Response-shift bias and parent-reported quality of life in children with otitis media

Objectives: To validate the 6-item quality-of-life survey (OM-6) and to investigate response-shift bias regarding children with otitis media. Setting: Otorhinolaryngology department of a university hospital that serves the southernmost part of the Netherlands. Patients: Seventy-seven children (age range, 12-38 months) experiencing persistent otitis media with effusion and scheduled for placement of tympanostomy tubes. Survey: The OM-6 measures health-related quality of life in 6 domains: physical suffering, hearing loss, speech impairment, emotional distress, activity limitations, and caregiver concerns. Intervention: Parents completed the OM-6 before surgery (pretest) and 6 weeks after surgery (posttest). At the posttest, parents also completed a retrospective version of the pretest (retrospective pretest). Results: For most items, the test-retest reliability was good (R > 0.8). The internal consistency of the OM-6 was satisfactory (alpha = .79). The construct validity, determined by correlating the ear-related global quality-of-life measure and the OM-6 summary score, was fair (R = -0.77, P < .01). Prospective change in quality of life on the OM-6 ranged from moderate (standardized response mean greater than or equal to 0.5) to large (standardized response mean greater than or equal to 0.8). Response-shift bias was present at the group level (t = -3.3, P < .01). Retrospective change was significant for hearing loss (z = -3.3, P < .05) and ear-related global quality of life (z = -3.6, P < .05). Conclusions: The validity of the OM-6 has been proved in a Dutch population. The data suggest that parents underestimate the seriousness of hearing loss and overestimate the quality of life of their child before surgery, indicating a response shift. Treatment results could lead parents to realize that the situation before surgery had been worse than they thought.