Infectious Complications Related to Intrathecal Drug Delivery System and Spinal Cord Stimulator System Implantations at a Comprehensive Cancer Pain Center

Background: Intrathecal drug delivery (IDD) and spinal cord stimulator (SCS) systems are implantabledevices for the management of both chronic and cancer pain. Although these therapies have favorablelong-term outcomes, they are associated with occasional complications including infection. Theincidence of infectious complications varies from 2 - 8% and frequently requires prolonged antibioticsand device revision or removal. Cancer patients are particularly susceptible to infectious complicationsbecause they are immunocompromised, malnourished, and receiving cytotoxic cancer-related therapies.Objective: Determine if cancer pain patients have a higher incidence of infectious complicationsfollowing implantation of IDD or SCS systems than non-cancer pain patients.Study Design: Retrospective chart review.Setting: Single tertiary comprehensive cancer hospital.Methods: Following local Institutional Review Board (IRB) approval, we collected data oninfectious complications for IDD and SCS systems implanted at MD Anderson Cancer Centerfor the treatment of cancer and chronic pain. The examined implants were performed from July15, 2006, to July 14, 2009. In addition, we obtained data regarding patient comorbidities andperioperative risk factors to assess their impact on infectious complications.Results: One hundred forty-two devices were implanted in 131 patients during the examined period.Eighty-three of the devices were IDD systems and 59 were SCS systems. Eighty percent of the patientshad a diagnosis of cancer. Four infectious complications were noted with an overall infectious risk of2.8%. The infection rate was 2.4% for IDD systems versus 3.4% for SCS systems (P = 1). All infectionswere at the implantable pulse generator (IPG) or pump pocket site. The rate of infection was 2.7% forcancer patients and 3.3% for non-cancer patients (P = 1). Neither the perioperative administration ofprophylactic antibiotics (P = 0.4) nor the National Nosocomial Infection Surveillance (NNIS) risk levelfor individual patients (P = 0.15) were statistically associated with infectious complication. The meansurgical time was longer for cases with infection at 215 ± 93 minutes versus 132 ± 52 minutes for thosewithout infection which was statistically significant (P = 0.02).Limitations: The major limitation of this study is that it was a retrospective analysis. An additionallimitation is that 51(38.9%) of our patients either died or were lost to follow-up during the yearfollowing implantation which may have led to an underestimation of our infection rates.Conclusions: The experience of this tertiary cancer pain center demonstrates that infectiouscomplications following implantation of IDD and SCS systems are relatively rare events in cancerpatients. Contrary to our initial hypothesis, no difference was found in the infection rate betweencancer and non-cancer patients. The main factor associated with increased risk of infectiouscomplications was increased surgical time, indicating a need to minimize patient time in theoperating room. The low infectious complication rate seen in this series compared to previousreports in non-cancer patients is likely multifactorial in nature.Key Words: Spinal cord stimulation, intrathecal drug delivery, implantable pain therapies,neuromodulation, pain procedures, pain, complications, infection, surgical site infection