From Born to Love, page 245:
The pioneering research on social status and health was done in the United Kingdom, examining civil servants whose rank in the government bureaucracy is easy to track. Because Great Britain has national health insurance , the connection between social status and health there cannot be due primarily to lack of access to health care among the lower-ranking bureaucrats – all are cover by the same system, though the wealthy can add private insurance if they so desire. In this study, those on the bottom were not truly poor, simply working or lower middle class.
The “Whitehall Study” – and a second study that included female civil servants as well as males called “Whitehall II” – found a massive “social gradient” in health. This wasn’t just one correlation: it was a clear slope downward stepwise to worse health from top to bottom. The first Whitehall study – so called because this is the name of the headquarters of the British Civil Service – included eighteen thousand men. It found that at ages forty to sixty-four, the lowest ranking men were four times more likely to die from any cause than those who had reached the top of the greasy pole. The gradient directly tracked a man’s rank in the bureaucracy, so those of the second rank did better than those of the third, and the top rank was best of all.
Other studies – for example, those looking at a country’s population as a whole – have typically found a gradient where those at the bottom have twice to three times the mortality risk of those at the top. Studies that include women (like Whitehall II) tend to find interesting differences in status-related risk, where a woman’s health risks are more correlated with the overall income level in her household that with her own job status.