Risk assessment of bisphosphonate-related osteonecrosis of the jaw: significance of measurement of urinary cross-linked C-telopeptide of type I collagen

Abstract

We measured urinary cross-linked C-telopeptide of type Ⅰ collagen(CTX)in 72 patients who were receiving bisphosphonate(BPs)treatment to investigate the risk of BPs-related osteonecrosis of the jaw(ONJ). Thirty-six of the 72 patients had developed ONJ, and the other 36 had not. Urine was collected after an overnight fast, and the CTX level was measured by enzyme-linked immunosorbent assay as creatinine-converted values(Crconverted values). The mean Cr-converted value in the BPs-treated patients tended to be lower than the standard value. The CTX level in the group with ONJ was significantly lower than that in the group without ONJ(p ＜ 0.001). The cutoff value of CTX as measured by the ROC curve was 98 Cr-converted values for the risk assessment of ONJ. The Cr-converted value was 98 or lower in 29 of/36 patients(81 ％)in the group with ONJ. In contrast, the Cr-converted value was higher than 98 in 28 of/36 patients(78 ％)in the group without ONJ. Therefore, the risk of developing ONJ is high when the Cr-converted value of the CTX level is 98 or lower. The CTX value in the injection prescription group was lower than that in the oral prescription group(P ＝ 0.020). The CTX level was also lower in the A group concurrently receiving steroids(P ＜ 0.001)and the group concurrently receiving steroids and anticancer drugs(P ＝ 0.023)as compared with patients not receiving these drugs. These findings suggest that urinary CTX measurement is useful for assessing the risk of developing BPs-related ONJ.