Abstract
BACKGROUND: Numerous studies have demonstrated shared risk factors and pathophysiologic mechanisms between osteoporosis and cardiovascular disease. High-density lipoprotein cholesterol (HDL-C) and platelets have long been recognized as crucial factors for cardiovascular health. The platelet to HDL-C ratio (PHR) combines platelet count and high-density lipoprotein cholesterol (HDL-C) level, It is a novel biomarker for metabolic syndrome and cardiovascular disease. The platelet to HDL-C ratio (PHR) possibly reflects the balance between proinflammatory and anti-inflammatory states in the body. Therefore, we hypothesized that changes in PHR ratios may predict a predisposition to pro-inflammatory and increased bone resorption. However, the relationship between the platelet to HDL-C ratio (PHR) and bone mineral density (BMD) remains insufficiently understood. This study aimed to elucidate the relationship between the platelet to HDL-C ratio (PHR) index and bone mineral density (BMD). METHODS: Data from the NHANES 2005-2018 were analyzed, excluding adults with missing key variables and specific conditions. Nonlinear relationships were explored by fitting smoothed curves and generalized additive models, with threshold effects employed to calculate inflection points. Additionally, subgroup analyses and interaction tests were conducted. RESULTS: The study included 13,936 individuals with a mean age of 51.19 ± 16.65 years. Fitted smoothed curves and generalized additive models revealed a nonlinear, inverted U-shaped relationship between the two variables. Threshold effect analysis showed a significant negative association between PHR and total femur bone mineral density (BMD) beyond the inflection point of platelet to HDL-C ratio (PHR) 33.301. Subgroup analyses showed that a significant interaction between these two variables was observed only in the age and sex subgroups (P-interaction < 0.05). CONCLUSIONS: Our study identified a complex, nonlinear, inverted U-shaped relationship between platelet to HDL-C ratio (PHR) and total femur bone mineral density (BMD). These findings underscore the importance of maintaining optimal PHR levels to support bone health, especially in high-risk populations.