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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.