Appendix A. Review of Literature on Surgical Site Infections and Associated Risk Factors (continued)

Proactive Risk Assessment of Surgical Site Infection in Ambulatory Surgery Centers

Institutional Prescreening for Detection and Eradication of Methicillin-Resistant Staphylococcus aureus in Patients Undergoing Elective Orthopaedic Surgery [Kim et al (2010)]

Aims

  • Investigation performed at New England Baptist Hospital, Boston, Massachusetts
  • SSI has been identified as one of the most important preventable sources of morbidity and mortality associated with medical treatment. The purpose of the present study was to evaluate the feasibility and efficacy of an institutional prescreening program for the preoperative detection and eradication of both methicillin-resistant and methicillin-sensitive Staphylococcus aureus in patients undergoing elective orthopaedic surgery.

Methods

  • Data were collected prospectively during a single-center study. A universal prescreening program, employing rapid polymerase chain reaction analysis of nasal swabs followed by an eradication protocol of intranasal mupirocin and chlorhexidine showers for identified carriers, was implemented. Surgical site infection rates were calculated and compared with a historical control period immediately preceding the start of the screening program.

Results

  • During the study period, 7019 of 7338 patients underwent preoperative screening before elective surgery, for a successful screening rate of 95.7%. One thousand five hundred and eighty-eight (22.6%) of the patients were identified as Staphylococcus aureus carriers, and 309 (4.4%) were identified as methicillin-resistant Staphylococcus aureus carriers. A significantly higher rate of surgical site infection was observed among methicillin-resistant Staphylococcus aureus carriers (0.97%; three of 309) compared with noncarriers (0.14%; seven of 5122) (p = 0.0162). Although a higher rate of surgical site infection was also observed among methicillin-sensitive Staphylococcus aureus carriers (0.19%; three of 1588) compared with noncarriers, this difference did not achieve significance (p = 0.709). Overall, thirteen cases of surgical site infection were identified during the study period, for an institutional infection rate of 0.19%. This rate was significantly lower than that observed during the control period (0.45%; twenty-four cases of surgical site infection among 5293 patients) (p = 0.0093).

Conclusions

  • Implementation of an institution-wide prescreening program for the identification and eradication of methicillin-resistant and methicillin-sensitive Staphylococcus aureus carrier status among patients undergoing elective orthopaedic surgery is feasible and can lead to significant reductions in postoperative rates of surgical site infection.

Decolonization of orthopedic surgical team S. aureus carriers: Impact on surgical-site infections [Barbos et al. (2010)]

Aims

  • Orthopedic SSI, mostly due to S. aureus, is recognized as a major adverse event. This research aims to verify the usefulness of surgical team decolonization in order to reduce the risk of surgical-site infection.

Materials and methods

  • We performed swabs of both nares and oropharynx to identify S. aureus carriers among orthopedic team members who consented to cooperate with the study. Carriers were treated with local application of mupirocin ointment.

Results

  • Retrospective study of 1,000 consecutive patients operated before surgical team decolonization showed 6% SSIs. Of the 300 cases considered after decolonization, none developed SSI.

Conclusions

  • Though we are aware that more data need to be collected, this work might be relevant for the introduction of a new preventive protocol.

Presurgical Skin Preparation With a Novel 2% Chlorhexidine Gluconate Cloth Reduces Rates of Surgical Site Infection in Orthopaedic Surgical Patients [Eiselt (2010)]

Background

  • Postoperative surgical site infections (SSIs) are a common complication of joint surgery. Prevention depends on adequate preoperative skin antisepsis. In previous studies, use of a 2% chlorhexidine gluconate (CHG) no-rinse cloth reduced SSI rates in general surgery patients.

Methods

  • Patients admitted for a total joint procedure used a skin antisepsis protocol incorporating 2% CHG no-rinse cloths to do a site-specific wash on the night before surgery and in the holding area just before surgery.

Results

  • In the 3 quarters before implementation of the protocol, the SSI rate was 3.19%. In the 3 quarters after the 2% CHG cloth was introduced, the SSI rate decreased to 1.59%, representing a 50.16% reduction in SSIs.

Conclusions

  • The rate of SSI was cut in half after the introduction of 2% CHG no-rinse cloths in the place of a povidone-iodine (Betadine) skin antiseptic in orthopaedic patients undergoing total joint procedures. Further testing using randomization comparative protocols are required to conclude that the decreased SSI was in fact a direct result of the 2% CHG protocol.

