Objective: Surgical site infection (SSI) is a well-documented cause of patient morbidity, with an associated increase in cost to the healthcare system. The move to outpatient surgery is to reduce the overall cost of surgery in conjunction with improved patient morbidity.
The authors aim to determine the incidence of SSIs in the outpatient setting and associated risk factors. This information will prove to be invaluable to overall patient care.
Methods: The databases of 2205 spinal procedures performed over 10 years by a single surgeon were reviewed. Two groups created; Group 1 patients with procedures performed in the hospital setting and Group 2 patients with procedures performed in the ambulatory surgery centre. Excluded cases were patients under 18 years old, acute trauma and minor orthopaedic procedures. Included cases were cervical fusions, disc replacement and lumbar decompressions with or without fusion. Outcomes assessed included; age, body mass index (BMI), surgeon time and estimated blood loss (EBL). Relative risk factors such as BMI, smoking, alcohol use and a number of spinal levels operated on were also assessed as independent risk factors for SSIs.
Results: There were1010 included cases, 642 in a hospital setting and 368 in an outpatient setting. Mean age and BMI were 53 ± 0.5 years and 28.3 ± 0.3 kg/m2, respectively, with no intergroup significance. Surgical times of 217 ± 11 minutes and 117 ± 8 minutes and EBL of 323 ± 33 mL lost and 73 ± 8 mL demonstrated significance (p = 0.001) between the hospital and outpatient group. The overall incidence of SSIs was 1.6% and there was a significant intergroup difference, p = 0.045. Obesity and multilevel surgeries proved to be significant independent risk factors, p = 0.005 and p = 0.01, respectively. Smoking had the highest relative risk 10.9 and was also significant, p = 0.02.
Conclusion: Incidence rate of SSIs in this study showed a significant difference between inpatient and outpatient setting. Modifiable risk factors such as weight, smoking, alcohol use and numbers of levels necessary for operation should be considered. This will impact preoperative patient selection, the procedure required and allow for a decrease in SSI risk.