The object of the proposed project is to assess the feasibility and cost-effectiveness of a trial to estimate the long-term efficacy of bisphosphonate treatment in preventing osteoporotic fracture. Such a trial is needed because the long-term effects of bisphosphonates are unknown: most randomised controlled trials were of less than 5 years' duration. Recent cost-effectiveness analyses undertaken for NICE assumed a 5-year treatment period with some residual benefit after treatment has been discontinued. However, as current guidance does not impose a limit on the duration of bisphosphonate treatment, clinicians may view this therapy as life-long. This approach has two disadvantages: it foregoes any possible residual benefit which would essentially be received without further cost and, potentially more importantly, it does not take account of concerns that, because of their mechanism of action, lengthy treatment with bisphosphonates may leave an individual with a weakened bone structure.

The proposed project will calculate the numbers of patients that would need to be recruited to each arm of the trial to detect surmised reductions in fracture rates, at proposed power levels. If the numbers are such that they may feasibly be recruited, the estimated expected value of the information garnered from the trial will be calculated and compared with the estimated costs of running the trial in order to determine whether it would be cost-effective to undertake the trial.