In this study the reliability and validity of generic and disease-specific questionnaires has been assessed focusing on responsiveness.
This is part of a study on the effects of recurrent acute otitis media (rAOM) on functional health status (FHS) and health-related
quality of life (HRQoL) in 383 children with rAOM participating in a randomized clinical trial. The following generic questionnaires
were studied: 1. RAND general health rating index, 2. Functional Status Questionnaire (FSQ Generic and FSQ Specific), 3. TNO-AZL
Infant Quality of Life (TAIQOL), and the following disease-specific questionnaires: 1. Otitis Media-6 (OM-6), 2. Numerical
rating scales (NRS) for child and caregiver (NRS Child and NRS Caregiver), and 3. a new Family Functioning Questionnaire (FFQ).
Reliability was good to excellent (Cronbach’s α range 0.80–0.90, intraclass correlation coefficient range 0.76–0.93). Moderate
to strong correlations were found between the questionnaires as well as between questionnaires and relevant clinical indicators
(
r = 0.29–0.49), demonstrating construct validity. Discriminant validity for children with few versus frequent episodes of acute
otitis media per year was good for most questionnaires (
P < 0.004) but poor for the otitis media-related subscales of the TAIQOL (
P = 0.10–0.97) and both NRS (
P = 0.22 and 0.48). Except for the TAIQOL subscales, change scores were significant (
P < 0.003) for generic and disease-specific questionnaires. Effect sizes were somewhat higher for disease-specific compared
to generic questionnaires (0.55–0.95 versus 0.32–0.60) except for the TAIQOL subscales, which showed very poor sensitivity
to change. Anchor-based methods resulted in a somewhat larger range of estimates of MCID than distribution-based methods.
Combining distribution-based and anchor-based methods resulted in similar ranges for the minimally clinical important differences
for generic and disease-specific questionnaires: 2–15 points on a 0–100 scale. Apart from the generic TAIQOL subscales, both
generic and disease-specific questionnaires used in this study showed good psychometric qualities and responsiveness for use
in clinical studies on children with rAOM.
Keywords Childhood infection - Acute otitis media - Functional health status - Quality of life - Reliability - Validity - Responsiveness