The effects of spondylodiscitis on the inflammation burden in infective endocarditis

Background: This study investigates the effects of spondylodiscitis on the inflammation burden in infective endocarditis patients. Methods: A prospective, observational study was conducted between September 2018 and October 2022 in a non-surgical teaching hospital. Patients with a definite or possible and treated as infective endocarditis were recruited from the Alkmaar Endocarditis Team meetings. Spondylodiscitis was diagnosed based on symptoms and radiological findings. The inflammation burden was defined as the area under the C‑reactive protein (CRP) curve. Results: 174 consecutive patients with infective endocarditis were included (mean age 73 years, 34.5% female). Concomitant spondylodiscitis was present in 32 patients (18%), frequently associated with Streptococcus species (38%). At admission, the mean level of CRP was significantly higher in patients with concomitant spondylodiscitis (p = 0.004). The median CRP area under the curve was significantly higher in spondylodiscitis patients (4.2 × 10⁶ min.mg/l [1.2 × 10⁵ − 1.6 × 10⁷ min.mg/l] vs 2.0 × 10⁶ min.mg/l [8.7 × 10⁴ − 1.6 × 10⁷ min.mg/l], p < 0.001). This difference remained during the whole treatment period. At 6 months of follow-up, rates of mortality and relapse of infective endocarditis were not significantly different. Conclusion: The prevalence of spondylodiscitis in non-referred patients with infective endocarditis was 18%. Endocarditis patients with spondylodiscitis had an increased inflammation burden at and during admission. This difference in normalisation of CRP levels was particularly apparent in the final phase of antibiotic treatment but not related to infectious complications. Despite an augmented inflammation burden, spondylodiscitis was not associated with mortality, cardiac surgery or infectious relapse.