Regional distribution of spine and hip QCT BMD responses after one year of once-monthly ibandronate in postmenopausal osteoporosis

In the published placebo-controlled Ibandronate Quality (IQ) study, 12 months of once-monthly oral ibandronate increased femoral and vertebral integral and trabecular bone mineral density (BMD) measured by quantitative computed tomography (QCT). Ibandronate showed significant improvements versus placebo in finite element analysis of femoral and vertebral strength. This post hoc analysis examined QCT BMD changes in novel superior and inferior vertebral volumes of interest (VOIs) and femoral and vertebral subcortical, extended cortical, and extended trabecular VOIs. Ninety-three postmenopausal women (BMDaT-scores ≤ − 2.0 at lumbar spine, total hip, or femoral neck) received ibandronate 150 mg/month (n = 47) or placebo (n = 46) for 12 months. QCT with Medical Imaging Analysis Framework (MIAF)-Spine and MIAF-Femur used automated segmentation and coordinate system-based identification of integral, cortical, subcortical, and trabecular VOIs and combinations (extended cortical = cortical + subcortical; extended trabecular = trabecular + subcortical). Between-group differences in mean percentage changes from baseline were determined by treatment- and center-adjusted analysis of variance. P values were post hoc, exploratory, descriptive, and unadjusted for multiple comparisons. Ibandronate increased vertebral superior and inferior trabecular and extended cortical midsection BMD (4.9%, p = 0.032; 4.6%, p = 0.055; 3.9%, p = 0.014, respectively) versus placebo. Femoral BMD treatment differences (ibandronate versus placebo) were significant in total hip (extended trabecular 4.0%, p = 0.005; extended cortical 1.5%, p = 0.047; subcortical 3.7%, p = 0.009), trochanter (extended trabecular 5.2%, p = 0.007; extended cortical 2.4%, p = 0.01), and extended trabecular femoral neck (4.0%, p = 0.02). Monthly oral ibandronate for 12 months improved QCT BMD versus placebo in the vertebral periphery, subcortical total hip, and all femoral extended trabecular regions.