The hazard ratio (HR) is a commonly used summary statistic when comparing time to event (TTE) data between trial arms, but assumes the presence of proportional hazards (PH). Non-proportional hazards (NPH) are increasingly common in NICE technology appraisals (TAs) due to an abundance of novel cancer treatments, which have differing mechanisms of action compared with traditional chemotherapies. The goal of this study is to understand how pharmaceutical companies, evidence review groups (ERGs) and appraisal committees (ACs) test for PH and report clinical effectiveness in the context of NPH.

A thematic analysis of NICE TAs concerning novel cancer treatments published between 1 January 2020 and 31 December 2021 was undertaken. Data on PH testing and clinical effectiveness reporting for overall survival (OS) and progression-free survival (PFS) were obtained from company submissions, ERG reports, and final appraisal determinations (FADs).

NPH were present for OS or PFS in 28/40 appraisals, with log-cumulative hazard plots the most common testing methodology (40/40), supplemented by Schoenfeld residuals (20/40) and/or other statistical methods (6/40). In the context of NPH, the HR was ubiquitously reported by companies, inconsistently critiqued by ERGs (10/28), and commonly reported in FADs (23/28).

There is inconsistency in PH testing methodology used in TAs. ERGs are inconsistent in critiquing use of the HR in the context of NPH, and even when critiqued it remains a commonly reported outcome measure in FADs. Other measures of clinical effectiveness should be considered, along with guidance on clinical effectiveness reporting when NPH are present.