Quality of Life Research, 8

Presentation at the ISOQOL Conference, Barcelona, November 1999.

Background: The 22‑item Well‑being Questionnaire (Bradley, 1994), measuring Depression, Anxiety, Energy and Positive Well‑being, has been translated into 20+ languages, including most European languages.  The factor structure of the W‑BQ22 often shows overlap of Anxiety and Depression subscales, and very high reliability coefficients indicate redundancy.  Development work on a Japanese translation (Riazi et al, 1999) suggested a 12‑item version (W‑BQ12) would improve the structure and eliminate redundancy, and this was confirmed with a Dutch translation (Pouwer et al, 1998).  Both W‑BQ versions were evaluated in a recent multinational clinical trial in English (UK, S.Africa, USA), French (France, Switzerland), German (Germany, Austria, Switzerland), Dutch, Danish, Norwegian, Swedish (Sweden, Finland) and Finnish.

Method: 2,282 patients (44% in USA) with insulin-treated diabetes (Type 1 and Type 2), participating in Phase 2 and Phase 3 multinational randomised-controlled trials of a new longer-acting insulin, provided data for psychometric analyses on the 8 translations.

Results:  As expected, factor analyses of the W‑BQ22 showed an unclear structure with Depression and Anxiety subscales overlapping.  W‑BQ22 loadings were driven as much by negative vs. positive wording of the items as by the particular aspect of well-being.  Whole-scale reliabilities for the W‑BQ22 in this study were very high, suggesting some redundancy (alpha = 0.88 to 0.92).  The W‑BQ12 results showed the expected clear 3-factor structure (Positive Well-being, Negative Well-being and Energy) in English, French, German, Danish, Norwegian and Swedish.  Dutch has already been confirmed with a larger sample.  Finnish requires further evaluation with a larger sample.  Reliabilities for the W‑BQ12 varied from alpha = 0.81 to 0.86 (all languages).  Significant differences found using the W‑BQ22 were also found with the W‑BQ12.

Conclusions:  Validity and reliability of the W‑BQ12 are confirmed for all countries except Switzerland and Finland, in English, French, German, Danish, Norwegian and Swedish, plus Dutch.  Preliminary evidence suggests the W‑BQ12 is at least as sensitive to change as the W‑BQ22.