Subcutaneous Fat Thickness and the Risk of Superficial Incisional Surgical Site Infection Following Open Appendectomy

A Chalise,M Nepal,M Shrestha,P Poudel,Subash Rai

doi:10.3126/nmcj.v23i1.36218

Abstract

Obesity is a known risk factor for surgical site infection (SSI). Recent studies have demonstrated that fat burden at the incisional site rather than body mass index (BMI) is a more precise and sensitive measure to predict the risk of SSI. The purpose of the study was to evaluate the correlation between subcutaneous fat thickness (SCFT) at the level of Mc Burney’s point and the occurrence of superficial incisional SSI among the patients undergoing open appendectomy. A total of 120 patients who underwent open appendectomy were included in the study. SCFT was measured preoperatively with ultrasonography (USG). The occurrence of superficial incisional SSI was evaluated in relation to SCFT. Previously identified well established risk factors for the development of SSI were also considered by the study. Statistical analysis was performed using SPSS version 17. Overall, superficial incisional SSI was observed in 27 (22.5%) participants. Mean SCFT at the level of Mc Burney’s point among male and female population was 2.26 cm ± 0.74 (SD) and 2.02 cm ± 0.83 (SD) respectively. Patients with superficial incisional SSI had a mean fat thickness of 2.80 cm and those without SSI had mean fat thickness of 1.97 cm. The difference in SCFT was statistically significant (p=.001). More interestingly, the area under the ROC curve was more for SCFT, in comparison to BMI among the patients who developed superficial incisional SSI (81% vs. 73%). Furthermore, we analysed the occurrence of superficial incisional SSI with SCFT cut off at 2.80 cm, which was statistically significant. As majority of the study population were young adults, risk factors like smoking, diabetes mellitus and nutritional status failed to demonstrate significant correlation with post appendectomy wound site complications. The study demonstrated that the thickness of subcutaneous fat at the site of inci sion is a good predictor of superficial incisional SSI following open appendectomy and the risk of superficial wound site infection increases as the thickness of subcutaneous fat at the site of incision increases.

Highlights

Acute appendicitis is a common differential among the patients presenting to the emergency department with acute abdominal pain and appendectomy remains one of the most commonly performed emergency procedure.[1]
The study demonstrated that the thickness of subcutaneous fat at the site of incision is a good predictor of superficial incisional surgical site infection (SSI) following open appendectomy and the risk of superficial wound site infection increases as the thickness of subcutaneous fat at the site of incision increases
Seventy eight percentage of patients had normal body mass index (BMI), as per WHO criteria[15], and none included in the study had evidence of diabetes mellitus

Summary

Introduction

The most commonly used tool to define obesity in clinical context is body mass index (BMI), a relatively nonspecific assessment of body composition, without any direct measure of adiposity.[6] Morphometric measures of body composition, in comparison, involves evaluation of certain body parameters such as subcutaneous fat thickness (SCFT), core muscle size, bone mineral density, arterial calcification, and body composition. They can directly quantify the amount of subcutaneous fat at the site of surgical wound. Morphometric measurements can be obtained by various clinical and radiological modalities.[8,9] The results of the studies comparing the accuracy and reliability of those modalities in predicting the regional burden of subcutaneous adiposity are largely heterogeneous.[10,11] We have chosen USG to measure SCFT because of its availability, reliability, and superiority over other modalities. 12, 13

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Conclusion