The evolution of concepts regarding arterial hypertension in the first half of the 20th century

In the first half of the 20th century, arterial hypertension evolved from a discrete measurable indicator into a distinct clinical and statistical category. Concepts of essential, secondary, benign, and malignant hypertension gradually took shape, though the boundaries between these categories remained fluid. This phase culminated in the sixth revision of the International Classification of Diseases, adopted in 1948: hypertensive disease was assigned a separate block of codes, distinguishing between essential benign, essential malignant, and renovascular forms. Thus, its inclusion in the classification was not the beginning, but rather the culmination of a long transition from the observation of a symptom to a standardized nosology.