Prevalence is the proportion or total number of cases of a disease or condition that exist in a defined population at a specific point in time (point prevalence) or over a defined period (period prevalence). It reflects how widespread a condition is in a community.
Prevalence is distinct from incidence, which measures the rate of new cases arising over time. A condition with a high prevalence may have a relatively low incidence if people live with it for many years (such as hypertension or atrial fibrillation). Conversely, a condition with high incidence but low survival will have lower prevalence.
In the context of sudden cardiac arrest and related conditions, prevalence data helps identify how many people in the UK are living with conditions that place them at risk. For example, hypertrophic cardiomyopathy has a prevalence of around 1 in 500 in the general population. Heart failure affects around 900,000 people in the UK, and atrial fibrillation affects around 1.4 million. Understanding prevalence informs healthcare planning, resource allocation, and decisions about which conditions warrant population screening.
Survivorship data also uses prevalence thinking: the number of people in the UK living with the consequences of cardiac arrest (including cognitive, psychological, and physical sequelae) is growing as survival rates slowly improve. This makes post-arrest support services, cardiac rehabilitation, and survivorship clinics increasingly important.
« Back to Glossary Index