Examples of Risk Factors Identified in the Literature for SSIs in Other Surgeries

Ploeg et al. (World J Surg, 2007) studied the risk of nosocomial infection after peripheral arterial bypass surgery.

Study design and scope

  • Single-center observational study, focusing on nosocomial infections after peripheral arterial bypass surgery, for the period Jan 1996 to Dec 2004, in a hospital in The Netherlands.

Risk factors considered

  • Patient level: age, sex, presence of diabetes, cardiovascular disease, end stage renal disease, COPD, use of steroids at admission to the hospital, current smoking status, body mass index, and American Society of Anesthesiologists (ASA) classification.
  • Procedure level (for peri and postoperative surgeries): type and indication of surgery performed, type of bypass used, total length of hospital admission, whether the surgery was performed on an emergency basis, duration of surgical procedure, blood transfusion, blood loss, the use of antibiotics perioperative and postoperative, and admission to the ICU.

Conclusions

  • A total of 607 procedures were studied, with 67 infections. SSI was the most common (55.2%), followed by urinary tract infection (16.4%) and pneumonia (14.9%) and bacteremia (10.4%). 35.1% of patients diagnosed with a SSI were diagnosed after discharge from hospital. Staphylococcus aureus was the most commonly found isolate in SSIs (48.6%) and in bacteremia (42.9%). Age, the use of corticosteroids, and critical ischemia with tissue loss were identified as risk factors for the development of a nosocomial infection. Blood transfusion was a postoperative risk factor for nosocomial infection. Nosocomial infection was associated with a prolonged hospital stay,.

Suljagić et al. (Surg Today, 2010) investigated the incidence and risk factors associated with development of SSIs in a tertiary care center.

Study design and scope

  • A prospective cohort study in a tertiary health care center in Serbia. The surveillance was initiated on general and vascular surgery patients, followed by orthopedic surgery, neurosurgery, plastic surgery and burns, cardiac surgery, thoracic surgery, urology, ear, nose, and throat surgery, and maxillofacial surgery patients.

Risk factors considered

  • Patient level: age, sex, tobacco use, body mass index, and presence of underlying diabetes mellitus.
  • Healthcare related: preoperative length of stay, length of hospital stay, preoperative showering, preoperative infection, immunosuppressive treatment, antibiotic prophylaxis, and drainage. This study also calculated an NNIS system risk index for the patients based on operation data including wound contamination class, duration of surgery, and the ASA score.

Conclusions

  • Out of a total of 5,109 surgical procedures, with an SSI rate of 6.3%. The length of hospital stay, preoperative length of stay, antibiotic prophylaxis, drainage, ASA score, class of wound contamination, and NNIS risk index were independently associated with an increased risk for SSIs. Staphylococcus aureus was the most frequently isolated microorganism, 64% of them being methicillin-resistant.

Varela et al. (Sug Endosc, 2010) compared the rate of SSIs under laparoscopic surgery over open surgery.

Study design and scope

  • A retrospective analysis of a large administrative, clinical, and financial database (University Health System Consortium) of US Academic Medical Centers and affiliated community hospitals. Study population: Adult patients going through appendectomy, cholecystectomy, antireflux, or gastric bypass from October 2004 to June 2008. Outcome: Inpatient diagnosis of SSI after laparoscopic and open surgery.

Conclusions

  • Out of 131,630 patients, the incidence of SSI was significantly lower in laparoscopic (483 of 94,665, 05%) than in open (669 of 36,965, 1.8%) surgery. Patients treated with laparoscopy were 72% less likely to experience an SSI. Hence, the conclusion is that in US academic medical centers, laparoscopy (by limiting the degree of trauma and contamination of surgical sites) significantly reduces SSI.

Finding a Method for Optimizing Risk Adjustment When Comparing Surgical-Site Infection Rates. Christian Brandt, Sonja Hansen, Dorit Sohr, Franz Daschner, Henning Rueden, Petra Gastmeier. Infection Control and Hospital Epidemiology, Vol. 25, No. 4 (April 2004), pp. 313-318.

