Systemic inflammatory markers differentiate between orbital cellulitis and non-specific orbital inflammation

Abstract

ABSTRACT Purpose Bacterial orbital cellulitis (OC) and diffuse non-specific orbital inflammation (DNSOI) may be challenging to differentiate clinically. This study investigates the utility of systemic inflammatory markers, namely white cell count (WCC) and C-reactive protein (CRP), in differentiating between OC and DNSOI. Methods A single-centre retrospective study of patients diagnosed with OC or DNSOI, between 2003 to 2021, who had WCC and/or CRP obtained at presentation. The mean levels of these factors and the proportion of positivity were compared between OC and DNSOI. A receiver operating characteristic (ROC) analysis was conducted to calculate the specificity and sensitivity of WCC or CRP in each group. Results 49 patients were included in this study. The mean age was 56 ± 20 years, and 21 patients were females. 26 (53.1%) patients had OC, and 23 (46.9%) patients had DNSOI. Mean WCC for OC and DNSOI were 14.5 × 103/μL and 9.27 × 103/μL, respectively (P = 0.001). Mean CRP for OC and DNSOI were 104.4 mg/L and 10.0 mg/L, respectively (P < 0.001). The optimal CRP cut-off value of 20.2 mg/L demonstrated 90.9% sensitivity and 90.5% specificity (AUC = 0.946, P < 0.001) for differentiating between OC and DNSOI. CRP was more predictive of OC than WCC (P = 0.017). 7/26 (26.9%) OC patients with fever also had an elevated CRP, while 1/23 (4.3%) of DNSOI with fever had a normal CRP. Conclusions An elevated WCC is suggestive of OC. However, a normal WCC can neither exclude nor differentiate between OC and DNSOI. CRP may be a more accurate predictor of OC compared to WCC.