ACE: Economic Evaluation of the Proactive Lung Cluster

This chapter reports on economic evaluation in relation to the proactive lung ACE projects by the Department of Health's Policy Research Unit in Economic Evaluation of Health and Care Interventions (EEPRU). Economic evaluation is concerned with the estimation of the total impact of a specific intervention on population health. Evaluations are structured through the estimation of the short- and long-term incremental cost and health implications (often measured in terms of life-years or quality adjusted life-years (QALYs)) of an intervention, contrasted against other potential management options for the same patients.

A new intervention that is found to be more effective, in terms of population health, than all relevant current alternatives must additionally be evaluated against its incremental cost implications, i.e. how much more or less it costs the NHS than its comparators. A new intervention, found to both increase population health and decrease total costs to the NHS, is said to dominate its comparators and is considered to be a worthwhile investment. In contrast, an intervention which increases both health and total costs must be considered against the health benefits of services which could have otherwise been funded, the opportunity cost of the intervention. This comparison is made through the consideration of the incremental cost effectiveness ratio (ICER) of the intervention (the additional total cost to the NHS per gain in health) compared to the cost-effectiveness ‘threshold’. This ‘threshold’ has set between £20,000/QALY and £30,000/QALY based on NICE’s guidance, [1] but this ‘decision rule’ is likely to incorporates more than just opportunity cost (e.g. the value of innovation). Recently health opportunity cost in the NHS has been estimated at approximately £13,000 per QALY (i.e. approximately 77 QALYs forgone per £1,000,000 additional cost of a new service or intervention).[2]

Recent UK research suggests that CT as a screening mechanism to detect lung cancers may be cost effective (the UK Lung Screening Trial, UKLS),[3] finding it to be associated with an incremental cost-effectiveness ratio (ICER) of around £8,500/QALY. The UKLS pilot trial considered the effectiveness of risk prediction modelling and low dose CT screening as a means of identify lung cancer at an earlier stage in high risk patients than symptomatic presentation. In the pilot, a target population was identified using NHS records and mail questionnaires and classified by their expected risk of developing lung cancer into the future (using the LLP risk algorithm). Only patients identified as being at high risk of lung cancer and eligible for the trial were invited into recruitment centres and for subsequent screening. By solely focussing on the identification of lung cancer, and doing so in a highly targeted manner, the UKLS arguably missed the potential to deliver a broader message of general respiratory health and to engage with many patients, who while not at high risk of lung cancer, may still have had the potential to have poor respiratory health and may benefit from proactive preventative interventions.

The ACE Proactive Lung cluster projects have sought to implement a broader intervention by combining targeted CT screening for patients at high risk of lung cancer, with face to face respiratory health consultations at which spirometry and brief smoking cessation advice and referrals are available as appropriate. Some of the projects have additionally had a community event component, seeking to improve the local community’s understanding of respiratory health and, as a secondary outcome, to improve uptake of the screening component. By including the respiratory health consultations element alongside the CT screening, the ACE projects have the potential to make and to report impact on a broader range of factors, including COPD diagnosis. Also to identify patients interested in smoking cessation advice, at a potentially lower marginal cost than if such activities were provided independently of screening which the UKLS has indicated is likely to be cost-effective as a standalone intervention. This evaluation will explore what factors could impact the cost-effectiveness of interventions such as those implemented in the ACE projects, and under what conditions an extended intervention, including respiratory health consultations for a wider pool of patients, would have the potential to be cost-effective.

Due to the design of the projects evaluated (primarily their limited size, period of follow up, and lack of robust control), an evaluation of the cost-effectiveness of the ACE projects themselves was not possible. The evaluation conducted here is designed to be illustrative only. The implications of this are that it is not possible directly to compare the effectiveness of the different project designs, nor to comment on the specific merits of each design. Therefore, this evaluation should be seen as primarily an attempt to inform the design - and importantly the evaluation - of future lung cancer screening projects; and to consider the scenarios under which the addition of a respiratory health consultation element to a lung cancer screening intervention may or may not be cost-effective.

Additionally, as the aim of the evaluation is to explore the potential cost-effectiveness of the different project designs should they be incorporated into routine NHS activity, the unit costs are representative of the additional cost burden the NHS would be expected to face from a marginal increase in activity, rather than the cost paid by the commissioner of the projects at the time of funding. This important distinction is most apparent in the consideration of the cost per CT conducted in a mobile CT van. The cost per scan paid by the commissioner during a small, local project would not be a fair indicator of the cost that would be expected if the service was rolled out nationally. As a result, the estimation of the cost of each project is broken into its constituent unit costs and resource use implications.

Of the four ACE proactive lung projects conducted (Nottingham, Liverpool, Manchester, and London), two shared sufficient data on the events observed in the projects to describe them in this report (Nottingham and Liverpool). As a result, this report provides an overview of the design of all four of the projects, but only considers the potential resource implications and health impacts of two of them.

To evaluate the potential impact of the ACE projects, the short-term direct cost to the NHS of each are considered alongside the long-term cost and population health outcomes. Short-term costs are defined here as the direct costs associated with the projects from initial community events and patient identification, to diagnosis of disease at the multi-disciplinary team (MDT). While all four projects are discussed and overviewed, only two of the projects (Liverpool and Nottingham) were able to provide detailed estimates of activity and effectiveness of the intervention, and as such are the only ones to be evaluated in any detail.