It is pretty much as it sounds -- plot some measure of health against effective wealth of a person and broadly speaking you will probably see a trend. Incidence rates of heart disease would be an example of it but not the whole story.
Is this an essay type question or just a one shot type thing?
For an essay you might wish to discuss the various metrics you might use -- is total lifetime against wealth a useful thing? What about life time from diagnosis/percentage alive at X years? Percentage diagnosis among groups -- it is well documented that a poor diet and/or smoking will mess you up, guess which things are more common among the poorer members of society these days? I mentioned lifetime before, this is not bad but quality of life is better (you can be kept ticking for a while but if you are not able to do much other than tick along then is it worth it)? Likewise they say life in the middle ages was short and brutal and have stats like average age was low 30s or something, this is fine until you consider that those that actually made it to 20 saw a decent chance of then making 50 or 60 -- high infant mortality does rather skew averages.
You might also wish to consider what goes for countries with free or effectively free healthcare. Hospital stays are very expensive, here is costs me nothing except lost wages (and possibly not even that) but if I did not have insurance in the US of 10 years ago I would be screwed, similarly I saw many in the US living with fairly crippling illnesses because they might not be able to afford treatment or even diagnosis ("oh he is just a bit ill" can very quickly become "oh he has been confirmed to have something nasty, good thing he has now has no job so he can focus on getting better"). Has this cheap and mandatory health insurance lark in the US changed anything or is it too early to tell?
Is there a drop off after a point for effective wealth? If I can afford to eat right and buy some decent insurance without too much hassle then does it matter if I am just in the low end of the higher tax bracket or have a far higher income? At the same time you never meet an old/retired bank manager.
Consider somewhere like China or India. In my lifetime their wealth has increased dramatically, there are a few nice ted talks showing what went with average lifetime.
http://www.ted.com/talks/hans_rosling_reveals_new_insights_on_poverty would be one of the
Do kids change anything? It costs a fortune to raise a kid, let alone multiple ones, and doing as such will reduce your effective wealth. Or does it provide some incentive to not be a fat bastard and take better care of yourself?
http://www.telegraph.co.uk/news/uknews/11360819/Average-cost-of-raising-a-child-in-UK-230000.html
http://money.cnn.com/2014/08/18/pf/child-cost/
US and UK there, in both cases the cost of a child is about that of purchasing a house and typically done over a similar period of time. Or if you prefer then done over the 20 years then if you earn 40K then two kids might well half that. 40K in the UK is a very respectable wage as well, lower income type wages tend to be 25K or somewhat lower (full time minimum wage
https://www.gov.uk/national-minimum-wage-rates gets you around £14000 a year).
Even within the same country what buys me a shorter lease on a one bedroom flat in London buys me a mansion in rural Yorkshire. Do you wish to account for this in your measure of effective wealth?
and because I feel nice here is a very nice source you can use for this
http://www.who.int/mediacentre/factsheets/fs310/en/index1.html
The following youtube channel has some good stuff as well, not all of it is relevant to what you want but a lot of it is
https://www.youtube.com/user/thehealthcaretriage/videos