Shortening the VSP-A: preliminary development of the VSP-A12, a 12-item short-form.

The 'Vécu et Santé Perçue des Adolescents' (VSP-A) questionnaire is a French generic self-administered health-related quality of life (HRQL) instrument for adolescents which comprises 40 items, allowing the calculation of six dimensions as well as an index. Regression methods were used to select 12 items from the VSP-A to reproduce its HRQL index. The resulting 12-item short-form (VSP-A12) achieved an adjusted R2 of 0.907 in prediction of the VSP-A index. Scoring algorithm used to score this 12-item index achieved a R2 of 0.901 with the VSP-A index when cross-validated in the validation sample (n = 2941). Numerous tests of empirical validity previously published for the VSP-A were replicated for the VSP-A12, including comparisons between groups known to differ in terms of gender, age or health status. All the significant results shown by the VSP-A index were also encountered by the VSP-A12 summary measure. The ability of VSP-A12 to discriminate between healthy and ill adolescents was also proven. A test-retest correlation (4 weeks) of 0.745 was observed for the 12-item HRQL index in the target population (n = 664). Average score for this shorter index closely mirrored VSP-A index, although standard deviation was always greater for the VSP-A12.