Predicting the progression of vertebral fractures in patients with multiple myeloma.

Background Context: Patients with multiple myeloma (MM) incur significant degradation in quality of life because of progressive osteolytic vertebral fractures. No studies have investigated predictors of fracture progression, and limited data are available for predicting the development of future fractures.

Purpose: The purpose of this study was to identify independent predictors of vertebral fracture progression and the development of future vertebral fracture.

Study Design/setting: This is a consecutive retrospective chart review at a single tertiary-care center.

Patient Sample: Patients with MM and pathologic vertebral fracture with radiographic follow-up between January 2007 and December 2013 were included. Radiographic measurements were recorded at presentation with fracture and first follow-up (FFU) after at least three months. Patients with a history of vertebral fracture not associated with MM were excluded.

Outcome Measures: The primary outcome measure was the rate of vertebral body height loss. The development of future vertebral fracture was secondary.

Methods: Anterior, middle, and posterior vertebral body heights were measured from midline sagittal T1-weighted magnetic resonance imaging (MRI). Future fracture-free survival was calculated using Kaplan-Meier analysis. Multivariable regression was used to identify independent predictors of the rate of vertebral height loss. Multivariable Cox proportional hazards modeling was used to identify predictors of developing future vertebral fracture.

Results: Thirty-three patients with 67 fractures were followed for a median of 10.8 months to FFU. Sixty-four percent of the patients were female and the median age was 66. The median additional vertebral height loss between presentation and FFU was 15%, whereas the median rate of vertebral height loss was 1.01%/month. More rapid vertebral height loss was predicted by dyslipidemia (β=0.36, p=.05), previous non-vertebral pathologic fracture related to MM (β=0.51, p=.01), and Durie-Salmon Stage III (β=0.66, p=.06). The median time to future fracture was 25.1 months; the 5-year future fracture-free survival rate was 34%. Osteopenia/osteoporosis (hazard ratio [HR]: 9.28, p<.01), serum light chains (HR: 1.37, p=.06), and serum calcium (HR: 1.62, p=.05) predicted the development of future vertebral fracture.

Conclusions: We observed significant fracture progression over a short follow-up period. Several comorbidities and laboratory measures predicted more rapid vertebral height loss and the development of future fracture. Identifying risk factors for increased fracture burden may allow spine specialists to pursue earlier and appropriate intervention to optimize function and minimize morbidity.