Nutritional, Physiological Factors Affect Wound Infection After Surgery for Lower-Extremity Soft Tissue Sarcoma
Key findings
- This retrospective cohort study examined the influence of nutrition, physiological factors, smoking status and BMI on the risk of wound infection in 633 adults who underwent resection of lower-extremity soft tissue sarcoma
- Both pre- and postoperative elevation in plasma glucose levels were predictive of wound infection and the need for additional surgery; postoperative levels were more predictive than preoperative levels
- Lower albumin and lower score on the Prognostic Nutritional Index (PNI) were also associated with poorer outcomes
- Being a current or former smoker was associated with wound infection (OR, 1.64; P=0.002) and additional surgery (OR, 1.55; P=0.02)
- A sliding glucose scale and control of glucose in the first 48 hours after surgery are crucial to optimize wound healing; past/current smokers and patients with preoperative albumin <3.5 g/dL should be monitored closely postoperatively
Soft tissue sarcoma (STS) in the lower extremity is associated with better survival than STS at other sites, but surgery can produce deep, complex wounds that often require soft tissue reconstruction or amputation. The risk of wound infection increases with certain oncologic risk factors (e.g., tumor size and stage) and treatment-related factors (e.g., radiation, grafting and incision width).
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Kevin Raskin, MD, acting chief of Orthopaedic Oncology at Massachusetts General Hospital, Joseph H. Schwab MD, chief of the Orthopaedic Spine Center, and director of Spine Oncology and co-director of the Stephan L. Harris Chordoma Center at Mass General Cancer Center, Santiago Lozano-Calderon, MD, PhD, orthopaedic oncology surgeon, and musculoskeletal oncology fellows at Mass General conducted the first comprehensive study of patients' nutritional status before and after resection of STS of the lower extremity.
In Annals of Surgical Oncology, they report that current smokers and patients with low preoperative albumin, preoperative malnutrition or elevated postoperative glucose were at increased risk of delayed wound healing and wound infection.
Study Methods
The researchers retrospectively studied 633 adults treated for sarcoma of the lower extremity at Mass General between January 1992 and December 2017 who had a postoperative wound check within one month of the procedure. The median age was 52 (range, 18–97). Follow-up visit notes were checked until the wound fully healed or a complication occurred.
120 patients developed wound infections (33 mild, 15 moderate and 72 severe) and 89 required additional surgery.
Plasma Glucose
Elevated glucose was significantly associated with wound infection and the need for additional surgery. For every 5 mg/dL increase:
Preoperative Glucose
- Infection—adjusted OR (aOR), 1.07 (P<0.001)
- Additional surgery—aOR, 1.04 (P=0.03)
Postoperative Glucose
- Infection—aOR, 1.13 (P<0.001)
- Additional surgery—aOR, 1.10 (P<0.001)
On receiver operating curve (ROC) analysis, postoperative glucose remained an effective predictor of wound infections (area under the curve (AUC), 0.77) and additional procedures (AUC, 0.70). Preoperative glucose was not as predictive (AUC<0.7).
Pre- and postoperative serum glucose were risk factors for all severities of infection.
Albumin and Nutrition
The team had records of preoperative serum albumin levels for 309 patients, and for 252 patients, they were able to calculate the Prognostic Nutritional Index (PNI) score: 10 × serum albumin (g/dL) + (0.005 × total lymphocyte count). The normal value is >50.
Lower albumin and lower PNI were both significantly associated with wound infection and the need for additional surgery. However, AUCs were between 0.60 and 0.70. Based on sensitivity and specificity analysis of the ROC curve, 3.5 g/dL serum albumin was determined to be the optimal cutoff value.
Other Physiological Variables
Pre- and postoperative partial thromboplastin time, prothrombin time/international normalized ratio, white blood cell count, preoperative platelet count and hemoglobin were not tied to wound healing.
Smoking Status and BMI
- Current or previous smoking was associated with wound infection (OR, 1.64; P=0.002) and additional surgery (OR, 1.55; P=0.02)
- There was no significant difference between the average body mass index of patients with normal wound healing versus those with wound complications
Clinical Pearls
- A sliding glucose scale and control of glucose in the first 48 hours after surgery are crucial to reducing the risk of wound infections
- Patients with preoperative albumin <3.5 g/dL should be monitored closely after surgery—and the likelihood of complications increases with decreasing values
- Dietary counseling and/or renal interventions may be beneficial to mitigate the risk of postoperative complications related to hypoalbuminemia
- Clinicians should take a smoking history before surgery, provide access to smoking cessation counseling if warranted and closely monitor past and present smokers postoperatively
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