Clinical investigation of C-terminal cross-linking telopeptide test in prevention and management of bisphosphonate-associated osteonecrosis of the jaws.

PURPOSE: The aim of this study was to determine, in a clinical setting, the effectiveness of the C-terminal cross-linking telopeptide test (CTX) test in the prevention and management of osteonecrosis of the jaws (ONJ) in patients taking bisphosphonates. PATIENTS AND METHODS: A total of 348 patients underwent a fasted morning CTX test. Of these, 222 were patients at risk of ONJ who had been referred for extractions, 15 had ONJ, and 113 were controls.
RESULTS: The 215 patients taking long-term oral bisphosphonates were older (71 +/- 11.6 years), were predominantly women with osteoporosis, and were medically compromised. The average CTX value was 238 +/- 144 pg/mL, with 98 having a value less than 200 pg/mL. One patient with a CTX value of 126 pg/mL developed ONJ after an extraction. Seven intravenous bisphosphonate patients underwent extractions with no cases of ONJ developing. The CTX value was 329 +/- 354, with 4 less than 200 pg/mL. Fifteen patients developed ONJ, 12 after extractions and 3 spontaneously. Of these, 7, who were still taking a bisphosphonate at presentation, had a CTX value of 116 pg/mL. A CTX value of less than 150 pg/mL did not correlate with the clinical risk factors of age, gender, comorbidities, bone disease, or bisphosphonate duration. A statistically significant difference in the CTX value was found for those taking alendronate compared with those taking risedronate (P < .0001). If the bisphosphonate was ceased, the CTX value increased at approximately 25 pg/mL per month.
CONCLUSIONS: The CTX test is not predictive of the development of ONJ for an individual patient but does identify those in the "risk zone," which is a value of less than 150 pg/mL to 200 pg/mL. If medically appropriate, the bisphosphonate can be ceased so that the CTX value increases to bring the patient out of the "risk zone."