These medical papers aim to explain the etiology, or origin, of a condition, its natural course and progression, and the range of prognoses that can result from it. These papers usually draw on a large existing evidence base about the condition, but they are also commonly drawn up soon after the emergence of a new disease to help clinicians understand what to expect with the disease. Then, as more is learned, new updated natural history studies are published. These studies are a great starting place for background and context if you’re about to cover a condition you’ve never covered before.