OBJECTIVES:

10 years ago, NICE DSU Technical Support Document 14 noted the underutilization of piecewise models as an alternative to fully parametric models for survival extrapolations and recommended their consideration where more flexible survival models are required. This study aimed to review the adoption of the piecewise approach in recent assessments of oncology drugs submitted to the National Institute for Health and Care Excellence (NICE).

METHODS:

The survival extrapolation methods used in the 20 most recent oncology submissions to NICE (as of December 10^th 2021) were reviewed. For each appraisal, a pre-formatted extraction grid was used to capture detailed information regarding: whether the submitting manufacturer considered piecewise models and used these in their survival analyses; rationale for the manufacturer’s approach; and the responses from the Evidence Review Group (ERG) and the NICE Committee. Qualitative and quantitative analysis was conducted in order to understand utilization rates of piecewise models, rationale for their use and learnings for methodological implementation.

RESULTS:

Submitting manufacturers discussed piecewise models in 13/20 (65%) of the appraisals; in 8/13 (62%), the manufacturers used piecewise models in their base-case analysis. The ERG agreed with the use of piecewise models in 7/8 (87.5%) appraisals. In the appraisal where the ERG disagreed this was related to small sample sizes reducing statistical power for the piecewise approach. Assessment of visual fit and clinical plausibility were the most common justifications for a piecewise approach and were well-accepted by ERGs; ERG concerns most commonly centered on the timepoint chosen for the cut-point between the Kaplan-Meier curve and the start of extrapolation.

CONCLUSIONS:

Piecewise modelling is seeing frequent usage by manufacturers submitting to NICE in recent oncology appraisals and is well accepted with broad consistency in the justifications for its use. Careful consideration of the selected cut-point(s) is warranted due to the focus placed on this in critical review.