“…In eight of these studies, we found argument for measuring QOL or health-related QOL, referring to SF-36 as the most valid and widely applied tool [27,35,46,53,54,61,75,76]. In six of the papers [4,28,33,36,46,57], QOL or health-related QOL was defined as a multidimensional concept with subjective elements which was hard to assess and use as outcome in clinical trials. Furthermore, these papers also emphasised the importance and difficulties in working with the concept.…”