A threshold effect of Apolipoprotein A1 levels on systemic inflammatory response index in individuals with osteoporotic fractures: a cross-sectional study

Chronic inflammation and lipid metabolism are closely associated with osteoporotic fractures. Previous studies have reported associations between Apolipoprotein A1 (ApoA1) and inflammatory markers in specific inflammatory diseases. Nevertheless, the association between ApoA1 and the Systemic Inflammatory Response Index (SIRI) has been scarcely investigated in populations with osteoporotic fractures. We therefore conducted this cross-sectional study to examine this association.

In this cross-sectional study, 2067 patients with osteoporotic fractures (OPF) needing surgical intervention at Kunshan Hospital affiliated with Jiangsu University from January 2017 to July 2022 were enrolled. The relationship between serum ApoA1 concentrations and SIRI was evaluated and described using linear regression models and smooth curve fitting. A two-piecewise linear regression model was employed to identify the inflection point. Additionally, stratified and univariate analyses were conducted.

After accounting for potential confounders, serum ApoA1 concentrations were discovered to have an inverse association with SIRI (β = -0.822, 95% CI (-1.491, -0.153), P = 0.016). Moreover, the smoothed plot revealed a non-linear relationship between serum ApoA1 concentrations and SIRI, with the inflection point observed at ApoA1 levels of 1.25 g/L. The magnitude of effect and 95% CI on either side of the inflection point were -2.258 (-3.541, -0.974) and 0.512 (-0.706, 1.729), respectively. In addition, further subgroup analyses reinforced the consistency of the association between ApoA1 concentrations and SIRI.

Our study revealed a threshold effect between serum ApoA1 levels and SIRI in patients with OPF, demonstrating a negative correlation between ApoA1 and SIRI within a specific range. However, further research is warranted to expand and validate these findings.