Association between renal function and fracture incidence during treatment with teriparatide or alendronate: an exploratory subgroup analysis of the Japanese Osteoporosis Intervention Trial-05.

The association of renal function with fracture incidence during teriparatide or alendronate treatment in elderly Japanese women was examined. Fracture incidence differed by fracture type, renal function, and treatment protocol. The results provide important information on pharmacotherapy in clinical practice for osteoporosis.

Purpose: Incidence rate of morphometric vertebral fracture was lower under treatment with once-weekly teriparatide (TPTD) followed by alendronate (ALN) than under treatment with ALN throughout the study among elderly Japanese women at high fracture risk in JOINT-05. This is an exploratory subgroup analysis according to chronic kidney disease (CKD) status at baseline.

Methods: Participants received sequential therapy with TPTD for 72 weeks, followed by ALN for 48 weeks (TPTD-ALN group, N = 483) or ALN monotherapy for 120 weeks (ALN group, N = 496). Baseline CKD status was classified by the estimated glomerular filtration rate (eGFR) and categorized as: CKD 1/2 (eGFR ≥ 60 mL/min/1.73 m²), CKD 3a (eGFR 45-59 mL/min/1.73 m²), or CKD 3b/4 (eGFR < 45 mL/min/1.73 m²). Incidences of vertebral fractures including morphometric fractures, non-vertebral fractures, and all fractures were evaluated during follow-up.

Results: Baseline characteristics were not different between treatment groups. Higher stages of CKD were associated with age and number of prevalent vertebral fracture. In CKD 1/2 patients (N = 556 with 90 incidents of morphometric vertebral fracture), the incidence of vertebral fractures was lower in the TPTD-ALN group than in the ALN group (p = 0.01). In CKD 3b/4 patients (N = 112 with 10 incidents of non-vertebral fracture), the incidence of non-vertebral fractures was lower in the ALN group than in the TPTD-ALN group, although the number of fractures was small. In the ALN group, the incidences of vertebral fractures, non-vertebral fractures, and all fractures remained constant across CKD stages.

Conclusion: This exploratory analysis showed that fracture incidence on ALN was constant regardless of renal function. It also suggested that the incidence of vertebral fractures on TPTD-ALN was lower than ALN monotherapy in CKD 1/2 patients. These results provide important information for drug selection in the clinical practice of osteoporosis.