3 Evidence

This section summarises the evidence assessed in the original guidance for iFuse. All studies evaluated iFuse with titanium plasma spray coated implants. There is now evidence on iFuse-3D which suggests it may be clinically equivalent to the original iFuse implant. For more on this new evidence see the evidence review report. [2022]

Summary of clinical evidence


The evidence for iFuse considered by the external assessment centre (EAC) came from 12 studies:

  • 2 randomised controlled trials (n=251), Dengler et al. (2017b) and Polly et al. (2016a)

  • 2 comparative studies

  • 8 non-comparative studies.

    Both randomised controlled trials compared iFuse with non-surgical management. In Dengler et al. (2017b), non-surgical management was analgesic therapy, physiotherapy and cognitive behavioural therapy; in Polly et al. (2016a), it was analgesic therapy, physiotherapy, steroid joint injections and radiofrequency ablation. Follow‑up in the randomised controlled trials was relatively short (12 and 24 months), but in 1 comparative study, follow‑up was 6 years after implanting iFuse. One study compared revision rates for iFuse with those for open surgery (Spain and Holt 2017). The company sponsored 9 of the 12 included studies, and in each sponsored study at least 1 author was a company employee. For full details of the clinical evidence, see section 2 of the assessment report.

EAC conclusions on the clinical evidence


The EAC concluded that the evidence shows that iFuse improves pain, improves health-related quality of life and reduces disability compared with non-surgical management. The EAC noted that the definition of non‑surgical management differed between studies, but that it always included interventions that are representative of those used in the NHS for chronic sacroiliac joint pain. The EAC concluded that the evidence presented a reasonable estimate of the treatment effect of iFuse that was relevant to the population, intervention, comparators and outcomes detailed in the scope.

Summary of economic evidence


Neither the company nor the EAC identified any published economic evidence relevant to the decision problem. The company submitted 2 cost models, 1 comparing iFuse with open surgery and the other comparing iFuse with non-surgical management. Non-surgical management comprised a treatment pathway of analgesic medication, steroid joint injections and radiofrequency ablation. The assumptions and inputs of both models were based on clinical advice and UK pricing data, and both models used a 7‑year time horizon. The EAC made some changes to the parameters and inputs of the company model. This included correcting errors and updating inputs and assumptions. For full details of the economic evidence and the EAC changes to the model, see section 3 of the assessment report.

EAC analysis of the economic evidence


In its assessment report, the EAC concluded that the model comparing iFuse with non-surgical management was most relevant to NHS practice. The revised model showed that after 7 years, iFuse was cost incurring by about £560 per patient because of the higher initial costs (including acquisition and procedure costs). The EAC also noted that as time passes, the costs associated with non-surgical management continue to be accrued, whereas for iFuse most of the costs are upfront. It judged this to be relevant to the cost consequences because lifelong management is normally needed for chronic sacroiliac joint pain and people are likely to have iFuse in place for the rest of their lives. The EAC therefore considered that cost savings with iFuse were plausible beyond the time horizon of the company's model.


The EAC extended the time horizon of the model to simulate the costs for lifelong management of chronic sacroiliac joint pain. The company also lowered the price of iFuse consumables at consultation stage from £275 to £136. Using this longer time horizon and lower consumable price, iFuse saves £129 per patient at 8 years, after which the savings continue to increase.


For the guidance review, the EAC revised the model to reflect 2022 costs. Costs for iFuse were calculated separately for titanium plasma spray coated implants and 3D-printed implants. Details of the parameter changes are in the EAC costing update report. Results for the 2022 updated model shows iFuse is cost incurring up to 8 years (by £323) but becomes cost saving from year 9 (by £230.37) onwards. When using the cost of the iFuse-3D implant, it becomes cost saving from year 10 (by £172.31) onwards. [2022]

  • National Institute for Health and Care Excellence (NICE)