Fracture Risk Assessment in Patients with Monoclonal Gammopathy of Undetermined Significance: Value of Bone Mineral Density and Trabecular Bone Score

Patients with gammopathy of undetermined significance (MGUS) were unable to be classified by bone mineral density (BMD) and trabecular bone score (TBS), according to a study presented at the 17^th International Myeloma Workshop.

In this retrospective study, the researchers identified 115 adults diagnosed with MGUS between 2005 and 2018 that had lumbar spine x-rays beginning 24 months prior to MGUS diagnosis. They ascertained MGUS diagnoses using the 2003 IMWG criteria. Subsequently, they matched a control group 1:1 for sex, age, and BMI.  Participants were excluded from the study if they had the presence of primary or metastatic bone malignancy, multiple myeloma (MM), exposure to anti-resorptive or anabolic agents, or exposure to steroids for over three months. TBS values were classified as low (<1.20), intermediate (1.20 – 1.35), or normal (>1.35), and the researchers retrospectively performed TBS analysis using TBS iNsight v3.0 software.

Following data analysis, the results of the study showed that BMD patients had notably higher incident fractures juxtaposed to the control group (14 vs. 7, respectively; P<0.05). The researchers observed no difference between cases and controls as it pertained to the TBS categories (low 23 vs. 15%; intermediate 42 vs. 41%; normal 35 vs. 44%; P=0.22) or LS T-scores (0.30 vs +0.22, P=0.16).

Moreover, although fractures occurred in controls who had a significantly lower TBS value (1.17 vs. 1.34 in controls with vs. without fracture, respectively, P<0.01), the results showed this was not the case in patients with MGUS.

“Despite a significantly increased risk of fractures in patients with MGUS compared to age-, sex- and BMI-matched controls, neither BMD nor TBS, obtained within 2 years of MGUS diagnosis, were able to risk stratify patients,” the research authors wrote. “Indeed, unlike controls, patients with MGUS tend to fracture despite a normal BMD and an intermediate or normal TBS value. More advanced non-invasive measures of bone quality and finite element analysis may be needed to capture this risk.”

Sfeir J, et al. Fracture Risk Assessment in Patients with Monoclonal Gammopathy of Undetermined Significance: Value of Bone Mineral Density and Trabecular Bone Score.

Presented at the 17^th International Myeloma Workshop; September 12-15, 2019; Boston, MA.