Incidence of Infectious Complications Following Cochlear Implantation in Children and Adults

Abstract

This cohort study uses data from state health care databases to determine the incidence and timing of infectious complications following cochlear implant surgery among patients in 5 US states between 2006 and 2016.

Cochlear implantation is the treatment of choice for patients with severe to profound sensorineural hearing loss.¹ Infection following cochlear implantation can result in hearing loss secondary to implant removal and, rarely, meningitis.² Published rates of infection after cochlear implantation vary widely (1.4%-8.2%),^3,4 and there is a paucity of generalizable, large-scale data regarding the risks of infection after implantation. This study aimed to determine the incidence and timing of infectious complications following cochlear implantation.

Methods

A retrospective cohort study was conducted using the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases, State Emergency Department Databases, and State Ambulatory Surgery Databases⁵ from Florida, Maryland, New York, Vermont, and Wisconsin. States were chosen with longitudinal, encrypted personal identifiers to link patient visits. We included patients 1 year and older with an International Classification of Diseases, Ninth Revision or International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-9/10) or Current Procedural Terminology, Fourth Edition procedure code for cochlear implantation in the State Inpatient Databases or State Ambulatory Surgery Databases from January 1, 2006, to September 30, 2016. Infectious complications were defined as ICD-9/10 diagnosis codes after implantation for meningitis, petrositis, mastoiditis, prosthetic inflammation/infection, labyrinthitis, postauricular fistula, scalp cellulitis, or site-specific wound complications plus a Staphylococcus or general incision and drainage code. Additionally, ICD-9/10 diagnosis codes within 180 days of implantation for postoperative infection, unspecified cellulitis, or general wound complications plus a Staphylococcus or general incision and drainage code were included as infectious complications. Codes for infectious complications within 2 weeks of each other were considered a single complication. Complications were evaluated separately in children and adults.

Complication rates were calculated per 1000 person-years with 95% confidence intervals, and mean cumulative functions were generated accounting for recurrent infections. Per HCUP standards, events with fewer than 11 cases were not reported to preserve patient anonymity. All statistical analyses were performed in SAS version 9.3 (SAS Institute Inc). This study was exempted from review by the Washington University School of Medicine institutional review board.

Results

In total, 1975 children and 5474 adults received cochlear implants. Of the children, 51% were boys, with a median age at implantation of 4 years (interquartile range [IQR], 2-8 years) and median follow-up of 5.3 years (IQR, 2.5-8.0 years). Infectious complications occurred in 64 children (3.2%) at a rate of 8.2 complications per 1000 person-years (95% CI, 6.6-10.2). Children aged 1 and 2 years had the highest rates of infectious complications, 15.4 and 14.8 complications per 1000 person-years, respectively (Figure 1).

Figure 1. Incidence of Infectious Complications by Age Group.

Error bars indicate 95% confidence intervals. Inset figure presents incidence rates by age for children aged 1 to 3 years.

Among the adults, 53% were women, the median age at implantation was 63 years (IQR, 48-75 years), and the median follow-up time was 4.3 years (IQR, 2.0-7.3 years). Infectious complications occurred in 110 adults (2.0%) at a rate of 5.2 complications per 1000 person-years (95% CI, 4.3-6.1). Adults 65 years and older did not have a higher rate of complications than younger adults.

Fifty-five percent (n = 47/86) of pediatric complications occurred within 180 days of implantation, compared with 43% (n = 56/131) of adult complications (Figure 2). Of the 64 children with infectious complications, 22% (n = 14) developed recurrent infectious complications, while 14% (n = 15) of the 110 adults with infectious complications developed recurrent infections. Prosthetic inflammation/infection (n = 86 [40%]) was the most common infectious complication, followed by mastoiditis (n = 56 [26%]) and cellulitis (n = 32 [15%]). Fewer than 11 cases of meningitis were observed.

Figure 2. Mean Cumulative Incidence of Infectious Complications in Pediatric and Adult Cochlear Implant Recipients.

The difference in incidence rates of infectious complications between the pediatric and the adult cohort is most pronounced in the first 180 days after implantation (blue area).

Discussion

The low rates of infectious complications in cochlear implant recipients in this study support the safety of cochlear implants and are useful as reliable point estimates for future investigations. Meningitis was exceedingly rare.

Young children aged 1 and 2 years experienced infectious complications more frequently than older children. However, the benefits of early implantation on language development are well established,⁶ and the low absolute risk for infection does not outweigh these substantial benefits.

The overall increase in infectious complications in children was predominantly driven by repeat and early complications, occurring within 180 days. Increased vigilance by physicians is warranted when caring for young children early after implantation and children with prior implant infections.

Limitations of this study include poor sensitivity for nonsurgical, outpatient complications and no studies validating the ICD-9/10 codes defining infectious complications.

Section Editor: Jody W. Zylke, MD, Deputy Editor.