What is the recommended frequency for Dual-Energy X-ray Absorptiometry (DEXA) scan checkups while on Prolia (denosumab)?

From the Guidelines

For patients on Prolia (denosumab), it is recommended to have a DEXA scan before starting treatment and then approximately every 1-2 years while continuing therapy, with the interval based on the change rate of bone mineralization and individual risk factors 1. The American College of Radiology suggests that follow-up DXA scanning is important for monitoring patients who have low BMD, either for progression or therapeutic response, and in those with normal BMD who have increased fracture risk and/or diminishing bone mass 1. Key considerations for DEXA scan frequency include:

• The measurement of hip BMD continues to be the most reliable way of evaluating hip fracture risk, whereas imaging of the spine is optimal for monitoring treatment response 1
• Patients should be scanned on the same DXA machine because differences in vendor technologies prohibit a direct comparison unless cross calibration has been performed 1
• Obtaining a quality BMD measurement every time underscores its importance because it is the BMD values, not T-scores, that are compared between scans 1
• In the majority of patients, the time interval for monitoring is based on the change rate of bone mineralization, which is typically about 2 years; however, it is preferable for this interval to be shorter (1 to <2 years) after therapy has been initiated 1
• Patients who are at high risk for a more rapid decline of bone mass, such as those receiving glucocorticoid therapy, also require shorter intervals between imaging; 1-year intervals after initiation or change of therapy is appropriate with progressively longer intervals once therapeutic effect is established 1
• Scan intervals <1 year are discouraged 1 The goal of DEXA scans in patients on Prolia is to evaluate the effectiveness of the medication in increasing or maintaining bone density, and to inform clinical decisions about continuing therapy 1.

From the Research

DEXA Scan Checkup Frequency While on Prolia

• The frequency of DEXA scan checkups while on Prolia (denosumab) is not explicitly stated in the provided studies, but we can infer some information from the research findings 2, 3, 4, 5, 6.
• In the study by 2, patients with osteoporosis secondary to hypogonadism in prostate carcinoma received denosumab 60 mg subcutaneously every 6 months for 2 years, and their bone mineral density (BMD) was assessed at baseline and after 24 months.
• Another study by 3 evaluated the effectiveness of denosumab in solid organ transplant recipients and found that the mean duration of therapy was 1.65 ± 0.7 years, with BMD assessments performed at baseline and after treatment.
• The FREEDOM trial, cited in 4, assessed the densitometric changes in postmenopausal women with osteoporosis treated with denosumab, with BMD measurements taken at baseline, 12,24, and 36 months.
• A retrospective analysis by 5 examined the factors underlying treatment nonresponses to denosumab in elderly patients following hip fracture, with BMD assessments performed at baseline and after 12 months of treatment.
• A primer for clinicians by 6 highlights the importance of recognizing pitfalls in DXA bone densitometry, including technical, patient, and interpretive factors that can affect BMD measurements.

Factors Influencing DEXA Scan Frequency

• The studies suggest that the frequency of DEXA scan checkups may depend on various factors, such as:
  • Treatment duration and response to denosumab 2, 3, 4, 5
  • Patient population and underlying conditions (e.g., osteoporosis secondary to hypogonadism, solid organ transplantation, postmenopausal osteoporosis) 2, 3, 4
  • BMD measurement techniques and potential pitfalls in interpretation 6
• However, there is no clear consensus on the optimal frequency of DEXA scan checkups while on Prolia, and further research is needed to determine the best approach for monitoring treatment response and adjusting therapy accordingly.