Investigating the association between calcium-phosphorus balance and osteoarthritis: Evidence from NHANES 2007-2016.

The role of the calcium-phosphorus balance in influencing osteoarthritis (OA) risk is not fully understood. This study investigated the relationship between calcium-phosphorus metabolism and OA risk. Data from the National Health and Nutrition Examination Survey spanning 2007 to 2016 were used in this study. Participants aged ≥ 30 years with available serum calcium and phosphorus levels, self-reported OA status, and relevant covariates were included in the study. Multivariable logistic regression analysis was performed to assess the potential influence of calcium-phosphorus metabolism on the risk of OA. Nonlinear relationships were assessed using the restricted cubic spline model. Participants with OA had mildly elevated calcium and phosphorus levels. Concurrently, the calcium-phosphorus (Ca/P) ratio decreased. With confounders adjusted for, the Ca/P ratio was inversely associated with OA risk (odds ratio (OR) = 0.72, 95% CI: 0.56-0.94, P = .017), while serum calcium (OR = 2.12, 95% confidence interval (CI): 0.96-4.68, P = .064) and phosphorus (OR = 1.87, 95% CI: 1.22-2.86, P < .01) were positively associated. The relationship between the Ca/P ratio and risk of OA was significantly influenced by body mass index (P for interaction < .05). The restricted cubic spline model indicated that the Ca/P ratio was nonlinearly associated with OA risk with a threshold of 1.96. Serum calcium level was associated with OA in a U-shaped pattern, with a threshold of 2.35. In contrast, a linear association was observed between serum phosphorus levels. A reduced Ca/P ratio, increased serum phosphorus, and either elevated or decreased serum calcium each contribute to a heightened risk of OA. Imbalances in calcium-phosphorus metabolism may be associated with osteoarthritis risk. Relevant biomarkers, such as serum calcium, phosphorus, and the Ca/P ratio, could serve as potential indicators. Further studies are needed to confirm these findings.