Table 5 Attribution, deadweight, displacement and drop-off

Attribution

Attribution was calculated by estimating units for each valued outcome per patient (informed by the impact map), stakeholders were involved in these calculations, and provided expertise in estimating, for example, how many unnecessary emergency room presentations could be avoided for a patient with lung cancer over a five period if they were receiving quality supportive cancer care [11, 31] Values were then calculated on a per unit basis, per capita over a one-year period, and a five-year period.

Deadweight

Deadweight was calculated as a percentage of the outcome that could have occurred if the patient had not received any supportive care, this percentage of the monetary value was then deducted from each value for each year (after the first year of implementing supportive cancer care) [31]

Displacement

Displacement was considered in the SROI but as the alternative to supportive care, in the context of the forecast was no supportive care, and factors displacing outcomes in the SROI would likely include treatment effects for patients, and the natural history of lung cancer disease, it was not possible to accurately apply an adjustment for this.

Drop-off

Finally, drop-off was calculated as a percentage of the outcome that would reduce in value over time. This estimation was informed by the extent of variability in an outcome based on individual patient characteristics, and disease trajectory over a one-year and five-year period. For outcomes where variability was known to be high (based on stakeholder views and the evidence), a 50% drop-off rate was applied. Where variability was likely but known not to be high, a 20% drop-off rate was applied. For all other patient outcomes, a 10% drop-off rate was applied. Healthcare system cost savings were excluded from drop-off rates because they were absolute values and discounting process captured effects of inflation.