Serum Levels of OPG, RANKL, and RANKL/OPG Ratio in Patients with Ankylosing Spondylitis: A Systematic Review and Meta-analysis

ABSTRACT

Objectives: To investigate the role of osteoprotegerin (OPG), receptor activator of nuclear factor-kB ligand (RANKL), and RANKL/OPG ratio in the pathogenesis of ankylosing spondylitis (AS).

Methods: Studies that compared serum levels of OPG, RANKL, and RANKL/OPG ratio between AS patients and healthy controls were gathered. Pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated by the random-effects model.

Results: Twenty studies containing 1592 AS patients and 1064 healthy controls were included in this meta-analysis. Serum levels of OPG, RANKL, and RANKL/OPG ratio in AS patients were significantly higher than that in normal controls (OPG: SMD = 0.401, 95%CI = 0.026–0.777, p = 0.036; RANKL: SMD = 1.116, 95%CI = 0.510–1.723, p < 0.001; RANKL/OPG ratio: SMD = 0.691, 95%CI = 0.084–1.299, p = 0.026, respectively). Subgroup analysis suggested that Asian AS patients and patients with elevated ESR (ESR >20 mm/h) had higher serum OPG levels compared to normal controls. Asian patients, CRP >10 mg/L, ESR >20 mm/h, duration of disease ≤8 years, and BASDAI score >4 points subgroups showed increased RANKL levels compared to controls.

Conclusions: Serum levels of OPG, RANKL, and RANKL/OPG ratio may be used as potential susceptible biomarkers for AS, but they could be influenced by race, inflammatory factors, and disease activity of AS patients.

KEYWORDS:

• Ankylosing spondylitis
• OPG
• RANKL
• bone metabolism
• meta-analysis

Acknowledgments

Thanks for the people who participated in this study. This work was supported by <the National Natural Science Foundation of China> under Grant <number 30972530, 81273169, 81573218 and 81773514>; <Funding for scientific research activities of academic and technical leaders in Anhui Province> under Grant <number 2017D140>.

Disclosure of interest

The authors report no conflict of interest.

Supplementary material

Supplementary data can be accessed here.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under Grant [30972530, 81273169, 81573218, 81773514]; the Funding for scientific research activities of academic and technical leaders in Anhui 265 Province under Grant [2017D140].