Compared with bone mineral density (BMD) alone, trabecular bone score (TBS) with BMD increases identification of abnormal bone in women with fracture, according to study results published in Osteoporosis International.

Researchers linked clinical dual-energy x-ray absorptiometry (DXA) data to population databases in Manitoba, Canada. Women aged ≥50 years who had their first DXA between February 1999 and March 2018 were eligible for inclusion in the study. Eligible participants also had complete TBS and fracture data, extracted from electronic health records. Fractures were defined as any fracture — excluding those from high trauma and those of the head, neck, hands, feet, and ankle — occurring within 5 years before or after the baseline DXA. Bone status was determined using BMD T-score and TBS. “Normal” bone status was defined as having a BMD T-score of the spine, femoral neck, and total femur ≥-1.0 and TBS >1.31; BMD T-score <-2.5 or TBS <1.23 constituted “abnormal” bone status. The percentage of women with normal BMD as defined by T-score alone was compared with those identified using BMD and TBS. Analyses were stratified by age.

The study cohort included 4649 women who sustained any fracture before baseline DXA and 2547 women who sustained any fracture after baseline DXA. Mean age of women with prior fracture was 66.7±10.0 years. Osteoporotic BMD was present in 1866 (40%) of these women. Using T-score only, 506 (11%) women with prior fracture were classified as having normal BMD. However, when low TBS was added to a BMD score ≤-2.5, the percentage of women with abnormal and normal bone was 61% and 6%, respectively. The percentage of women with abnormal bone status increased with age, from 44% in women aged 50 to 59 years to 83% in women aged ≥80 years (P <.001). Abnormal bone status was also highly prevalent in women with prior hip fracture (80%; P <.001).

Mean age of women with incident fracture was 69.5±10.6 years. Among women with incident fracture, osteoporotic BMD was identified in 1177 (46%), while “normal” BMD was observed in 231 (9%). The percentage of women with normal BMD decreased with age (P <.001). Adding low TBS to bone status assessment decreased the percentage of women with normal bone to 4%. Abnormal bone was detected in 68%. Abnormal bone prevalence increased with age, from 48% in the youngest age group (50-59 years) to 84% in the oldest age group (≥80 years). Abnormal bone status was common in women whose incident fracture occurred at the hip (81%).  


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According to these results, bone status assessment using BMD and TBS vs BMD alone more often identified abnormal bone. A total of 5% in the study cohort had normal bone as defined by BMD and TBS. This percentage was lower among older women and women with hip fractures.

“As most fractures in postmenopausal women occur in those that do not have osteoporosis by BMD T-score alone, the addition of TBS may help guide the important decision to utilize pharmacologic treatment to reduce future fracture risk,” the researchers concluded.

Reference

Binkley N, Morin SN, Martineau P, Lix LM, Hans D, Leslie WD. Frequency of normal bone measurement in postmenopausal women with fracture: a registry-based cohort study. Published online August 10, 2020. Osteoporos Int. doi:10.1007/s00198-020-05576-w