Why Are Pre-existing Conditions Important in Epidemiology?

Pre-existing conditions significantly influence the morbidity and mortality rates associated with new diseases. They can exacerbate the severity of new illnesses and complicate treatment options. For instance, patients with pre-existing cardiovascular diseases are more likely to experience severe complications from respiratory infections like the flu or COVID-19. Epidemiologists must account for these conditions when designing studies, interpreting data, and implementing public health interventions.