angina; heart failure
b. The risk of cerebrovascular disease after hospitalisation with influenza
Hospitalisation for Influenza; stroke; TIA
3. The incidence of diabetes post hospitalisation with influenza
Hospitalisation for Influenza: Type-1 diabetes; Type-2 diabetes; Prediabetes; hyperglycaemia.
4. The incidence of diabetes post hospitalisation with pneumonia
Hospitalisation for pneumonia; Type-1 diabetes; Type-2 diabetes; Prediabetes; hyperglycaemia
Tricia McKeever - Chief Investigator - University of Nottingham
Sophie Middleton - Corresponding Applicant - University of Nottingham
Charlotte Bolton - Collaborator - University of Nottingham
Yue Huang - Collaborator - University of Nottingham
HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation