Comparison of Hospital Cost and Resource Use Associated With Antibiotic-Impregnated Versus Standard Shunt Catheters

Abstract

S ince their introduction in the 1950s, cerebrospinal fluid (CSF) shunts have been the mainstay of hydrocephalus treatment. Despite improvements in preoperative and perioperative antibiotic therapy, 5% to 15% of all shunts placed in North America become infected. The clinical consequence of shunt infections in both pediatric and adult high-risk populations has been described extensively and includes reduced intelligence quotient, psychomotor retardation, and seizures. Several independent risk factors have been identified, including patient age, cause of hydrocephalus, duration of surgery, revision surgery, surgeon experience, preceding shunt infection, postoperative CSF leakage, and conversion from external ventricular drain to shunt. The direct medical cost of shunt infection has been reported to be $17 300 to $48 454, with an estimated total annual cost of $100 million. Antibiotic-impregnated shunts (AISs) were recently introduced with the aim of reducing the incidence rate of shunt-related infections. The AIS catheters release antibiotics over the course of several weeks to prevent the colonization of shunt systems by Gram-positive bacteria, which accounts for the preponderance of shunt infections. To date, the majority of published studies on this subject have demonstrated a statistically significant reduction in shunt-associated infections when AIS catheters were used; however, there has been some reluctance to adopt these systems because of their increased cost compared with conventional catheters. Furthermore, the efficacy of AIS catheters in these studies was confined to the pediatric population. Less evidence exists supporting their utility in adult hydrocephalus. We recently reported a significant reduction in the incidence of shunt infection in adult hydrocephalus after the categorical conversion to AIS catheters at our institution. In the present study, we performed a retrospective cohort study and economic analysis to determine whether the use of AIS catheters in adult hydrocephalus at our institution has been cost-effective. METHODS All adult patients undergoing CSF shunt insertion by a single surgeon (D.R.) over a 7-year period at the Johns Hopkins Hospital were retrospectively reviewed (2004-2009). In 2006, a categorical switch to AIS catheters (Bactiseal, Codman) was made. Before 2006, standard nonimpregnated shunt catheters were used. In 2006 and thereafter, AIS catheters were used in all cases regardless of patient characteristics. Once the 250th consecutive AIS shunt system was implanted in February 2009, this retrospective cohort study was initiated to determine the incidence of infection in our experience with AIS catheters. As a comparison group, the 250 consecutive patients receiving standard non-AIS CSF shunts immediately before the AIS conversion were reviewed (2004-2006). Patient demographics, CSF shunt surgery history, clinical presentation, radiological studies, operative variables, shunt type and configuration, and CSF, blood, and hardware culture data were reviewed. Only adult patients (. 21 years of age) were included. The majority of patients undergoing CSF shunting for adult hydrocephalus in our practice were treated for normalpressure hydrocephalus (NPH) or idiopathic intracranial hypertension (pseudotumor cerebri). As previously described in detail, NPH patients were shunted if they demonstrated cognitive decline, gait abnormalities, or urinary incontinence with significant improvement after trial CSF drainage. As also previously described by our group, pseudotumor cerebri patients were shunted if they had medically refractory headache or visual decline and persistently elevated opening pressures on serial lumbar punctures. Throughout the reviewed period of time (2004-2009), no modifications were made to the shunt surgery technique or procedure other than the use of AIS catheters in 2006. All procedures were done in the same surgical suites by the senior author. Moreover, the treatment of shunt infection remained standardized throughout the reviewed period. Shunt infection was defined as a clinical suspicion of shunt infection (fever, increased white blood cell count, and/or wound breakdown involving the shunt) with positive cultures Copyright 2011 by The Congress of Neurological Surgeons 0148-396X