Aims

  • During the Study on the Efficacy of Nosocomial Infection Control (SENIC) project, an index was developed that provided a better assessment of the risk of SSI than had the traditional wound classification system (6).
  • In 1991, a modification of the SENIC risk index by Culver et al.7 led to the National Nosocomial Infections Surveillance (NNIS) System risk index, which attributes points to patients if (1) their general condition, as measured by the American Society of Anesthesiologists (ASA) score, is 3 or worse; (2) the wound contamination class is contaminated or dirty–infected; or (3) an operation lasts longer than the 75th percentile of other operations of the same type.
  • The aim of this study was, using the data available from KISS, to evaluate which method was better at predicting the risk of an SSI—the basic NNIS System risk index (which assesses equally ASA score, wound class, and duration of operation) or an approach that considers the different significance of the possible risk factors, based on multiple logistic regression analyses, individually for each procedure category (and with the inclusion of age and gender as additional risk factors).

Materials and methods

  • Between January 1997 and June 2003, the Krankenhaus-Infection-Surveillance-System (KISS) gained an overview of 18 procedure categories with approximately 274,500 operations in all.
  • First, the data were stratified by variables, each divided into two levels: ASA score (1 or 2 vs 3 to 5); wound contamination class (clean or clean-contaminated vs contaminated and dirty–infected); duration of the operation (shorter vs longer than the 75th percentile of KISS operations of the same type; in contrast to the NNIS System, the cut-off point for the duration of each operation is calculated in minutes and is corrected with every new analysis); endoscopically versus non-endoscopically performed procedure, if appropriate; age (younger vs older than the 75th percentile of the patients' age distribution for each procedure category); and gender.
  • Second, the basic SSI rates were calculated using the NNIS System risk index categories. Adjacent risk index categories were compared using Fisher's exact test, with a P value of less than .05 considered significant.
  • Third, for each procedure category, various multiple logistic regression analyses were performed with stepwise variable selection (forward and backward alternately) to predict the patients' SSI outcome.

Results

  • The odds ratios for SSI in each NNIS System risk index category (compared with the risk in category 0) were obtained from logistic regression models with the NNIS System risk index categories as the sole explanatory variables (Table 3). These findings were in accordance with the SSI rates per category (Table 2).
  • An ASA score of 3 or greater was an independent risk factor for SSI in all procedures except knee prosthesis (Table 4).
  • Wound class was shown to be an independent risk factor for SSI in 6 of the 9 procedures investigated, although it was not a significant risk factor for cholecystectomy, cesarean section, or arthroscopy.
  • The predictive power of the new logistic regression models was, for most procedures, only slightly better than that of the model with NNIS System risk index categories (Table 5).

Conclusions

  • By evaluating the relative importance of each of the NNIS System risk index variables individually, we were able to confirm that the ASA score is an important component of the NNIS System risk index because it reflects the general patient condition(11)
  • A procedure lasting longer than the 75th percentile of KISS procedures of the same type was associated with a higher SSI risk for all procedures investigated except cesarean section.

Infectious Risk Factors Related to Operating Rooms. Didier Pittet, Georges Ducel. Infection Control and Hospital Epidemiology, Vol. 15, No. 7 (July 1994), pp. 456-462.

Aims

  • Most surgical infections originate from bacteria that enter the operating room at the time of operation. The causative pathogens originate from the patient's endogenous microflora, from the operating room environment, or from organisms shed by the operating room team.
  • It is estimated that 325000 postoperative wound infections occur each year in the US (3). The risk of acquiring a nosocomial infection varies according to type of procedure (4-7).
  • Risk factors related to operating rooms include patient-associated risks, the operating room environment, ventilation systems, cleansing and sterilization and operating room personnel.

Results

  • Infection rates traditionally accepted for the different types of operations are as follows: clean 1% - 5%; clean-contaminated 3% to 11%; contaminated 10% to 17% and dirty more than 17% (9)
  • Risk factors determined in a 1970 study included: recovery from abdominal operation, contaminated or dirty wound by traditional wound classification, operation lasting longer than 2 hours and patient having three or more different diagnoses at the time of discharge from the hospital.
  • The ASA score is a critical component of the risk index and attempts to account for underlying host conditions that may increase infection risk.
  • 7 measures have proven to be effective in preventing postoperative wound infections: 1 minimizing the duration of preoperative hospitalization; 2 weight reduction for obese patients; 3 eradication of remote infections; 4 hair removal just before the operation; 5 minimizing the duration of surgery' 6 appropriate use of antimicrobial prophylaxis and 7 feedback of surgical infection rates to the surgeons.
  • The causative pathogens may originate from the operating room environment, from shedding by the operating room personnel or from the patient's endogenous flora.
  • Modern standard operating rooms are virtually free of particles(including bacteria) larger than 0.5 µm when there are no people in attendance. The bacteria originate mainly from the skin of the people present in the room.
  • The number of airborne bacteria depends on the number of people present, their level of activity, and compliance with infection control practices.
  • The risk of environmentally spread infection is low in the modern, well-managed operating suite; however it depends strongly on the degree of the appropriateness of instrument and device sterilization, the efficiency of the ventilation systems, and the adequacy of cleansing of the operating theater between cases.

