Thursday, February 27, 2020

The Rise: Sex Ratio Trend


The Rise: Sex Ratio Trend


Note: this is part of the Youth Suicide Rise project.


We have seen that suicide rates have increased proportionally more for girls than for boys since 2007.  Let us now look at the suicide rates sex ratio trend since 1999:



We see that 2007 was an anomaly but that there was indeed a steady decline between 2010 and 2016 in the ratio of suicides between teen boys and girls -- however, this trend is merely a continuation of a trend that started before 2007 and goes back to at least the beginning of the millennium.

To see an even longer trend, we have to combine ICD-9 and ICD-10 data for age 10-19 groups:


The graph indicates that the sex ratio of teen suicides has been generally declining since the mid-1990s (polynomial trend) or at least since the start of the millennium (5-year averages).

Since child suicides are dominated by the oldest kids, and the previous data included adult teens, we should examine 'tween' children (age 10-14) separately:


Once again we see the downward trend since 2007 is merely a continuation of a previous trend, and actually appears to be slowing down.

Since the tween group suicides are mostly due to deaths at age 14, let us finally look at age 12 and 13:



This graph should be interpreted with caution, since some death counts for girls were at times below 20 in the early millennium years, and we can see the ratio is fairly volatile.  Once again, however, the data fails to support the notion that, even at the ultimate 'tween' age 12-13, the sex ratio trend has changed much since around 2007.

To summarize:  there is a long-term 'closing gap' trend of declining ratios between suicides by boys and girls, and this trend has not significantly accelerated during the recent child suicide rise period.

What changed is essentially this: between mid-1990s and mid-2000s, suicide rates have been mostly decreasing faster for boys than for girls, and since 2007 suicide rates have been mostly increasing  slower for boys than for girls.

The simplest model is that since mid 1990s the same factors have been slowly lowering --  modulo strong fluctuations -- the sex ratio of child suicides, and this is why suicide rates have been rising faster among girls than among boys recently.


Technical Note:


The CDC WISQARS tool does not always display age-adjusted rates, so we looked only at age 13-17 (instead of 0-17) to lessen possible effects of shifting age demographics.

The 5-year moving average green line values are set at endpoints, and so the start of any downward trend implicates the previous 5-year period.


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