Association Between Indices of Peripheral Blood Inflammation and Cavitary Pulmonary Tuberculosis

Objective: To explore inflammation markers of C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammatory index (SII), and systemic inflammatory response index (SIRI) in the differential diagnosis of cavitary pulmonary tuberculosis (PTB) from non-cavitary PTB.

Methods: This retrospective study included 1233 patients with PTB, 518 patients were diagnosed with cavitary PTB as case group, while 715 patients which diagnosed with non-cavitary PTB were selected as control group. The clinical data of patients was collected and the levels of inflammation indices were measured. Receiver operating characteristic (ROC) curve analysis was used to assess the diagnosis and analysis of selected indices. Logistic regression analysis was performed to evaluate the factors associated with cavitary PTB.

Results: The CRP, NLR, MLR, PLR, SII, and SIRI in the case group were significantly higher than those in the controls (all <0.001). When cavitary PTB was taken as the endpoint, the optimal diagnostic thresholds of CRP was 35.365 (area under the ROC curve (AUC)=0.601), NLR was 5.740 (AUC=0.595), MLR was 0.525 (AUC=0.577), PLR was 198.255 (AUC=0.602), SII was 1252.045 (AUC=0.628), and SIRI was 2.095 (AUC=0.605), respectively. Logistic regression analysis showed that gender, CRP, PLR, and SIRI were the independent risk factors for cavitary PTB. The sensitivity of the combination of the three indices (CRP+PLR, CRP+SIRI, PLR+SIRI, and CRP+PLR+SIRI) were higher than those of the CRP, PLR, and SIRI.

Conclusion: CRP, PLR, and SIRI levels were associated with an increased likelihood of cavitary PTB. The combined detection of CRP, PLR, and SIRI is promising as a screening marker and may be useful for ruling out PTB with cavitary.