Conclusions

  • Air and water are suspected as the environmental source of infection, because these organisms commonly are recovered from hospital dust and can survive in soil and water.
  • The effectiveness of control programs based on surveillance with feedback of surgical infection rates to surgeons has been demonstrated in several studies (4, 6,3 8, 56, 58, 59).
  • Reporting of surgeon-specific infection rates, adjusted according to appropriate patient risk indices, constitutes a further improvement that needs to be evaluated independently regarding its efficacy as a surgical wound infection control procedure.
  • Surgical wound infection surveillance with appropriate feedback to surgeons is one of the few effective measures that helps reduce surgical infection rates, and we strongly recommend its use.

Factors Influencing the Incidence and Outcome of Infection Following Total Joint Arthroplasty. Robert Poss, Thomas S. Thornhill, Frederick C. Ewald, William H. Thomas, Nancy J Batte, Clement B. Sledge. Clinical Orthopaedics and Related Research, Issue 182, (January 1984), pp. 117-125.

Aims

  • During a 10 year period, 4240 total hip, knee and elbow arthroplasties were performed. The overall infection rate was 1.25%. Certain groups were identified as being at higher risk of infection following total joint arthroplasty: rheumatoid arthritics were 2.6 times greater risk than osteoarthritics.
  • Patients undergoing total hip arthroplasty as a revision of a previous operation were 8 times more likely to have infection than those undergoing a primary operation.
  • Patients with metal-to-metal hinged knee prostheses, when compared with patients with metal-to-plastic knew prostheses, were 20 times more likely for infection.
  • The major factors that influenced the outcome of the infected joint included the interval form the initial surgery to recognition of infection, the delay in institution of appropriate treatment, the particular joint that was infected, the integrity of the bone-cement interface, the type of prosthesis used and the host susceptibility.
  • Improvements in the surgical environment (e.g. clean-air operating rooms, prophylactic antibiotic therapy during the perioperative period, and use of ultraviolet lights) have helped reduce incidences of infection. From more than 7% to a current 1%.

Materials and methods

  • 90% of the patients who underwent total joint arthroplasty (TJA) had either rheumatoid arthritis (RA) or osteoarthritis (OA). The remaining 10% had sustained joint degeneration as a concomitant of such diseases as systemic lupus erythematosis, Gaucher's disease, ochronosis, Paget's disease and avascular necrosis.
  • The mean age of patients undergoing surgery was 65 years for osteoarthritics and 55 years for rheumatoid arthritics.
  • Patients are admitted to the hospital 48 hours prior to operation for medical evaluation, preoperative urinalysis and culture, and preoperative physical rehabilitation orientation. On the day of surgery the surgical site is shaved in the operating room immediately prior to surgical preparation. Prophylactic antibiotics are administered immediately before operation and for 48 hours after.

Results

  • There were 53 infections in 4240 procedures. The incidence of infection in each joint is shown in Table 1.
  • Primary total hip arthroplasty (THAs) were performed in 1823 patients. There were 10 infections, an incidence of 0.54%. In 189 procedures performed as a revision of a previous hip operation there were 8 infections, and incidence of 4.2%.
  • Infected patients were assigned to 1 of 2 categories: 1 infection resulting from intraoperative or perioperative contamination or seeding; 2 infection resulting from distant seeding at a later date
  • Of the 26 patients with infected joints in the perioperative infection group, 17 had the infection present within 4 weeks after operation.
  • Staphylococcus aureus in pure or mixed culture accounted for 50% of the infections.

