Discussion
This budget impact analysis is the first to apply UK data collected in a real-world setting to estimate the impact of widespread adoption of the FreeStyle Libre system from an NHS budget holder’s perspective. The results are therefore relevant to current decision making for UK local budget holders.
The ABCD nationwide audit demonstrates that the FreeStyle Libre system use is associated with improved outcomes, resulting in reduced diabetes-related resource utilization in T1 DM populations in the real world. This finding is consistent with other real-world studies that report reduced hospitalizations,16 17 24–26 improved HbA1c16 18 or improved quality of life or well-being14 16–18 associated with FreeStyle Libre system. Applying these data in a budget impact analysis, it was found that higher acquisition costs are partially offset by healthcare costs avoided. In an average-sized local English health economy (population size of 1790 T1DM), increasing FreeStyle Libre system uptake from 30% in year 1 to 50% in year 2 increased costs by 3.4%. Similarly increasing the FreeStyle Libre system uptake to 70% in year 3 increased the budget by a further 3.3%.
This increase in costs is associated with patient and healthcare system benefits including improved glucose monitoring, reduced hospital admissions and improved quality of life. FreeStyle Libre system use is associated with improved quality of life as reported in a time trade-off study,20 which reported a mean difference in health states of 0.03 (±0.053) between sensor-based (flash glucose monitoring) and conventional monitoring. This gain is assumed to reflect the greater convenience as well as intangible benefits of empowering patients to monitor and self-manage their glucose levels compared with SMBG. In addition, further quality of life improvements with FreeStyle Libre system compared with SMBG alone are expected, due to reduced risk of SHE27 and DKA events28 and improved HbA1c.29 Other benefits of FreeStyle Libre system not captured in this analysis include access to glucose management indicators that can be used as a substitute for quarterly HbA1c blood tests, further reducing system costs as well as the function to facilitate remote consultation and monitoring of people with diabetes. This feature has been particularly beneficial during the global COVID-19 pandemic.30–32
The findings of this analysis should be considered in the context of the following limitations. As with all budget impact analyses, there is uncertainty in the assumptions applied to project future uptake of the new intervention. The only RCT that has evaluated FreeStyle Libre system use in T1DM (IMPACT)6 did not observe statistically significant differences in HbA1c reduction, and thus the effects observed in real world settings cannot be definitively said to be a result of FreeStyle Libre system use. However, the primary outcome of IMPACT6 was to measure change in hypoglycemia, and this study only recruited people with a baseline HbA1c of 7.5% and under, therefore a change in HbA1c was not expected. The ABCD audit demonstrated that people with T1DM with baseline HbA1c of over 8.5% had a mean reduction in HbA1c of 1.2% compared with 0.5% in the overall T1DM population. This is consistent with other real world studies, demonstrating improved HbA1c pre and post starting FreeStyle Libre system.10 11
An assumption implicit in this cost analysis is that the change in resource utilization reported in the ABCD audit is transferrable to all T1DM populations that may switch to the FreeStyle Libre system in the future. However, the people included in the ABCD audit are a subgroup of all T1DM populations defined by the NHS funding criteria and those able to self-fund.19 These criteria, which include high testing frequency or hypoglycemia unawareness, may influence baseline characteristics and therefore resource utilization. However, although this has the potential to bias the analysis, it is not clear in which direction. The substantial reduction in HbA1c seen in the earliest cohort enrolled in the ABCD audit may be partly influenced by a ‘regression to the mean’ effect, as the HbA1c level at baseline was 8.3%. Unpublished data provided by a national specialty advisor for diabetes with NHS England suggests that these data are reasonably representative because at the time of this analysis, approximately 40% of people with T1DM living in the UK were using the FreeStyle Libre system. If later adopters have lower baseline HbA1c, similar to those recruited to IMPACT,6 they may not experience the same decrease in HbA1c or reduction in hospital events. Similarly, the baseline rate of DKA events and SHEs requiring hospital admissions was found to be between 5% and 10%. These rates may be high compared with the total T1DM population because people with a history of hospital admission for diabetes related events were prioritized for starting FreeStyle Libre system. Nonetheless, these rates are comparable with other real-world studies. The UK hypoglycemia study33 reported 1.1 and 3.2 episodes of SHE per person-year among people with T1DM for less than 5 years and between 5 and 15 years, respectively, and Heller et al34 reported that 5% of SHE in T1DM populations resulted in hospital stay.
Furthermore, 7-month data were prorated to estimate the annual outcomes post-FreeStyle Libre system use to capture outcomes from a larger sample. This was not expected to introduce a seasonal bias because recruitment was ongoing, and therefore, people were started and followed up at difference times of the year. Furthermore, comparison of the data applied in this analysis with 7-month data extracted at a different time point15 show similar trends.
There is also uncertainty regarding the attribution of a cost reduction to change in HbA1c because healthcare costs were not directly measured in the ABCD audit. The cost reduction assumption was sourced from a prior cost-effectiveness analysis23 using the previously validated CORE diabetes economic model in a UK context and therefore carries with it the uncertainty associated with that model. Furthermore, the cohort modelled in this modelling study may differ from the ABCD audit participants considered in this cost analysis. However, the cost attributed to a 1% reduction in HbA1c reported in Baxter et al19 was stratified by baseline HbA1c and matched to the baseline rate in the participants in the ABCD audit. The costs for the first 5-year period reported were annualized to a 1 -year basis. If the 5-year costs were weighted towards year 5 more than year 1, this assumption would have overestimated the short-term (1 year) impact. However, this potential cost-saving would be expected to be realized over the medium term (5 years).
The effect of uncertainty in our analysis was explored in one-way sensitivity analysis and threshold analysis that concluded that the results were most sensitive to the cost and number per day of SMBG tests in the SMBG arm. A range of plausible hypothetical uptake scenarios were therefore considered, including applying conservative scenarios for SMBG tests per. Furthermore, subgroup analysis found that the potential costs avoided with the FreeStyle Libre system may be higher among those with a higher baseline HbA1c. The difference in cost per patient were even lower in this group compared with the overall population.
This analysis did not compare the FreeStyle Libre system to traditional CGM or conduct cost utility analysis. The aqusition cost of FreeStyle Libre system of £937 per patient per year (PPPY) applied in this analysis are considerably lower than the acquisition cost of Dexcom G6 (£1850 PPPY) applied in recent cost utility analysis of traditional CGM conducted from a UK payer perspective.13 While the original FreeStyle Libre system differs from traditional CGM because it does not have alarms, the FreeStyle Libre 2 system, the next-generation device, was launched in late 2020 and has the added benefit of optional alarms. This therefore has the potential to provide similar functionality as other traditional CGMs in respect to triggering a patient response when glucose levels go too low or too high.
Conclusion
Widespread adoption of FreeStyle Libre system in T1DM populations offers many benefits and has a relatively small budget impact compared with the total cost of glucose management to health economies in the UK. People with T1DM and healthcare systems stand to benefit from the improved glycemic control, reduced diabetes related distress, reduced hospital admissions and the opportunity of virtual reviews that this easy to use monitoring solution provides.