Determination of the Impact of Functional Instability of Parathyroid Hormone and the Calcium-Phosphorus Ratio as Risk Factors during Osteoarthritic Disorders using Receiver Operating Characteristic Curves

Abstract

Backgrounds: The disease risk factor prediction with calcium-phosphorus ratio (CPR) and/or parathyroid hormone (PTH) levels are suitable biomarkers. The aim of the present study was to investigate the functional instability of these biomarkers in the blood on the risk of osteoarthritic disorder (OAD) by using receiver operating characteristic (ROC) curves. Methods: Separate evaluations were performed for subjects 132 with OAD and 109 without OAD symptoms using questionnaires, standardized physical and radiographic examinations, and risk factor identification (hypoparathyroidism, hypocalcaemia and hyperphosphatemia diseases). The blood levels of PTH, calcium, and phosphorus were measured by using appropriate kits. ROC curve and logistic regression analyses were performed for the PTH and CPR levels. Results: The area under the ROC curve (AUC), 95% CI for the AUC, for the OAD compared with the non-OAD cohorts were 0.985, 0.969-1.000, and P<0.001 for the PTH analysis and 0.579, 0.506-0.652, and P<0.05 for the CPR analysis. In the OAD cohort, the AUC and the PTH risk were higher for men than for women; AUC=1.000 for men, and AUC=0.977 for women, with both AUC values highly significant (P<0.001). The CPR risk was higher for men (AUC=0.614, 95% CI=0.483-0.746, P=0.079) than for women (AUC=0.516, 95% CI=0.419-0.613, P=0.736) but was not statistically significant in either sex. Conclusion: A functional instability risk that is higher in male than female OAD cohorts causes lower PTH and CPR levels during OADs, which can be considered one of the OAD diagnostic protocols besides radiological images.