Conclusions

  • In this study all infections occurring more than three years after operation were in patients with RA.
  • The increased risk for infection in patients undergoing revision surgery requires careful preoperative evaluation to rule out the possibility of occult infection. Because of previous surgery, large areas of dead space and scar tissue are often present. The difficulty in performing these operations results in increased operating times and increases the chance of contamination during surgery.
  • The incidence of infection in all patients undergoing TJA can be lowered further. Thorough preoperative evaluation, elimination of sites of potential bacterial seeding, and aggressive treatment of suspicious wounds should lower the number of perioperative infections.

Risk factors for surgical wound infection in HIV-positive patients undergoing surgery for orthopaedic trauma – Anani Abalo et al. Journal of Orthopaedic Surgery 18.2 (2010): 224-27.

Purpose

  • HIV-positive patients are at higher risk of perioperative infections, complications, impaired wound healing, and mortality.
  • As highly active antiretroviral therapy (HAART) is used aids is becoming a chronic, manageable condition. This means that as the life expectancy for AIDS patients rises also does the orthopedic surgeries on AIDS patients.
  • HIV-positive patients have higher rates of wound infection than do controls after internal fixation for closed fractures (24% 7 or 16% 8 vs. 5%).
  • The study reviewed records of HIV-positive patients undergoing surgery for orthopaedic trauma and identified risk factors associated with surgical wound infection.

Methods

  • Records of 29 male and 7 female HIV-positive patients aged 18 to 47 (mean, 27) year who underwent surgery for orthopaedic trauma.
  • Data on patient age, sex, dates of admission, operation and discharge, comorbidities, HIV-specific variables (HIV clinical classification, CD4+ lymphocyte count, and history of opportunistic infections), and HAART were retrieved, as were data on wound class, fracture type, surgery type, surgical wound infections, and outcomes.
  • All patients received prophylactic antibiotics, whereas 16 were on HAART.

Results

  • 8 patients had open fractures and their wounds were regarded as contaminated or dirty/infected, whereas 28 had closed fractures with clean wounds.
  • The median follow-up period was 27 months.
  • Of the 36 patients, 14 (39%) developed surgical wound infections (4 were deep and 10 superficial).
  • Only 25% of patients with closed fractures/clean wounds developed surgical wound infection.
  • 10 of the 14 surgical wound infections grew positive cultures; 80% of them were polymicrobial.
  • The most common bacterial isolates were Staphylococcus aureus, Pseudomonas spp, and Enterococcus spp.

Conclusion

  • In HIV-positive patients, rates of postoperative wound infection are higher (24 %6 and 40 %12), especially when the wounds are contaminated.
  • The CD4+ lymphocyte count is clinically relevant for stratifying the risks in HIV-infected patients.
  • Mortality and morbidity increase significantly when the category of CD4+ T-lymphocyte count is more than 2.
  • Infection rates are higher in symptomatic HIV-positive patients.
  • In HIV-positive patients, open fractures are associated with high rates of postoperative wound infection (42%7 to 72%12) and chronic osteomyelitis (50%7 to 71%16).
  • In immunocompromised patients, the capacity to resist higher bacterial loads (in open fractures or contaminated surgery) is reduced. Prophylactic antibiotics can offset but not entirely eliminate this deficiency.

Risk Infection Factors in the Total Hip Replacement - Arjona et al. European Journal of Epidemiology 13.4 (1997):443-46.

Purpose

  • Infection complications are of great importance, since they usually end with the removal of prostheses. Fortunately infection incidence has been dramatically reduced in the last years, mostly due to the administration of more effective antibiotics and to the perioperative cares, among other things.

Methods

  • The total number of patients was 873, all surgeries took place in conventional surgery theatres without ultraclean systems.
  • Prophylaxis qualification, rules and type of antibiotics employed were the following: i.v. cefazolina 2 g beginning 30 minutes before surgery plus 1 g every 8 hours during 48-72 hours after surgery.

Results

  • The patients average age was 63 years. 40% of them were males and 60% females. There were 3.43% diabetics, and there was no inmunocompromised patient.
  • Correct prophylaxis in a global percentage was of 60% and in the last year this percentage raised to 90%.
  • The percentage of wound infections constituted 6% and in the last year this figure was reduced to 1.2%.
  • The variables that presented association with infection were: incorrect prophylaxis, wrong scaring, more than one intervention, and longer than 30 days stays in the hospital.

Conclusion

  • It is interesting to establish the relationship between the fall in the number of hospital infections and the increase in the correct use of prophylaxis.

