A statistical term used as a benchmark in clinical studies. Quality of life quantifies quality of life, measured by means of standardized questionnaires, which are often designed specifically for the disease and intervention.
Quality of life cannot be measured (absolutely), but differences between (therapy) groups in quality of life can. Therefore, it is usually only useful in randomised, large studies. The results depend strongly on the type of survey. The problem of missing values in the surveys and the problem that patients with (increasingly) poorer quality of life answer the surveys less is unsolved.