A validation study of the translated Stapesplasty Outcome Test 25 for measurement of disease-specific quality of life in Dutch otosclerosis patients

Introduction: otosclerosis is a common cause of acquired conductive hearing loss and can be treated using hearing aids or surgically in a procedure called stapedotomy. Surgical success rates or surgical results are usually reported using pure-tone audiometric thresholds and/or speech discrimination scores. Audiometric results and patient-reported quality of life after stapes surgery do not seem to correlate well. It is therefore our opinion that health-related quality of life measurements should be implemented as an additional outcome measure after stapes surgery. So far, there is a lack of a valid, reliable and clinically feasible measuring tool for determining health-related quality of life in Dutch patients with otosclerosis who undergo stapes surgery.

Methods and Analysis: a prospective validation study was designed to translate and validate the disease-specific Stapesplasty Outcome Test 25 (SPOT-25) in a population of Dutch otosclerosis patients who undergo stapes surgery. Seventy otosclerosis patients who will be undergoing primary stapes surgery and 50 healthy controls will be included. The otosclerosis patients will fulfill several questionnaires preoperatively, six to eight weeks postoperatively and eight to ten weeks postoperatively. The patients’ audiometric results, which are measured routinely before and after undergoing stapes surgery, will also be used. The healthy controls will fulfill the translated SPOT-25 once. Firstly, the original SPOT-25 will be translated from German to Dutch in a six-step process. Secondly, the translated SPOT-25 will be pilot-tested in a subset of patients. Lastly, validity, reliability and responsiveness of the translated SPOT-25 will be analyzed.

We expect the SPOT-25 to correlate with all three measurement instruments. We expect correlation between the change score in the “hearing function” domain of the translated SPOT-25 and the Glasgow Benefit Inventory to be higher than correlation between the translated SPOT-25 and Glasgow Health Status Questionnaire. We expect the “mental condition” and “social restrictions” domains to correlate better with the Glasgow Health Status Questionnaire than the Glasgow Benefit Inventory. Furthermore, we expect the “hearing function” domain of the SPOT-25 to correlate particularly well with mean gain in air-conduction thresholds, mean postoperative air-conduction thresholds and speech discrimination score, and less with mean gain in air-bone gap, postoperative mean air-bone gap and success defined as air-bone gap closure to 10 dB or less. We expect the other domains to correlate poorly with audiometric results.

Preoperatively, 6 to 8 weeks postoperatively and 8 to 10 weeks postoperatively in the otosclerosis patients. One measurement moment in the healthy controls.