Clinical guideline 14616 provides recommendations for risk assessment for fragility fracture, including the use of DXA scans, and, therefore, we have not considered the services required to assess fragility fracture risk prior to offering treatment with bisphosphonates. We do not anticipate that any additional services would be required to offer oral bisphosphonate treatment to the population eligible for risk assessment within CG146 as these treatments are prescribed in primary care. Widespread use of zoledronic acid or i.v. ibandronic acid across the population eligible for risk assessment would be likely to result in the requirement for additional capacity in existing services to administer these treatments in secondary care.
We have conducted a simple budget impact analysis to estimate the potential impact on the NHS of changes to current prescribing patterns under certain assumptions. For the purposes of assessing the budget impact we have assumed that bisphosphonate treatment with weekly alendronic acid is offered to all patients who have a QFracture score of > 1.5%, but that uptake is gradual, with only one-fifth of the patients eligible for treatment starting treatment each year over the next 5 years. Alendronic acid has been chosen as it is neither the cheapest nor the most expensive oral bisphosphonate. The generic weekly alendronic acid preparation has been assumed to be prescribed in all patients as it is both the lowest cost and currently the most commonly prescribed treatment (see Table 1). A QFracture score of 1.5% has been chosen as the threshold for offering treatment as this was the lowest absolute risk at which the INB for any bisphosphonate compared with no treatment was positive when valuing a QALY at £20,000. The economic model simulates a population aged ≥ 30 years and selects from this population the cohort eligible for risk assessment. Therefore, it also provides an estimate of the proportion of the general population aged > 30 years who would be eligible for risk assessment. The model estimates that for every 100,000 patients who are eligible for risk assessment there are another 63,763 who are not eligible for risk assessment and, therefore, 61% of the general population are eligible. Combining this with information on the number of people aged > 30 years in England from the ONS (33.7 million)159 allows the calculation of the number of people eligible for risk assessment (20.6 million). From the characteristics of 200,000 simulated patients we have estimated that 61% of those eligible for risk assessment have a QFracture score of > 1.5%. We have assumed that the treatment duration is 6 months, as this was the treatment duration applied in the cost-effectiveness model for oral bisphosphonates based on observational data on the average persistence with treatment. Using these assumptions, the total undiscounted cost of treating the current prevalent population is estimated to be £95M over 5 years.
Data from the prescription cost analysis suggest that there are currently 8.3 million prescriptions per annum for oral bisphosphonate treatment in primary care, at an estimated cost of £10M per annum.38 For this cost estimate we applied the cost for generic preparations for each dose to make the figures comparable with those above, where generic prescribing was assumed. Over 5 years the undiscounted cost for oral bisphosphonate treatment at the current level of prescribing is estimated to be £50M.38
Therefore, we estimate that if all patients with a QFracture score of > 1.5% were prescribed oral bisphosphonates, this could double the current cost of bisphosphonate prescribing over the next 5 years. These estimates are provided to give an indication of the maximum cost of additional prescribing with costs likely to be lower if uptake is less than 100%. Costs would also be expected to fall once the prevalent population eligible for treatment have been treated as the numbers becoming eligible for treatment each year will be smaller than the current population who are eligible. Furthermore, some of those whom we have included in the eligible population will already have received bisphosphonate treatment, which would further reduce the numbers likely to initiate treatment in the next 5 years. Therefore, our estimates provide an upper ceiling on the expected costs.
