The recent report from NICE's Citizen's Council has got some media traction for its support of offering material incentives for healthy or healthier behaviour.

There were important, populist-placating caveats, of course. The report specifies that "incentives should never be exchangeable for tobacco or alcohol; are only offered to people who are committed to changing their health behaviours; cash incentives should be only offered as a last resort; the progress of participants is monitored throughout; and the results of the schemes are analysed so that more can be learnt about their effectiveness".

It's one of those things that instinctively sounds like a good idea. Quickly, you mentally rehearse the political syllogism from 'Yes, Minister' (Something must be done ... this is something ... therefore this must be done").

Limitedly, you also think, 'could the incentive be cheaper than treatment?' (forgetting that to spend public money thus, you just might have to assess whether people are actually complying, which of course means a new bureaucracy - hurrah!).

But does it work?

Not according to the Cochrane Collaborative's 2008 review of incentive schemes for stopping smoking, Its review of 17 studies found that "none of the studies demonstrated significantly higher quit rates for the incentives group than for the control group beyond the six-month assessment. There was no clear evidence that participants who committed their own money to the programme did better than those who did not, or that different types of incentives were more or less effective. There is some evidence that although cessation rates have not been shown to differ significantly, recruitment rates can be improved by rewarding participation, which may be expected to deliver higher absolute numbers of successful quitters".

The authors concluded that "incentives and competitions have not been shown to enhance long-term cessation rates, with early success tending to dissipate when the rewards are no longer offered. Rewarding participation and compliance in contests and cessation programmes may have more potential to deliver higher absolute numbers of quitters".

That is one review (a high-quality one, mind) of one aspect of health improvement - an area where getting the government to ban things has already made massive difference. But it makes a serious point.

Affecting and sustaining changes in population health behaviour is hard. It would be nice if there were short-cuts.

'Nudge' theories may be fashionable, but they are recent arrivals and the evidence for their use in health policy is not fantastic. In the great phrase of James Oberg, NASA engineer and science writer, “you must keep an open mind, but not so open that your brains fall out”.