Value of neutrophil gelatinase-associated lipocalin，osteoprotegerin，receptor activator of nuclear factor-kappa B ligand，and 28-joint disease activity score in predicting osteoporosis in patients with rheumatoid arthritis

Abstract:

Objective：To investigate the value of blood neutrophil gelatinase-associated lipocalin（NGAL），osteoprotegerin（OPG），28-joint disease activity score（DAS28），and receptor activator of nuclear factor-kappa B ligand（RANKL） in predicting osteoporosis in patients with rheumatoid arthritis（RA）. Methods：A total of 119 RA patients were enrolled as RA group，among whom 51 had osteo－porosis in addition to RA，and 68 healthy individuals were enrolled as control group. ELISA was used to measure NGAL，OPG（an index for bone formation），and RANKL（an index for bone resorption） for both groups，and bone mineral density（BMD），DAS28，and clinical and laboratory data were recorded in detail. Results：Compared with the control group，the RA group had significantly higher serum levels of NGAL and RANKL（both P=0.000） and significantly lower serum OPG level，OPG/RANKL ratio，and BMD（all P=0.000）. Compared with those without osteoporosis，the RA patients with osteoporosis had sig－nificantly higher serum NGAL（152.12±28.34 ng/mL vs. 124.50±18.52 ng/mL，P=0.000），serum RANKL level（112.23±18.45 pmol/L vs. 103.89±14.14 pmol/L，P=0.008），and DAS28 score（4.21±0.56 vs. 3.52±0.70，P=0.000），as well as significantly lower serum OPG（114.35±17.00 ng/L vs. 120.56±15.35 ng/L，P=0.039），OPG/RANKL ratio（1.06±0.24 vs. 1.18±0.24，P=0.006），and BMD（-3.73±0.69 vs. -0.57±0.76，P=0.000）. Spearman correlation analysis showed that NGAL and DAS28 were positively correlated with the severity of BMD（rs=0.532 and 0.437，P=0.000 and 0.000），and such correlation had a certain value in the early diagnosis of osteoporosis in RA patients. The area under the receiver operating characteristic curve showed that DAS28 with a cut-off value of 4.11（a sensitivity of 68.6% and a specificity of 77.9%），NGAL with a cut-off value of 148.80 ng/mL（a sensitivity of 60.8% and a specificity of 89.7%），and RANKL with a cut-off value of 100.77 pmol/L（a sensitivity of 64.7% and a specificity of 54.4%） helped with the diagnosis of osteoporosis in RA patients. Conclusion：Serum levels of the inflammatory markers NGAL and RANKL and DAS28 score at their respective cut-off values can help with the diagnosis of osteoporosis in RA patients. They also have a certain clinical value in adjustment of treatment regimens and early intervention of osteoporosis.