Factors predicting the duration required to control infection in pyogenic spondylitis: A retrospective observational study

Background: Treatment for pyogenic spondylitis tends to be prolonged in controlling the infection; however, few reports have examined the factors associated with the duration required to control infection. We analyzed a consecutive cohort of patients who underwent surgery for pyogenic spondylitis to identify predictors associated with the duration required to control infection in pyogenic spondylitis. Methods: This was a retrospective observational study. We investigated 60 patients who underwent surgery for pyogenic spondylitis in the Department of Orthopedic Surgery at Tokyo Medical and Dental University Hospital in Japan. We evaluated the significance of various factors on predicting the duration required to control infection in pyogenic spondylitis using univariate and multivariate Cox regression analysis. Results: Univariate Cox regression analysis showed that body mass index, blood urea nitrogen, C-reactive protein (CRP), modified Glasgow prognostic score, CRP-albumin ratio, neutrophil-to-lymphocyte ratio, Kulowski classification, magnetic resonance imaging stage, number of infected vertebral bodies, and psoas abscess were significantly associated with the duration required to control infection. Multivariate Cox regression analysis showed that a longer duration from the first visit to the operation, higher CRP levels, and more infected vertebral bodies were independent factors associated with the duration required to control an infection. The cutoff value for CRP in predicting prolonged control of infection was 7.87 and the number of vertebrae was 3. Conclusions: We found that a long duration from the first visit to the operation, a high CRP level, and multiple infected vertebral bodies were significantly associated with the longer duration required to control an infection in pyogenic spondylitis. These findings could help in identifying patients who pose a higher risk of requiring a prolonged period to control the infection in pyogenic spondylitis.