Our approach to measuring Social Value

At Westfield Health, we believe in measuring the true impact of our services. To do this accurately, we use the Wellbeing-Adjusted Life Year (WELLBY) methodology, which is recognised as the gold standard for social cost-benefit analysis in the UK.

Guided by the HM Treasury Green Book, this approach allows us to look beyond just the financial cost of a health cash plan claim and measure the actual improvement it makes in a person’s wellbeing. This way we establish a consistent financial benchmark that can be compared with other public and private sector initiatives.

How we value wellbeing

Our methodology is rooted in data on subjective wellbeing, utilising a standard 0–10 scale for life satisfaction – a globally recognised measure. When a person experiences a health-related change, such as relief from pain or alleviation of anxiety, their life satisfaction score changes.

A 1-point change in life satisfaction that lasts for one year for one person equals one WELLBY – valued at £13,000 in 2019 by economic experts drawing on extensive long-term datasets. For our calculations, we have used an adjusted figure of £15,300 for one WELLBY in 2026 to account for inflation.

Our impact

Different types of care impact wellbeing in different ways, and changes in life satisfaction are widely variable according to type. For example, improved mental health’ is worth two WELLBYs.

We categorise our claims into four main groups to accurately reflect these nuances and assign WELLBY values according to both established and estimated life satisfaction changes for different interventions.

  1. Clinical treatment, e.g., surgery, physiotherapy, counselling. These treatments are highly transformative, moving a patient from illness to better health. While the NHS also provides these services, our primary value lies in reducing waiting times and enabling early intervention.
  2. Symptom relief, e.g., alternative therapies. These services play a vital supportive role by relieving symptoms and preventing further health declines. They hold distinct value as they are frequently restricted or unavailable on the NHS.
  3. Preventative care, e.g., health screenings, optical and dental check-ups. These interventions provide peace of mind and early detection. Because general health screenings are rarely offered to healthy individuals via the NHS, our plans are often the primary trigger for people to take proactive health measures.
  4. Financial security, e.g., prescription charges, hospital benefits. These benefits directly remove the financial distress associated with illness. Because things like private hospital stays and prescriptions are not free on the NHS, our plans provide a unique and highly direct benefit.

Ensuring accurate and responsible reporting

To ensure that our figures are robust and to prevent any overstatement of our impact, we take a highly conservative approach and have adjusted our calculations based on three key principles of Social Value accounting:

  • Deadweight. We calculate the portion of a health outcome that would have naturally occurred naturally or through the NHS without someone having access to our health cash plan. By subtracting this from our total impact, we isolate the specific, additional wellbeing benefits that our private health insurance and cash plans deliver.
  • Attribution. We only factor in the specific portion of the claim value that we pay out, ensuring our reported value directly mirrors our financial contribution. Corporate claims generally see a slightly higher attribution rate that consumer claims.
  • Duration. We always use the lowest values in available data ranges and conservatively assume that the wellbeing benefits of our health cash plan claims last for only one year, even for treatments like surgeries that often provide multi-year benefits.

Creating savings for the NHS

While our social value reporting measures the human impact on individual lives, our fiscal savings model measures our systemic impact on the public purse. By facilitating private access to medical services, Westfield Health actively reduces the operational and financial burden on the NHS.

We calculate this using an ‘avoided cost’ principle. For every claim we pay, we identify the equivalent service that the patient would have otherwise needed to access through the NHS. We then apply a precise value to these claims based on official NHS unit costs, allowing us to clearly demonstrate the direct financial pressure we alleviate from the public healthcare system.

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