Safety profiles of bone-conduction hearing implants revisited: A meta-analytic comparison adjusted for follow-up time.

purposeTo estimate incidence rates of adverse events associated with bone-conduction hearing implants from primary literature and to compare rates among different technological designs.

methodsA systematic literature review and meta-regression was conducted to estimate incidence rates of minor and major complications and their consequences (i.e., revision surgery, explantation, re-implantation and becoming a non-user) while testing for effects of device design, age group, mean follow-up time and study type. These four designs of bone-conduction systems were included: 1) active transcutaneous with electromagnetic transducer (aBCIem), 2) active transcutaneous with piezoelectric transducer (aBCIpz), 3) passive transcutaneous (tBAHA), and 4) passive percutaneous (pBAHA).

resultsThe final dataset included 170 articles reporting on 6451 implantations and 1847 minor and 668 major events. Mean follow-up time was a significant predictor of incidence rates (p < 0.001), with lower rates reported in studies with longer follow-up times. After adjusting to the median follow-up time, the pooled incidence rate of minor complications was significantly lower in aBCIem (p < 0.05) compared to other designs. For both major events and revision surgery, pooled incidence rates were significantly higher in pBAHA compared to aBCIem (p < 0.001) and tBAHA (p < 0.001), but not compared to aBCIpz (Major: p = 0.197; Revision: p = 0.248). Becoming a non-user occurred significantly more frequently in tBAHA compared to other designs (p < 0.005). No statistically significant differences were found in rates of explantation and explantation with re-implantation.

conclusionWhen comparing across multiple studies, adverse event rates should be adjusted for different lengths of follow-up. Synthesizing published evidence without considering follow-up time may lead to false conclusions.