Validation of an outcomes instrument for tonsil and adenoid disease

OBJECTIVE: To design and validate a disease-specific health status instrument-the Tonsil and Adenoid Health Status Instrument-for use in children with tonsil and adenoid disease. DESIGN: Prospective psychometric and clinimetric instrument validation in 3 stages. SETTINGS: A tertiary academic pediatric specialty hospital and a tertiary academic hospital, in 2 different cities. PATIENTS/OTHER PARTICIPANTS: Children with tonsil and adenoid disease presenting for evaluation and treatment (n = 224). INTERVENTION/METHOD: Prospective instrument validation. Stage 1 consisted of initial item testing, reduction, and subscale construction; stage 2, reliability and validity testing, factor analysis, and final item reduction; and stage 3, responsiveness analysis. MAIN OUTCOME MEASURES: Test-retest and internal consistency reliability; content, construct, and criterion validity; orthogonal principal components factor analysis; and response sensitivity analysis. RESULTS: Factor analysis and item analysis confirmed 6 distinct subscales measuring different constructs (aspects) of disease-specific health status that are affected by tonsil and adenoid disease: eating and swallowing, airway and breathing, infections, health care utilization, cost of care, and behavior. For each subscale, the Tonsil and Adenoid Health Status Instrument demonstrated excellent test-retest reliability (r = 0.72-0.88) and internal consistency reliability (Cronbach alpha = .73-.87). Content validity was ensured during the design process. Construct validity was demonstrated by means of convergent and divergent validity with a global quality-of-life instrument (the Child Health Questionnaire, version PF28). Criterion validity was also satisfactory. Finally, the instrument was appropriately sensitive, with high standardized response means and effect sizes. CONCLUSIONS: The Tonsil and Adenoid Health Status Instrument is a valid, reliable, and sensitive instrument with 6 distinct subscales. This instrument has significant utility for outcomes research in children with tonsil and adenoid disease.