Objective: The goal of the work described here was to develop and validate a measure of the impact of epilepsy on an adolescent's quality of life that is based on direct exploration of the adolescent's views.
Methods: Initial scale development was based on data generated through qualitative methods (focus groups) in a previous study [McEwan MJ, Espie CA, Metcalfe J, Brodie MJ, Wilson MT. Seizure 2004;13:15-31]. A draft measure was piloted (n=30) and refined using correlational methods. Psychometric properties were established by means of a preliminary field trial (n=78).
Results: An initial item pool of 76 was refined to 50. The structure of the measure mirrored the conceptual model derived from focus group study; Part 1 covered issues relating to adolescent development (identity formation) with five subscales, and Part 2 covered epilepsy-related issues with four subscales. The final GEOS-YP had good internal consistency (alpha=0.91) and test-retest reliability (rho=0.75). Concurrent and construct validity was acceptable, and the GEOS-YP discriminated on dimensions of clinical importance. Participant feedback suggested the measure has excellent face validity and potential clinical utility.
Conclusions: The GEOS-YP is a direct measure of how adolescents perceive epilepsy impacts their quality of life. The GEOS-YP has sound psychometric properties and provides a relatively brief and potentially useful clinical outcome tool.