The value of preoperative labs in identifying “at-risk” patients for developing surgical site infections after pediatric neuromuscular spine deformity surgery.

January 13, 2020

STUDY DESIGN:

This is a retrospective cohort study via a single surgeon, two-hospital database.

OBJECTIVE:

PSF in NMS patients is a high-risk surgery, with rates of SSI up to 24%. There is conflicting evidence in the literature regarding a possible association between low preoperative nutritional lab values and heightened risk of SSI after PSF. A retrospective analysis of a 20-year cohort of 111 pediatric neuromuscular scoliosis (NMS) patients that underwent posterior spinal fusion (PSF) with instrumentation was performed. Overall, seven patients (6.3%) developed a postoperative surgical site infection (SSI). With the possible exception of transferrin, low preoperative lab values (prealbumin, Hgb/Hct, WBC, TLC, total protein, albumin) were not associated with SSI. These findings question the utility of the current methodology of preoperative laboratory evaluation in identifying patients at elevated risk for SSI following PSF.

METHODS:

A single-surgeon, two-hospital database was reviewed to identify all patients who underwent PSF for NMS. Diagnoses included cerebral palsy (n = 82), myelomeningocele (n = 13), spinal muscular atrophy (n = 4), and other (n = 12). Medical records for 117 patients were examined; 6 were excluded due to missing lab values. SSI was defined as an infection necessitating a return to the operating room for irrigation and debridement of the surgical site. Demographic information, preoperative lab values, spinal deformity magnitude, and surgical procedure data were recorded.

RESULTS:

There were 50 males and 61 females with a mean age of 14 years and 2.5 months (8-20 years). Seven patients (6.3%) experienced postoperative SSI. SSI rate for PSF to pelvis was 7.7% vs. PSF to lumbar spine, 3.0% (NS; p = 0.672). Length of PSF was not statistically associated with SSI (p = 0.172). SSI due to gram positives and polymicrobial gram negatives occurred with equal incidence. Preoperative lab values of transferrin, prealbumin, albumin, WBC count, total lymphocyte count, and total protein were not associated with SSI. Patients with postoperative SSI had higher mean Hct compared to controls (p = 0.041). While 40.6% of controls had low Hgb (< 13.8 g/dl), all patients who developed SSI had Hgb within the normal range (p = 0.043). Similarly, while 37.6% of controls had low Hct (< 40.7%), all patients who developed SSI had Hct within the normal range (p = 0.05).

CONCLUSION:

Low preoperative nutritional labs, Hgb/Hct, and TLC values were not found to be associated with an increased incidence of SSI in this analysis. These findings question the utility of preoperative lab values in identifying “at-risk” populations for SSI after PSF for NMS.