The Use And Impact Of Antimicrobial Prophylaxis In Neurosurgery At Kenyatta National Hospital, And The Economic Impact Of Treatment Of Neurosurgical Site Infections.

Abstract

Background Neurosurgical site infections are associated with high morbidity and mortality and increased hospitalisation costs. There is paucity of data on the incidence, impact and cost of neurosurgical site infections among trauma patients with contaminated to dirty wounds in East Africa. There are no systematic reviews and meta-analyses evaluating antimicrobial prophylaxis in neurosurgery in the region. Objectives The objectives of the study were to generate and appraise quality of evidence for antimicrobial prophylaxis, measure the prevalence and incidence of surgical site infections among trauma patients and identify independent patient and surgical risk factors for development of surgical site infection. The study also set out to evaluate the effectiveness of antimicrobial prophylaxis, identify the patterns of antimicrobial use and medication errors and evaluated the cost of treating neurosurgical site infections. Methods The study was conducted between September 2013 and January 2016 at the Kenyatta National Hospital Neurosurgical unit. Adult neuro-trauma patients with contaminated to dirty wounds were recruited. A systematic review and meta-analysis were carried out to evaluate the quality of evidence for antimicrobial prophylaxis. A cross sectional study was conducted to identify patient and procedure related risk factors for infection. A cohort study was conducted to determine the incidence of surgical site infections, efficacy of antimicrobial prophylaxis and patterns of xxiii antibiotic use. A cost of illness study was carried out to determine the impact of surgical site infections on patient expenditure. Descriptive and inferential data analysis was done using STATA version 13 software. Approval to carry out the study was obtained from the Kenyatta National Hospital- University of Nairobi Research and Ethics Committee. Results Moderate quality evidence supported the use of systemic antimicrobial prophylaxis. For the cross sectional study, the prevalence of surgical site infections was high, at 21%. The commonest causes of trauma were assault (40%) and road traffic accidents (34%). There was a statistically significant association between the cause of trauma and development of infection (p=0.004). The independent risk factor for development of surgical site infections was trauma due to assault (OR 0.27; 95% CI 0.07, 1.02) and this was statistically significant (p=0.054). From the cohort study, craniotomy was the most common surgical procedure performed (56.5%, n=39). Only 26.1% (n=18) patients received antibiotics for prophylaxis, with ceftriaxone being the most commonly used (78%, n=14). The incidence of surgical site infection was 37.7% (n=26). Presence of an epidural haematoma was an independent risk factor for development of infection (OR 7.368, 95% CI 1.396, 38.894). Craniotomy and evacuation of haematoma procedures, when done on the same patient, were protective for patients with epidural haematomas. Following effect measure modification, antimicrobial prophylaxis was only effective in patients who had undergone both craniotomy and evacuation of haematomas (OR 0.50, 95% CI 0.18, 1.38). Unexpectedly, the effectiveness of prophylaxis also increased with an xxiv increase in the number of surgical procedures and the duration of surgical procedures for those who underwent craniotomy. Several medication errors were noted: overdoses, unspecified dose, route and frequency of administration for all antibiotics, prolonged duration of antibiotic use, inappropriate choice and combinations of antibiotics, inappropriate doses, and an unclear distinction between prophylaxis and treatment of infection. The total expenditure on all health commodities was higher in patients with infection than those without infection. The key cost drivers were expenditures on meropenem, phenytoin, urea, electrolyte and creatinine tests and CT scans. Conclusion Systemic antimicrobial prophylaxis is effective in preventing neurosurgical site infections. Use of antimicrobial impregnated shunts is too expensive. The incidence of infection among trauma patients with contaminated to dirty wounds is high. Antimicrobial prophylaxis effectiveness increases when craniotomy and evacuation of haematomas are done on the same patient. Irrational antibiotic use has no impact on the rates of surgical site infection. Neurosurgical site infections increase treatment costs of neurosurgical trauma patients.