Systemic Inflammation Indices as Hematological Biomarkers of Inflammatory Response in Non-silicotic Workers Exposed to Respirable Silica Dust

This cross-sectional study was performed to assess whether systemic inflammatory indices, including systemic inflammation response index (SIRI), systemic immune‑inflammation index (SII), and aggregate index of systemic inflammation (AISI), can be considered as possible inflammatory markers in silica-exposed workers with no diagnosis of silicosis. We studied 371 non-silicotic workers exposed to respirable silica dust (RSD) and 1422 reference workers. The workers' exposure to RSD were assessed and the inflammatory indices were compared between subgroups of the exposed workers based on the severity and duration of exposure. Correlations between inflammatory indices and the pulmonary function parameters were investigated. Also, the receiver operating characteristic (ROC) curve and Youden index were used to determine the cut-off values of the SII, SIRI, and AISI. Significant dose-response relationships were observed between duration of exposure and all indices except monocytes and LMR. No significant interaction was observed between duration of exposure to RSD and smoking. Borderline significant correlations were observed between AISI and SIRI with forced expiratory volume (FEV1) and FEV1 to forced vital capacity (FVC) ratio. Higher AUCs were obtained for SII and AISI, respectively. The cut-off values for these biomarkers to be considered abnormal were > 348.48 for SII, > 183.78 for AISI, and > 0.768 for SIRI. Overall, the present study showed for the first time, that SII, AISI, and SIRI might be considered as available, easy-to-obtain, and non-expensive markers of inflammation in non-silicotic workers with a long duration of exposure to RSD who are at risk of developing silicosis in subsequent years.