A Retrospective Cohort Study on the Influence of Comorbidity on Soft Tissue Reactions, Revision Surgery, and Implant Loss in Bone-anchored Hearing Implants.

OBJECTIVE: To identify risk factors for complications after bone-anchored hearing implant (BAHI) surgery. STUDY
DESIGN: Retrospective cohort study.
SETTING: Tertiary referral center. PATIENTS: All adult patients who received titanium bone-anchored hearing implants at our clinic between September 1, 1988 and December 31, 2007 were approached to fill out a questionnaire on comorbidity factors. A total of 581 patients with 669 implants were included in the analysis. MAIN OUTCOME MEASURES: Implant loss, soft tissue reactions, and revision surgery after BAHI implantation.
RESULTS: Skin disease and profound learning difficulties were risk factors for time to first soft tissue reaction, hazard rate ratio of 3.41 (95% CI 1.45-8.01) and 3.42 (1.03-11.39), respectively. Female gender showed a trend toward a negative risk for time to first soft tissue reaction, hazard rate ratio 0.60 (0.35-1.03). In multivariable analysis, skin disease and female gender were observed as independent associative factors, adjusted hazard ratio 3.08 (1.32-7.16) and 0.56 (0.33-0.94). For revision surgery, female gender and cardiovascular disease were identified as negative risk factors in univariable analysis, and smoking showed a trend toward a negative risk, with hazard ratios of 0.15 (0.07-0.32), 0.07 (0.03-0.20), and 0.51 (0.24-1.07), respectively. In multivariable analysis, smoking and female gender were observed as independent associative factors, adjusted hazard ratio 0.45 (0.22-0.95) and 0.14 (0.06-0.30). Smoking could be identified as a risk factor for implant loss with a hazard ratio of 3.32 (1.36-8.09).
CONCLUSION: Retrospective analysis of comorbidity factors and clinical outcomes revealed risk factors for postoperative complications after BAHI surgery.