Perioperative Normothermia to Reduce the Incidence of Surgical-Wound Infection and Shorten Hospitalization – Kurz et al. New England Journal of Medicine 334.19 (1996):1209-215.

Purpose

  • Mild perioperative hypothermia (approximately 2 °C below the normal core body temperature) is common in colon surgery. It results from anesthetic-induced impairment of thermoregulation, exposure to cold, and altered distribution of body heat. Although it is rarely desired, intraoperative hypothermia is usual because few patients are actively warmed.
  • Hypothermia may increase patients' susceptibility to perioperative wound infections by causing vasoconstriction and impaired immunity.
  • Vasoconstriction decreases the partial pressure of oxygen in tissues, which lowers resistance to infection in animals.

Methods

  • The number of patients required for this trial was estimated on the basis of a preliminary study in which 80 patients undergoing elective colon surgery were randomly assigned to hypothermia (mean temperature, 34.4±0.4°C) or normothermia (involving warming with forced air and fluid to a mean temperature of 37±0.3°C).
  • The patients were selected at random, the normothermia group had temperatures maintained near 36.5°C, while the hypothermia group was allowed to have their temperature decrease to 34.5°C.
  • Core temperatures were measured at the tympanic membrane, with values recorded preoperatively, at 10-minute intervals intraoperatively, and at 20-minute intervals for 6 hours during recovery.

Results

  • One hundred four patients were assigned to the normothermia group, and 96 to the hypothermia group.
  • Intraoperative vasoconstriction was observed in 74 percent of the patients assigned to hypothermia but in only 6 percent of those assigned to normothermia.
  • Postoperative vasoconstriction was observed in 78 percent of the patients in the hypothermia group; the vasoconstriction continued throughout the six-hour recovery period. In contrast, vasoconstriction, usually short-lived, was observed in only 22 percent of the patients in the normothermia group.
  • The overall incidence of surgical-wound infection was 12 percent.
  • There were only 6 surgical-wound infections in the normothermia group, as compared with 18 in the hypothermia group.
  • The proportion of patients with wound infection was significantly higher among smokers (23 percent, or 14 of 62) than among nonsmokers (7 percent).

Conclusion

  • Perioperative hypothermia persisted for more than four hours and thus included the decisive period for establishing an infection.
  • The patients with mild perioperative hypothermia had three times as many culture-positive surgical-wound infections as the normothermic patients.
  • It is interesting to note that hospitalization was also prolonged (by about two days) in the uninfected patients in the hypothermia group.
  • Among all 200 patients in our study, those who smoked had three times more surgical-wound infections and significantly longer hospitalizations than the nonsmokers.

Factors Influencing Wound Healing After Surgery for Metastatic Disease of the Spine – McPhee et al. Spine 23.6 (1998): 726-32.

Purpose

  • To determine the risk factors for wound breakdown and infection in patients undergoing surgery for spinal metastases.
  • The life expectancy of patients with malignant tumors has generally increased because of advances in medical treatment. Metastasis to the skeleton is common and metastasis to the spine may occur frequently. Currently available rigid spinal implant devices enable extensive excision of spinal tumors.
  • Spinal fusion without instrumentation has a 1-5% risk of infection. Fusion using spinal implants may be associated with a risk of 6% or more. The rate of postoperative infection after surgery for spinal tumors is in excess of 10%.
  • Corticosteroids are useful in the management of metastatic disease and can result in remarkable palliation and useful remission.

Methods

  • Fifty-three patients underwent surgery for spinal metastases in this study.
  • The patients' records were reviewed retrospectively to determine the effect of serum concentrations of albumin and protein, blood lymphocyte count, perioperative steroid therapy, and preoperative radiotherapy on wound healing.
  • A serum albumin value less than 35 g/dL or a serum protein value less than 60 g/dL was considered to be indicative of protein depletion. A total lymphocyte count of less than 1000 cells/mm3 was considered abnormal and indicative of nutritional depletion and possible immune deficiency. Perioperative corticosteroid administration was defined as the period from 7 days before to 7 days after surgery. Perioperative radiotherapy was defined as the period 1 month before to 1 month after surgery.

