Introduction: Abdominal aortic calcification (AAC) has been associated with poorer bone health and increased fracture risk in varied clinical settings, often in small studies with inconsistent findings. We aimed to synthesise observational studies on the association of AAC with bone mineral density (BMD) and fractures in a systematic review and meta-analysis.
Methods: Articles that reported on associations of AAC with BMD and/or fracture were retrieved from online databases from inception to August 2020. AAC was categorised as any/advanced AAC versus low/no AAC (reference group). The relationships between AAC and BMD at skeletal sites were determined by standardised mean difference [SMD] with 95% confidence intervals [CI]. To determine the association between AAC and risk and risk of any fracture, relative risk [RR] with 95%CI was calculated. Random effects models were applied.
Results: 79 articles (40 providing data for meta-analysis) were included from 2173 articles screened. Moderate quality evidence suggests BMD is lower at the total hip [SMD: -1.05, 95%CI (-1.47 to -0.63); I2 =94%; n=20277], femoral neck [SMD: -0.25 (-0.46 to -0.04); 99%; n=6981] and lumbar spine [SMD: -0.67 (-1.21 to -0.12); 99%; n=17260] in individuals with any/advanced AAC. Moderate quality evidence suggests fractures were more prevalent in individuals with any/advanced AAC [n=3515/14894 versus 2646/14730 (low/no AAC); RR: 1.66 (1.43 to 1.93); 90%]. In prospective studies, any/advanced AAC increased the risk of incident fractures [n=1197/6797 versus 1635/10113; RR 1.40 (1.22 to 1.61); 63%] with lower heterogeneity than seen for prevalent fracture. Findings were similar according to study location and imaging modality, but effects were more pronounced in older women.
Conclusion Moderate quality evidence supports the association of AAC with lower BMD and increased fracture risk. This suggests severe AAC is a risk factor for skeletal fragility and could be combined with BMD to enhance fracture risk prediction.