The WHO-Five Well-being Index (WHO-5) was derived from a larger rating scale developed for a WHO project on quality of life in patients suffering from diabetes [
7]. During the first psychometric evaluation 10 of the original 28 items were selected due to the homogeneity they had shown across the various European countries participating in this study [
7]. Because positive psychological well-being has to include positively worded items only, these 10 items were then reduced to five items (WHO-5) which still covered positive mood, vitality and general interest. The five items are: (a) being in good spirits, (b) feeling relaxed (c) having energy (d) waking up fresh and rested, (e) being interested in things. Each of the five items is rated on a 6-point Likert scale from 0 (= not present) to 5 (= constantly present). The theoretical raw score ranges from 0 to 25. Thus, higher scores mean better well-being. The raw score is obtained by adding the figures in the boxes. A score below 13 indicates poor well-being and is an indication for testing for depression, as is the case if the patient has answered 0 to 1 on any of the five items [
3]. In order to monitor possible changes in well-being, the percentage score is used. The percentage value is calculated by multiplying the score by 4 and thus obtaining a scale from 0 (worst imaginable well-being) to 100 (best imaginable well-being). Conventionally > 50 is interpreted as indicating no depression, 30 – 50 mild depression and < 30 moderate depression. A 10% difference indicates a significant change [
8]. Appendix 1 contains the full version of the items. The six items of the BDI-6 index were derived from the original version of Beck’s Depression Inventory BDI-21 in a clinical validation study [
6], using experienced psychiatrists as index of validity, to capture major depressive disorder (MDD) in a brief format. In this process, 12 items were shown to follow the global severity index of the experienced psychiatrists. However, many of these 12 items had local dependency. Hence, the BDI items 1 (sadness), 2 (pessimism) and 4 (lack of satisfaction) showed a very high local dependency. Moreover, item 5 (guilt), item 3 (sense of failure) and item 6 (sense of punishment) also had a very high local dependency. On the other hand, the selected items in the BDI-6 have a high clinical correspondence to MDD, without being related to each other. The BDI-6 has not yet been tested or validated in a child psychiatric population. The six items are: (1) feelings of sadness, (5) feelings of guilt, (11) being irritable, (13) having decision problems, (15) ability to work and (17) feeling tired. When this study was designed, the BDI-II had not yet been validated for the Swedish version, while BDI-A1 was in use. The six BDI-6 items were retroactively extracted from the full 21-item BDI-A1 version. The BDI-6, as used in this study, thus contains six items on a 4-point scale yielding a total score by summation of the individual items of 0–18 p (0 p means no depression and 18 p maximum depression score). The conventional cut-off scores for BDI-6 are < 6 no depression, 6–7 mild depression, 7 moderate depression. Appendix 2 contains the full version of the items.