Results

  • Of the 75 wounds studied, 60 healed uneventfully and 15 broke down as a result of infection or dehiscence.
  • Five wound breakdowns were associated with low serum protein values, compared with the observation of low values in only two wounds that healed primarily. Hypoproteinemia (<60 g/dL) is a risk factor for wound breakdown and infection in patients undergoing surgery for spinal metastases.
  • Five of 14 patients with wound breakdowns and 8 of 51 patients with wounds that healed primarily had abnormally low serum albumin values. An abnormally low serum albumin concentration (<35 g/dL) was a significant factor in preoperative hypoproteinemia, but alone was not a risk factor for wound breakdown.
  • Administration of perioperative steroids was associated with 11 wounds with complications and 22 wounds that healed primarily. Perioperative steroid therapy increased the risk of wound complications.

Conclusion

  • The results of this study show that nutritional factors, specifically protein depletion and, to a lesser extent, perioperative corticosteroid therapy, are significant risk factors in postoperative infection for patients undergoing reconstructive or palliative surgery for spinal metastases.
  • In general, a modest dose of properly fractionated radiation given 3 to 6 weeks before surgery or 7 to 12 days after surgery should not significantly increase surgical morbidity, whereas large doses given just before and soon after may result in increased complications.

Risk Factors for Surgical Site Infection Following Orthopedic Spinal Operations – Olsen et al. The Journal of Bone and Joint Surgery 90.1 (2008): 62-69.

Purpose

  • The most recent NNIS summary by the CDC reported a 1.25% rate of surgical site infection after laminectomy and a 2.1% rate following spinal arthrodesis.
  • We undertook a subsequent retrospective case-control study to determine if we could identify unique risk factors for surgical site infection in patients undergoing orthopedic spinal surgery.

Methods

  • The study was restricted to spine operations performed by orthopedic surgeons.
  • The charts of patients in the study were reviewed after one year for instances of SSI.

Results

  • The incidence of surgical site infection following orthopedic spinal operations was 2.0%.
  • Twenty (43%) of the forty-six infections were classified as deep incisional (involving fascia and/or muscle); eight (17%), as organ space (involving an anatomic space opened during the surgery other than the incision, and including osteomyelitis, empyema, and meningitis); and eighteen (39%), as superficial incisional (involving only skin or subcutaneous tissues).
  • All surgical site infections were treated with intravenous antibiotics in the hospital, and thirty-six (78%) of the forty-six patients had a repeat operation to treat the infection.
  • The patient-level factors that were found to be associated with a significantly increased risk of surgical site infection included diabetes, an elevated serum glucose level, a perioperative transfusion, postoperative incontinence (bowel or bladder, or both), and any incontinence (preoperative or postoperative).
  • Operations on the cervical spine, intravenous use of steroids intraoperatively, and use of cefazolin alone for infection prophylaxis were all associated with a significantly lower risk of surgical site infection.
  • Suboptimal timing of prophylactic antibiotics therapy, defined as the administration of cefazolin more than sixty minutes before the incision or any antibiotic(s) first given after the incision, was associated with an increased risk of surgical site infection.
  • Other operative variables associated with an increased risk of surgical site infection included aminoglycoside prophylaxis, irrigation of the surgical wound with an antibiotic solution (cefazolin or bacitracin), use of a drain for three or more days after the operation, and two or more surgical residents participating in the operation.
  • When the serum glucose levels were categorized according to these cutoffs, a preoperative level of >125 mg/dL was associated with a 5.3-fold increased risk of surgical site infection, and any postoperative glucose level (within five days after the operation) of >200 mg/dL was associated with a 2.9-fold increased risk of surgical site infection. Either a preoperative or any postoperative serum glucose level of >75th percentile was associated with a 4.7-fold increased risk of surgical site infection.
  • Diabetes had the strongest association with SSI, with an adjusted odds ratio of 3.5. Other variables that remained independently associated with an increased risk of surgical site infection included suboptimal timing of prophylactic antibiotic therapy (odds ratio = 3.4), an elevated serum glucose level (a preoperative random or fasting serum glucose level of >125 mg/dL or a postoperative random serum glucose level of >200 mg/dL) (odds ratio = 3.3), obesity (odds ratio = 2.2), and participation in the operation by two or more surgical residents (odds ratio = 2.2).

Proceed to Next Section

Current as of April 2013
Internet Citation: Appendix A. Review of Literature on Surgical Site Infections and Associated Risk Factors (continued): Proactive Risk Assessment of Surgical Site Infection in Ambulatory Surgery Centers. April 2013. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/stpra/stpraapa3.html