Risk factors for delayed infections after spinal fusion and instrumentation in patients with scoliosis

There are limited published data about the risk factors for the development of delayed infections after spinal fusion and instrumentation in the population with scoliosis. The objective of this study was to evaluate the predictive factors of development of delayed infections in patients with scoliosis who underwent surgical treatment. A total of 17 patients with scoliosis and delayed infections were identified from 3463 patients with scoliosis who received surgical treatment. The control group was composed of 85 patients with scoliosis without infections, matched for sex, age, approximate date of surgery, and diagnosis. These 2 groups were compared for demographic distribution and clinical data to investigate the predictive factors of delayed infections. The overall incidence rate of delayed infections was 0.49%. The variables of age, body mass index, and number of levels fused were similar between the 2 groups. The average primary curve magnitude for the delayed infection and control (uninfected) groups was 80.4° ± 27.0° (range 47°-135°) and 66.3° ± 11.6° (range 42°-95°), respectively (p = 0.001). Operation time in the group with delayed infections was 384.7 ± 115.9 minutes versus 254.4 ± 79.2 minutes in the control group (p = 0.000), and estimated blood loss was 1342.2 ± 707.2 ml versus 833.9 ± 235.6 ml (p = 0.000) in these 2 groups, respectively. The perioperative mean red blood cell transfusion requirement in the delayed infection group was significantly higher than that found in patients without infections (2.8 ± 2.3 units/patient versus 1.1 ± 1.6 units/patient, respectively; p = 0.000). Logistic regression analysis showed that operation time and allogenic blood transfusion were the 2 independent predictors of delayed infections (odds ratio [OR] 1.021, 95% confidence interval [CI] 1.010-1.033, and OR 1.546, 95% CI 1.048-2.278, respectively). The occurrence of a delayed infection in patients with scoliosis who undergo surgical treatment is most likely multifactorial and is related to surgical time and the use of allogenic blood transfusion.