Yesterday a paper I co-authored was published in the British Medical Journal. The paper, available free of charge at the BMJ website, analyzes mortality among Japanese working age males between 1980 and 2005 and estimates the changes that occurred after the collapse of the bubble economy. Our main findings were that a previously existing inequality in health between professional/managerial workers and the remainder of the population was reversed in the 10 years after the economic collapse. This reversal happened not because the health of non-professionals improved, but because professional and managerial workers saw a rapid increase in mortality.

Before 1990 there was a fairly clear pattern amongst the main causes of mortality in Japanese men: the managerial and professional occupations had lower mortality rates. Mortality rates for all groups were largely declining over time, and at roughly the same rate, but managerial and professional occupations on the whole had lower mortality rates. However, after the collapse mortality rates in these two groups suddenly began to increase, while those amongst the non-professional categories largely maintained their previous trajectory. These trajectories and the changes can be seen easily in Figure 1 of the paper, and the changes that occurred at the time of the collapse are summarized in Table 4. For example, before 1995 the relative risk of all cause mortality in managers/professionals was 0.70 (i.e. 70% of that in the other occupations). After 1995 it was 1.18, about 20% higher (and this difference was statistically significant). Table 4 shows that while before 1995 managers/professionals had lower mortality across almost all the major causes of mortality, after 1995 this relationship disappeared or was reversed.

As an aside, the paper also shows that massive increases in suicide rates in all professions coincided with the economic collapse of the late 80s/early 90s.

There is a possibility that so-called “numerator-denominator bias” might have affected the results: if people registered their employment status differently on their death certificate (the numerator) to the population census (the denominator), we might over-estimate the effect of the stagnation in those occupation groups (like managers) that shrank fastest at that time. This effect might be possible if, for example, after the economic collapse managers and professionals moved into other professions or became unempoyed, but after they died their family recorded their profession on their birth certificate as that which occupied the majority of their career. However we checked carefully for this and confirmed that even the most extreme possible effect of numerator-denominator bias doesn’t change the essence of the results, only the magnitude.

It’s dangerous to ascribe reasons and causal relationships to these kinds of phenomena, but the strong implication is that there is a relationship between the economic aftermath of the collapse and this reversal in health inequality in Japan. We postulate that this might be due to the rapid shrinking of the size of the managerial/professional workforce and changes in its working conditions that did not affect the labour/service industries as much. Other possibilities include changes in insurance status and access to healthcare, or perhaps some kind of health-system effect on cancer survival. It’s probably not due to unemployment: unemployment is categorized separately in the labour market statistics and death certificates, so theoretically a person who is sacked in 1985 and dies in 1990 should be counted as an unemployed person, and since we checked for numerator-denominator bias we think we ruled this out.

Japan has very different patterns of mortality to other developed nations, but this paper gives us an indication of the possible large effects that an economic downturn and subsequent stagnation can have on population health. It also shows that an economic downturn doesn’t necessarily affect everyone equally, and doesn’t necessarily affect the poor, or non-professional occupations, more than it does the rich. I guess the results of this paper and its lessons about the role downturn and stagnation can play in health may be applicable to countries like the UK and USA, which are just beginning to experience what Japan did in the 1990s. This paper suggests that we should expect significant effects of the downturn on health, but that we shouldn’t assume it will hit the poorest hardest, and should be aware that every nation’s post-depression experience may follow a unique trajectory. It also tells us that significant health gains made over a long period of time, such as are seen in this data, can be reversed rapidly after a major economic downturn, and economic collapse can undo 20 or 30 years of health gains. In health terms, major economic events are certainly not to be sniffed at!