The Cambridge Otology Quality of Life Questionnaire: an otology-specific patient-recorded outcome measure. A paper describing the instrument design and a report of preliminary reliability and validity

Objective: The Cambridge Otology Quality of Life Questionnaire (COQOL) is a patient-recorded outcome measurement (PROM) designed to quantify the quality of life of patients attending otology clinics. Design: Item-reduction model. A systematically designed long-form version (74 items) was tested with patient focus groups before being presented to adult otology patients (n. 137). Preliminary item analysis tested reliability, reducing the COQOL to 24 questions. This was then presented in conjunction with the SF-36 (V1) questionnaire to a total of 203 patients. Subsequently, these were re-presented at T + 3 months, and patients recorded whether they felt their condition had improved, deteriorated or remained the same. Non-responders were contacted by post. A correlation between COQOL scores and patient perception of change was examined to analyse content validity. Setting: Teaching hospital and university psychology department. Participants: Adult patients attending otology clinics with a wide range of otological conditions. Main outcome measurements: Item reliability measured by item–total correlation, internal consistency and test–retest reliability. Validity measured by correlation between COQOL scores and patient-reported symptom change. Results: Reliability: the COQOL showed excellent internal consistency at both initial presentation (α = 0.90) and 3 months later (α = 0.93). Validity: One-way analysis of variance showed a significant difference between groups reporting change and those reporting no change in quality of life (F(2, 80) = 5.866, P < 0.01). Conclusions: The COQOL is the first otology-specific PROM. Initial studies demonstrate excellent reliability and encouraging preliminary criterion validity: further studies will allow a deeper validation of the instrument