In the first decades of the 20th century, patients at lung sanatoria all over Sweden formed clubs that organised mutual support and arranged social events. By the late 1930s, they banded together in a national organisation, which quickly became a respected and influential actor in the health and social policy landscape. However, the decline of tuberculosis became a major threat to the continued relevance of this otherwise flourishing organisation. In this paper, we show how tuberculosis became a basis for political mobilisation, and how the organisation managed to survive through a targeted effort to assemble people with cardiovascular disease as a new group to organise. This sheds light on the transformation of disease concepts in the epidemiological transition, and demonstrates how patient mobilisation played a key role in reshaping them.