Bone turnover markers (BTMs) are useful to monitor response and adherence to osteoporosis treatment. However, the relationship between risedronate-related suppression of BTMs and corresponding increases in bone mineral density (BMD) is still unclear. This study further explored the nature of these relationships. Sub-analysis included 800 subjects of a Japanese phase III study in the patient with once monthly risedronate 75 mg treatment of 12 months who were measured of vertebral BMD, serum TRACP-5b (Tartrate-resistant acid Phosphatase 5b) and serum BAP (Bone alkaline phosphatase). The minimal significant change (MSC) was set at 12.4% for TRACP-5b and 23.1% for BAP. The subjects were divided into subgroups according to change in TRACP-5b or BAP at 1 and 3 months, i.e., into Group L (reduction more than MSC), Group N (change within MSC) and Group H (elevation more than MSC). Percent change in BMD at 12 months was compared among these subgroups. In TRACP-5b at 3 months, BMD gain was significantly greater in the Group L than the other groups (Group L [N=661] 6.24±4.11%, Group N [N=99] 4.38±4.50%, Group H [N=33] 2.15±4.21%, One-way ANOVA: P < 0.0001). In BAP at 3 month, BMD gain was significantly greater in the Gtoup L than other groups (Group L [N=463] 6.52±4.02%, Group N [N=332] 4.97±4.47%, Group H [N=7] 2.26±3.13%, One-way ANOVA: P < 0.0001). In summary, increases in BMD by risedronate treatment at 12 months were greater in the patient groups showing early reduction in TRACP-5b or BAP by more than MSC. This result suggests that serial measurements of BTMs at baseline and 3 months can be utilised in predicting future BMD gain by risedronate.
Disclosure: The authors declared no competing interests. This work was partially supported by JSPS KAKENHI Grant Number 24592269.