In Massachusetts, the Behavioral Risk Factor Surveillance Study (BRFSS) has asked the adults it interviews "Do you consider yourself to be transgender?", and a whole lot of demographic and health-related questions.
Many studies in the past have sought out a transgender population to try to say something about the health of the group, but this is the first one to rely on a "random" sample, meaning calling people up at random; and that's probably the best way to be sure that you've got a study population that is fairly representative (at least of people with phones).
In addition to addressing trans health from a population perspective for the first time, this study is also the first to report simple basic demographics of the transgender population in the US as well, including the most basic one - how many transgender people are there?
The answer, in this study, is about 1 in 200 in Massachusetts, about 1 in 110 in a similar study from Vermont, and 1 in 170 in Boston. It is likely (for reasons I've discussed before) that these are overestimates, meaning that the true proportion is probably somewhat lower than that, but how much lower? That's hard to guess, it depends on how many nontrans people answer the wrong way because they are distracted or misunderstood the question. The only way to figure that out is to call back the people who said they were trans and ask them again.
The study is very interesting in that it validates some things trans health activists have known for years, but there isn't strong evidence to support all the health disparities that have been identified from "convenience" samples. Members of the trans population in this Massachusetts study were less likely to be employed, and more likely to be living in poverty than the nontrans population. The study also documented that 36% of the trans population were smokers, compared to 17% of the nontrans population. But markers of access to health care were not particularly different. The trans population was less quite a bit less likely to have health insurance (86%) than the nontrans population (94%), but this did not translate into not having a regular health care provider or not seeing a doctor because they couldn't afford it, and the trans population was even more likely to have had a checkup in the last 12 months (85%) than the nontrans population (75%).
Mental health measures did show some substantive differences: 70% of the trans population reported usually or always getting needed emotional support, but this was quite a bit lower than the 90% of nontrans people who got their emotional needs met; and 14% of the trans population reported being dissatisfied with their life, but only 6% of the nontrans population did.
The authors were very thoughtful about ways that these results might be misleading - for instance that trans people are probably less likely to be stably housed and have a telephone, so these figures may well present a rosier picture than a fully representative sample of trans people would be. And also, not knowing how many cis-gender (nontransgender) folks inadvertently classified themselves as trans, it is hard to know the degree to which true differences between the trans and cis populations are diluted by these inaccurately coded folks. Another possible source of bias might be people who have transitioned, but no longer consider themselves to be transgendered, although I suspect this is pretty unlikely to be a substantial part of the population, because the way the question in Massachusetts was asked, they made it clear that they meant "experience(d) a different gender identity from their sex at birth. For example, a person born into a male body, but who feels female or lives as a woman". But excluding people who no longer consider themselves to be trans would, probably, make the differences seem larger than they actually are. A similar bias would arise from trans people not feeling comfortable describing themselves as trans to a stranger on the phone.
Thanks Gunner & Stewart!