Clinical Significance of Hematological Indices as Disease Activity Markers in Patients With Ankylosing Spondylitis Following Treatment With Tumor Necrosis Factor Inhibitors.

BACKGROUND: The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score with C-reactive protein (ASDAS-CRP) are commonly used to measure disease activity in patients with AS.

AIM: This study was conducted to determine the power of hematological indices to serve as disease activity markers in AS patients treated with tumor necrosis factor (TNF) inhibitors.

METHODS: A total of 222 patients with AS were recruited and classified into active disease (BASDAI ≥ 4, n = 158) and remission (BASDAI < 4, n = 64) groups. The active group was treated with TNF inhibitors for 3 months. Composite indices such as BASDAI and ASDAS-CRP were measured to assess disease activity. Hematological indices as alternative disease activity markers including neutrophil-to-lymphocyte ratio (NLR), neutrophil-to-hemoglobin and lymphocyte (NHL) score, systemic immune-inflammation index (SII), and platelet-to-lymphocyte ratio (PLR) were assessed.

RESULTS: Patients with active AS showed higher NLR, NHL score, SII, and PLR than those in remission. ASDAS-CRP and BASDAI values at baseline were significantly associated with all hematological indices, including NLR, NHL score, SII, and PLR. Similar to the improvement of BASDAI and ASDAS-CRP scores following TNF inhibitors treatment, NLR, NHL score, SII, and PLR markedly decreased after treatment with TNF inhibitors for 3 months (p < 0.001 for all, respectively). All hematological indices closely predicted major improvement (∆ ≥ 2.0 of ASDAS-CRP) following treatment with TNF inhibitors.

CONCLUSION: This study indicated that four hematological indices may be useful markers of disease activity and predictors of treatment response to TNF inhibitors in patients with AS. Further studies in larger populations are needed to validate the usefulness of hematological indices as measures of disease activity in patients with AS.