The context of the WHO's definition of health led to a widened understanding of the traditional health term as well as to a broadened spectrum of possible criteria for therapeutical success. Health-related quality of life, i.e. the patient's subjective state of health, has since come explicitly into the focus of medicine. Health-related quality of life stands for the individually perceived state of health. It is a dynamical construct that changes with time, as adaptation processes have to be taken into consideration which severely diseased patients go through in the course of their disease. These are reflected as changes in the assessment of their subjective health condition. Beside a delineation of the construct, actual research and its embedding in the medical context, the following article is elucidating the methodical procedure as well as some basic assumptions in quality of life research.
Subsequently, a selection of both generic and disease-specific instruments is presented that are used in the national and international field of research. The outlook will give a comparison of the different methods of dealing with response-shift processes as an essential challenge in present quality of life research.