This study recruited 4,538 women aged 60 to 85 years old. Inclusion criteria were a T-score bone mineral density (BMD) of -2.5 at the hip or -2.0 at the spine with radiological evidence of a spinal fracture.
Patients were randomised to treatment with placebo or 1.25mg of tibolone daily (Note the usual dose is 2.5mg daily). Data were collected for fractures, radiological fractures, cardiovascular events and cancers.
The study was stopped early due to an increased risk of stroke being detected in the active treatment arm. The median treatment period was 34 months, in this time other outcomes were as follows:
- Reduced risk of vertebral fracture (Relative risk reduction 0.55; 95% CI 0.41-0.74; P<0.001)
- Reduced risk of non-vertebral fracture (RRR 0.74; 95% CI 0.58-0.93; P=0.01)
- Reduced risk of invasive breast cancer (RRR 0.32; 95% CI 0.13-0.80; P=0.02)
- Reduced risk of colon cancer (RRR 0.31; 95% CI 0.10-0.96; P=0.04)
- Increased risk of stroke (RRI 2.19; 95% CI 1.14-4.23; P=0.02)
Despite the apparent benefits in terms of reduced fractures and cancers the additional risk of stroke appears to be the over-riding concern. The current licence for tibolone includes second-line prophylaxis of osteoporosis in patients who are intolerant of, or contraindicated for, other treatments for osteoporosis.
Action: Tibolone should not be used as a treatment of choice for osteoporosis or fracture prevention. Patients intolerant or contraindicated to other other treatment options should have the stroke risk explained if considering this treatment.