Characteristics of infectious spondylitis patients with normal white blood cell count and C-reactive protein level and associated factors

Little is known about infectious spondylitis with normal inflammatory markers. We investigated the characteristics of patients having infectious spondylitis with normal white blood cell (WBC) count and normal C-reactive protein (CRP) level at the time of diagnosis. This study was conducted at three university-affiliated hospitals in Korea. The medical records of patients aged ≥ 15 years diagnosed with infectious spondylitis between 2003 and 2020 were reviewed. Multivariable logistic regression was performed to identify factors associated with normal WBC and CRP level. 740 patients were included, and 34 patients had normal WBC and CRP level. Multivariable analysis revealed that tuberculous spondylitis (adjusted odds ratio [aOR], 3.65; 95% confidence interval [CI], 1.77–7.51; P < 0.001) and cervical spine involvement (aOR, 3.10; 95% CI, 1.09–7.67; P = 0.02) are associated with normal WBC and CRP level. Approximately 5% of patients with infectious spondylitis have normal WBC and CRP level. Even if these inflammatory markers are normal, diagnostic tests including tissue cultures are necessary in clinically suspected cases.