Changes in C-reactive protein, erythrocyte sedimentation rate, human leukocyte antigen-B27, and immunoglobulins A, G, M in patients with ankylosing spondylitis

Abstract Background To explore the changes in C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), human leukocyte antigen-B27 (HLA-B27), and immunoglobulin (Ig) (IgA, IgG, and IgM) in patients suffering from ankylosing spondylitis (AS). Methods A total of 232 patients with axial spondyloarthritis admitted from January 2020 to December 2021 were selected, among whom 132 were AS patients (AS group) and 100 were non-AS cases (non-AS group). Meanwhile, 100 healthy subjects undergoing physical examination were included as a control group. Peripheral blood was collected to detect the levels of CRP, ESR, HLA-B27, IgA, IgG, and IgM. Results The positive rates and levels of CRP, ESR, HLA-B27, IgG, and IgM in non-AS and AS groups were significantly higher, and the IgA level of the AS group was higher than those of the control group (P<0.05). The AS group had significantly higher positive rates and levels of CRP, ESR, HLA-B27, and IgA than those of the non-AS group (P<0.05). The levels of HLA-B27, ESR and CRP had positive correlations with those of IgA, IgG and IgM (P<0.05). The area under the curve (AUC) of HLA-B27 with a cut-off value of 53.18 U/mL for the diagnosis of AS was 0.879. AUC of ESR with a cut-off value of 23.83 mm/h for the diagnosis of AS was 0.811. AUC of CRP with a cut-off value of 14.35 mg/L for the diagnosis of AS was 0.745. With the cut-off values of 2.75 g/L, respectively, AUC of IgA for the diagnosis of AS were 0.668. AUC of the combined diagnosis was 0.929 (P<0.05). Conclusions AS patients have abnormally elevated levels of HLA-B27, ESR, CRP, and IgA, and the combined detection has a higher diagnostic value. The abnormal increase in IgA, IgG, and IgM is positively correlated with rheumatic inflammation marker HLA-B27, CRP, and ESR.