The government's announcement that it plans to review co-payments and whether they should be allowed in the NHS surprised me because it asks the wrong question.

Not because allowing top ups would be a victory for common sense in emotive cancer cases, or because it would formalise a system that already exists, or because the current restrictions are probably unlawful. Neither do I think the NHS universality argument holds tight - excluding people who choose to pay from the NHS also harms equitable care.

The real reason for my surprise came when I jotted down the key ingredients one might require to move from world class commissioning (assuming we get there) to a system where patients choose their primary care trust in a competitive health maintenance organisation-style model.

The interesting thing is not how you perceive such a model in terms of the NHS today - either viscerally against or encouraging market-leaning reform - but that we seem to be ticking off the list at quite a pace already. Take the defined benefits coverage set out in the NHS constitution, for example.

Commissioning tricks

The biggest hurdle will always be co-payments. Around 10 years ago in the US, the insurance industry and HMOs were attempting to use commissioning tricks being enacted here at the moment - controlling thresholds for referral, specifying approved networks of doctors or hospitals and altering the points of intervention in the disease cycle (providing there was a return on investment, which almost always meant prevention).

These skills may have cut costs, but they caused widespread disquiet about care purchasers.

Fundamentally, what drove these businesses was actuarial modelling around total cost. Understanding the likely duration of the plan, co-morbidity and claims behaviour was essential and drove impressive case and utilisation management programmes.

In the British way, we tried half-baked case management in 2003 and now are having a go at utilisation management. Actuarial modelling has not been popular in the NHS. Instead, we model around unplanned admissions, health inequality or service provision.

All laudable, but not very robust if you don't understand the total health cost or outcome.

Future choices

Granted, as these US systems grew in complexity, they put the emphasis on value-added healthcare in the wrong part of the system. Providers largely tooled up to protect bills. But the underlying point for me was the irritation in commissioning-style plans to patients, families and doctors. We're not talking about the uninsured here (separate problem) but those who perceive themselves to have paid up and expect to be treated. How did the US commissioning equivalents fix the problem of customer satisfaction? You guessed it, co-payments!

In the US commissioning era, a family taking a young child to the emergency room in the middle of the night got a terse call in the morning saying their plan didn't cover such unnecessary investigation and the bill would not be covered. They were reminded to get prior approval or see primary care in future. Could this be a parallel to world class commissioning plus?

What followed in the US was simple: coverage for defined benefits to ensure federal requirements, along with top-up payments for care outside these limits. So, in theory, people chose their plan provider and in the middle of the night they had a choice: phone the out-of-hours call centre with a triage option to be seen in a primary care centre or take their child to hospital, knowing the commissioner will pick up the core payment, and make up the difference themselves.

This leaves two choices: a choice of provider and of who commissions your care. So the right question for me is not whether we should introduce co-payment, because a narrow cancer drug review will not solve the problem of patient dissatisfaction. Rather, we should be asking what the core benefit is and whether a choice of commissioner is the future.