Interaction effects of significant risk factors on low bone mineral density in ankylosing spondylitis

PeerJ. 2023 Nov 22:11:e16448. doi: 10.7717/peerj.16448. eCollection 2023.

Abstract

Background: To analyze individually and interactively critical risk factors, which are closely related to low bone mineral density (BMD) in patient with ankylosing spondylitis (AS).

Methods: A total of 249 AS patients who visited China-Japan Friendship Hospital were included in this training set. Patients with questionnaire data, blood samples, X-rays, and BMD were collected. Logistic regression analysis was employed to identify key risk factors for low BMD in different sites, and predictive accuracy was improved by incorporating the selected significant risk factors into the baseline model, which was then validated using a validation set. The interaction between risk factors was analyzed, and predictive nomograms for low BMD in different sites were established.

Results: There were 113 patients with normal BMD, and 136 patients with low BMD. AS patients with hip involvement are more likely to have low BMD in the total hip, whereas those without hip involvement are more prone to low BMD in the lumbar spine. Chest expansion, mSASSS, radiographic average grade of the sacroiliac joint, and hip involvement were significantly associated with low BMD of the femoral neck and total hip. Syndesmophytes, hip involvement and higher radiographic average grade of the sacroiliac joint increases the risk of low BMD of the femoral neck and total hip in an additive manner. Finally, a prediction model was constructed to predict the risk of low BMD in total hip and femoral neck.

Conclusions: This study identified hip involvement was strongly associated with low BMD of the total hip in AS patients. Furthermore, the risk of low BMD of the femoral neck and total hip was found to increase in an additive manner with the presence of syndesmophytes, hip involvement, and severe sacroiliitis. This finding may help rheumatologists to identify AS patients who are at a high risk of developing low BMD and prompt early intervention to prevent fractures.

Keywords: Ankylosing spondylitis; Femoral neck; Hip involvement; Interaction effect; Low bone mineral density; Prediction model; Risk factor; Sacroiliitis; Syndesmophytes; Total hip.

MeSH terms

  • Bone Density
  • Bone Diseases, Metabolic* / complications
  • Humans
  • Osteoporosis* / etiology
  • Risk Factors
  • Spondylitis, Ankylosing* / complications

Grants and funding

The study received funding from the National High Level Hospital Clinical Research Funding (No. 2022-NHLHCRF-LX-02-0104), the National Science Foundation of Beijing, China (No. 7182148) the Beijing Traditional Chinese Medicine Science and Technology Development Fund Project (No. JJ-2020-87) and the Spondylitis Association of America. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.