Background: Factors related to the magnitude of BMD response to osteoanabolic treatment remain unclear. Thus, this study evaluated the long-term BMD response rate to osteoanabolic treatment (teriparatide/PTH) in patients with severe osteoporosis and the factors related to inadequate response (IR).
Methods: Fifty-seven patients (52F:5M) aged 67.5±10.7 years receiving teriparatide (50) or PTH1-84 (7) during 18 or 24 months were included (83% had vertebral fractures [median 4], 72% non-vertebral fractures, 97% previously received antiosteoporotic treatment [mean duration 6.2±4.9years], 23% were on glucocorticoid treatment). Bone turnover markers (BTM) (formation: P1NP, bone ALP; resorption: sCTx, NTx) and 25-OHD levels were assessed before and at 3, 6, 12 and 18/24 months of treatment. Lumbar and femoral BMD and spinal X-ray were assessed at baseline, and at 12 and 18/24 months. Previous and incidental fractures, previous antiosteoporotic treatment, risk factors and cause of osteoporosis were recorded in all patients. IR was defined by a lumbar BMD increase <3% at 18/24 months. BTM were evaluated in fold-number over/under normal values and as a normalised bone formation/resorption index.
Results: 32% of patients showed IR, presenting higher baseline lumbar BMD values (0.824±0.156 vs. 0.733±0.140g/cm2, p=0.04) and longer previous antiosteoporotic treatment (7.7±4.2 vs. 5.5±5.2years, p=0.043). No significant differences were observed in age, baseline BTM or bone formation/resorption index, and 25-OHD levels between patients with or without IR. IR patients presented worse BMD evolution in lumbar spine and femur at 18/24 months (Lumbar BMD: -2.8±4.2% vs.11.5±8.1%, p<0.001; total femur -0.6±2.2% vs.3.9±7.9%, p<0.001). No significant differences were observed in BTM changes throughout the study or in the evolution of their normalised bone formation/resorption index. 25-OHD levels and the incidence of new fractures were similar in both groups throughout the study.
Conclusion: In patients with severe osteoporosis, baseline BMD values and duration of antiosteoporotic therapy seem to influence the response to osteoanabolic agents.
Disclosure: The authors declared no competing interests.