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  • In the normal BMD subgroup there was progressive bone loss

    2019-05-13

    In the normal BMD subgroup, there was progressive bone loss over 3 years at the spine and hip (5.4% and 4.5%, respectively). This finding is consistent with the ATAC data [5]. Two patients required alendronate triggered by clinical events but there were no algorithm triggered events. There were no non-traumatic fractures reported in the osteopaenic group receiving alendronate compared with 8% in the group without alendronate. The osteoporotic patients would be presumed to have a higher fracture rate than the osteopaenic group associated with lower baseline BMD. The non-traumatic fracture rate in the osteoporotic group receiving alendronate was lower in comparison to the osteopaenic group without alendronate. Overall this suggests a protective effect of alendronate. However, these results should be interpreted with caution because the study was not adequately powered to detect a difference in fracture rates. Eleven osteopaenic patients progressed to thiostrepton with T scores ≤−2.5 but this was not observed for patients with a normal baseline BMD. The intervention rate, with the Osteoporosis Australia Algorithm, for introducing alendronate to the patients with osteopaenia (15.1%) was lower than we had expected. Given that 27% of Australian women aged 60 and over are considered osteoporotic and 51% [7] are osteopaenic, it was expected that approximately 75% of women accrued would require bisphosphonate therapy. The high rate, 8%, of low trauma fractures we observed in osteopaenic patients without alendronate suggests that the algorithm threshold may be set too high in this group. In the ATAC study, fracture rates were constant during the period of treatment [9]. More fractures were reported in the anastrozole than tamoxifen group but then were similar after the completion of treatment. There was no protocol for bone health maintenance in this study and bisphosphonate use was low at 10% and 7% in these groups respectively [3]. Our patients in the osteopaenic group receiving early intervention had a mean BMD of 1.009g/cm2, equivalent to a T score of −1.7. The ATAC sub-study found that 5 women with osteopaenia at baseline (4 in the anastrozole group and 1 receiving tamoxifen) developed osteoporosis. They evaluated the T-scores from baseline to 5 years with linear regression, and found that a T-score of −1.5 may define risk for the development of osteoporosis as no patients with a higher T-score dropped to −<2.5 on treatment [5]. The UK expert group have suggested an alternative algorithm. In postmenopausal women with a T-score that falls below −2.0 or if the rate of bone loss is more than 4% per year with pre-existing osteopenia, a bisphosphonate is recommended [13]. This pragmatic recommendation avoids the need to measure uNTx which is expensive and unwieldy. A simplified algorithm, omitting uNTx but taking into account major risk factors for osteoporotic fracture may have more clinical utility. Vitamin D deficiency is common in our community and contributes adversely to bone health, and to breast cancer outcomes. It is associated with reduced BMD and osteoporosis. Although most studies focused on the elderly population, appropriate vitamin D supplementation is an important modifiable risk factor for reducing falls and fractures [14]. All the participants in our trial received 400–500IU of oral vitamin D daily regardless of their baseline vitamin D levels. One third of our patients had vitamin D deficiency. We did not see a gradient in mean vitamin D levels between patients from more northerly states and Southern Victoria. This high level of vitamin D deficiency in our patients is comparable to that found in our community regardless of season and latitude. The reported prevalence of vitamin D insufficiency (≤50nmol/L) in women during winter/spring was 40.5%, and 37.4% in southeast Queensland (latitude 28.2°S), and Geelong (38°S) [15]. According to the Working Group of the Australian and New Zealand Bone and Mineral Society, Endocrine Society of Australia and Osteoporosis Australia, higher doses of vitamin D up to 3000–5000IU daily for 6–12 weeks are required to replete body stores, followed by 1000IU daily as maintenance [16]. Treatment of vitamin D deficiency was a decision of the investigator clinician.