Validation of the German language version of the Chronic Ear Survey and its psychometric comparison with an established German measurement instrument

Background: With the Chronic Ear Survey (CES), a validated measurement instrument for the assessment of disease-specific health-related quality of life (HRQoL) has been available internationally since 2000. The aim of this study was to provide a validated German version of this international instrument and to compare it with the German Chronic Otitis Media Outcome Test 15 (COMOT-15). Methodology: The CES was translated into German via a forward-backward translation process. For validation, 79 patients with COM undergoing middle ear surgery were prospectively included. HRQoL was determined preoperatively and 6 months postoperatively using the CES and the COMOT-15. Pure tone audiometry was also performed at both measurement time points. In the control examination, an additional retrospective assessment of the preoperative situation was additionally performed using the CES and the COMOT-15 to assess the response shift. The determined psychometric characteristics were internal consistency, test-retest reliability, discrimination validity, agreement validity, responsiveness, and response shift for both measurement instruments. Convergent validity of both measurement instruments was assessed using linear regression. Results: On the basis of the CES, patients with COM could be reliably distinguished from patients with healthy ears. The CES showed satisfactory reliability with high internal consistency (Cronbach a 0.65-0.85) and high retest reliability (r>0.8). The global assessment of HRQoL impairment correlated very well with the scores of the CES (r = 0.51). In addition, it showed a high sensitivity to change (standardized response mean -0.86). Compared to the COMOT-15, it showed a lower response shift (effect size -0.17 vs. 0.44). Both measurement instruments correlated only slightly with air conduction hearing threshold (r = 0.29 and r = 0.24, respectively). The concordant validity of both measurement instruments was high (r= 0.68). Conclusion: The German version of the CES shows satisfactory psychometric characteristics, so that its use can be recommended. The CES focuses on the influence of ear symptoms on HRQoL, whereas the COMOT-15 also includes functional and psychological aspects. Due to only minor response shift effects, the CES is particularly suitable for studies with multiple repeat measurements.