The definition of disability was based on self-reported questions about ADL and mobility limitations included in the face-to-face questionnaire in the four BHIS. For mobility limitations, the question “What is the furthest you can walk on your own without stopping and without severe discomfort?” was analysed, with possible answers: “a. Only a few steps”, “b. More than few steps, but less than 200 m”, or “c. 200 m or more”.