Role of BMI and age in predicting pathologic vertebral fractures in newly diagnosed multiple myeloma patients: A retrospective cohort study

Vertebral fractures affect approximately 30% of myeloma patients and lead to a poor impact on survival and life quality. In general, age and body mass index (BMI) are reported to have an important role in vertebral fractures. However, the triangle relationship among age, BMI, and vertebral fractures is still unclear in newly diagnosed multiple myeloma (NDMM) patients. This study recruited consecutive 394 patients with NDMM at Taipei Veterans General Hospital between January 1, 2005 and December 31, 2015. Risk factors for vertebral fractures in NDMM patients were collected and analyzed. The survival curves were demonstrated using Kaplan-Meier estimate. In total, 301 (76.4%) NDMM patients were enrolled in the cohort. In the median follow-up period of 18.0 months, the median survival duration in those with vertebral fractures ≥ 2 was shorter than those with vertebral fracture < 2 (59.3 vs 28.6 months; P = 0.017). In multivariate Poisson regression, BMI < 18.5 kg/m² declared increased vertebral fractures compared with BMI ≥ 24.0 kg/m² (adjusted RR, 2.79; 95% CI, 1.44–5.43). In multivariable logistic regression, BMI < 18.5 kg/m² was an independent risk factor for vertebral fractures ≥ 2 compared with BMI ≥ 24.0 kg/m² (adjusted OR, 6.05; 95% CI, 2.43–15.08). Among age stratifications, patients with both old age and low BMI were at a greater risk suffering from increased vertebral fractures, especially in patients > 75 years and BMI < 18.5 kg/m² (adjusted RR, 12.22; 95% CI, 3.02–49.40). This is the first study that demonstrated that age had a significant impact on vertebral fractures in NDMM patients with low BMI. Elder patients with low BMI should consider to routinely receive spinal radiographic examinations and regular follow-up.