Development and validation of the Zurich chronic middle ear inventory (ZCMEI-21): an electronic questionnaire for assessing quality of life in patients with chronic otitis media

Because existing patient-reported outcome measures (PROMs) specific for chronic otitis media (COM) are lacking certain relevant symptoms and dimensions of health-related quality of life (HRQoL), we aimed to develop and validate a new questionnaire for comprehensively measuring HRQoL in adult patients with COM. An expert panel and patients were involved in developing the first version of the Zurich chronic middle ear inventory, containing 33 items (ZCMEI-33). An electronic application was chosen not only to provide maximal data quality, but also to facilitate and accelerate data analysis. Item reduction was performed by testing the questionnaire in a first cohort (n = 85). Using sequential statistical analysis, the ZCMEI-33 was reduced to 21 items (ZCMEI-21). Subsequently, the ZCMEI-21 was validated in a second cohort (n = 76). Validation revealed a Cronbach's alpha of 0.91, indicating excellent internal consistency. Moreover, the ZCMEI-21 was able to discriminate between patients with COM and healthy participants (p < 0.0001), thus possessing good discrimination validity. Assessing criterion validity, the ZCMEI-21 total score was compared to a question directly addressing HRQoL and the EQ-5D descriptive system score, a generic measure of HRQoL. Whereas the ZCMEI-21 total score and the EQ-5D descriptive system score were only moderately correlated (r = 0.60, p < 0.0001), the ZCMEI-21 total score and the question directly addressing HRQoL showed a strong correlation (r = 0.74, p < 0.0001). In conclusion, sufficient information on reliability and validity was obtained to propagate the application of the ZCMEI-21 to quantify HRQoL in patients with COM.