Clinical Observations in Patients With Cystic Fibrosis–Related Diabetes and Self-Reported Ototoxicity Symptoms

Abstract

Purpose: Persons with cystic fibrosis (PwCF) are at high risk for ototoxicity due to the routine use of intravenous aminoglycoside (IV-AG) antibiotics in respiratory infection management. Additionally, factors that contribute to ototoxicity-related symptom development and severity in PwCF are unknown. Given the increased risk of ototoxicity in people with diabetes, we explored the association between cystic fibrosis–related diabetes (CFRD) and self-reported ototoxicity symptoms (tinnitus and vestibular problems) in PwCF treated with aminoglycosides. Method: PwCF ( N = 39; 25 females, 14 males; M age = 30.1 years, SD = 10.3) were recruited from the Cystic Fibrosis Care Center at Oregon Health & Science University. Patients completed the validated questionnaires to ascertain their experiences with ototoxicity-related symptoms of tinnitus and balance function. The diagnosis of CFRD, including oral glucose tolerance testing (OGTT), insulin treatment, hemoglobin A1c, and cumulative IV-AG treatment history, was obtained through a medical chart review. Participants were classified into three groups based on their medical diagnoses via OGTT: normal glucose tolerance (NGT; control; n = 16), abnormal glucose tolerance (AGT; n = 9), and CFRD ( n = 14). Participants in each group were further classified based on survey outcomes for ototoxicity-related symptoms. Results: There was a trend toward a higher proportion of patients with CFRD reporting tinnitus compared to the AGT and NGT groups, but did not meet statistical significance ( X 2 = 2.24, p = .13). Approximately, 43% of patients with CFRD reported experiencing clinically significant tinnitus lasting > 3 min compared to 11% in the AGT group and 13% in the NGT group ( X 2 = 3.751, p = .05). Cumulative IV-AG exposure tended to be higher in CFRD compared to other groups. High balance function was generally reported in all groups. Conclusions: Patients with CFRD have greater ototoxicity-related symptoms. Further investigation of the relationship between CF-related comorbidities and the risk of developing ototoxicity-related symptoms is warranted to improve the detection and management of ototoxicity in PwCF.