Development and validation of QoL5 for clinical databases. A short, global and generic questionnaire based on an integrated theory of the quality of life.

OBJECTIVE To develop and validate a short, global, and generic quality of life (QoL) questionnaire for clinical databases. The construct validity and item weighting of existing questionnaires are increasingly questioned. DESIGN Cross-sectional population study. SUBJECT 2460 Danes aged 18-88 years, randomly selected through the Danish Central Person Registry. INTERVENTIONS Ten questions covering the spectrum of the integrative theory of QoL together with the Nottingham Health Profile (NHP), Sickness Impact Profile (SIP), and self-estimated QoL questionnaire were sent by mail. A test-retest study of 50 people was conducted after one month. MAIN OUTCOME MEASURES Construct and criterion validity, reliability, and sensitivity. RESULTS QoL5 correlations with SIP, NHP, Self-estimated QoL were 0.37, 0.52, and 0.76, respectively, and increased among those who were unwell. Cronbach's alpha was 0.69. All correlations in Siegel's test were over 0.6, and the test-retest correlation was 0.82. Only 12 respondents in each group will be needed to detect a difference of 10% in the QoL score between two groups. CONCLUSIONS QoL5 is a valid global and generic QoL measurement. Despite the use of only five questions, internal consistency and sensitivity were acceptable. So a relevant and practical outcome measurement is available for clinical databases.