An Editorial in Nature this week highlights three studies of a sex bias in biomedical research.
And yet, despite the obvious relevance of these sex differences to experimental outcomes, three articles in this issue (see pages 688, 689 and 690) document that male research subjects continue to dominate biomedical studies. Some 5.5 male animal models are used for every female in neuroscience, for example. And apart from a few large, all-female projects, such as the Women's Health Study on how aspirin and vitamin E affect cardiovascular disease and cancer, women subjects remain seriously under-represented in clinical cohorts. This is despite reforms undertaken in the 1990s, when sex discrimination in human trials was first widely recognized as a problem.
This reminded me of something I wrote a little while back to explore part of the reason for this bias in research models. The post originally appeared December 2, 2008.
The titular quote came from one of my early, and highly formative, experiences on study section. In the course of discussing a revised application it emerged that the prior version of the application had included a sex comparison. The PI had chosen to delete that part of the design in the revised application, prompting one of the experienced members of the panel to ask, quite rhetorically, "Why do they always drop the females?"
I was reminded of this when reading over Dr. Isis' excellent post on the, shall we say less pernicious, ways that the course of science is slanted toward doing male-based research. Really, go read that post before you continue here, it is a fantastic description.
Thank you. That's the first time I've seen someone address the reasons behind ongoing gender disparities in health research. I still can't say as it thrills me (or you, obviously), but I understand a bit better now.
Did somebody ring?
As I pointed out explicitly at least once, research funding has a huge role in what science actually gets conducted. Huge. In my book this means that if one feels that an area of science is being systematically overlooked or minimized, one might want to take a close look at the manner by which science is funded and the way by which science careers are sustained as potential avenues for systematic remedy.
There are a couple of ways in which the generalized problems with NIH grant review lead to the rhetorical comment with which I opened the post. One very common StockCritique of NIH grant review is that of an "over ambitious" research plan. As nicely detailed in Isis' post, the inclusion of a sex comparison doubles the groups right off the bat but even more to the point, it requires the inclusion of various hormonal cycling considerations. This can be as simple as requiring female subjects to be assessed at multiple points of an estrous cycle. It can be considerably more complicated, often requiring gonadectomy (at various developmental timepoints) and hormonal replacement (with dose-response designs, please) including all of the appropriate control groups / observations. Novel hormonal antagonists? Whoops, the model is not "well established" and needs to be "compared to the standard gonadectomy models",
Grant reviewers prefer simplicityKeep in mind, if you will, that there is always a more fundamental comparison or question at the root of the project, such as "does this drug compound ameliorate cocaine addiction?" So all the gender comparisons, designs and groups need to be multiplied against the cocaine addiction/treatment conditions. Suppose it is one of those cocaine models that requires a month or more of training per group? Who is going to run all those animals ? How many operant boxes / hours are available? and at what cost? Trust me, the grant proposal is going to take fire for "scope of the project".
Another StockCritique to blame is "feasibility". Two points here really. First is the question of Preliminary Data- of course if you have to run more experimental conditions to establish that you might have a meritorious hypothesis, you are less likely to do it with a fixed amount of pilot/startup/leftover money. Better to work on preliminary data for two or three distinct applications over just one if you have the funds. Second aspect has to do with a given PIs experience with the models in question. More opportunity to say "The PI has no idea what s/he is doing methodologically" if s/he has no prior background with the experimental conditions, which are almost always the female-related ones. As we all know, it matters little that the hormonal assays or gonadectomy or whatever procedures have been published endlessly if you don't have direct evidence that you can do it. Of course, more latitude is extended to the more-experienced investigator....but then s/he is less likely to jump into gender-comparisons in a sustained way in contrast to a newly minted PI.
Then there are the various things under grantspersonship. You have limited space in a given type of grant application. The more groups and comparisons, the more you have to squeeze in with respect to basic designs, methods and the interpretation/alternative approaches part. So of course you leave big windows for critiques of "hasn't fully considered...." and "it is not entirely clear how the PI will do..." and "how the hypothesis will be evaluated has not been sufficiently detailed...".
Although research funding plays a huge role in career success, it is only part of the puzzle. Another critical factor is what we consider to be "great" or "exciting" science in our respective fields.
The little people can fill in the details. This is basically the approach of GlamourMagz science. (This is a paraphrase of something the most successful GlamourMagz PI I know actually says.) Cool, fast and hot is not compatible with the metastasizing of experimental conditions that is an inevitable feature of gender-comparison science. Trouble is, this approach tends to trickle down in various guises. Lower (than GlamourMag) impact factor journals sometimes try to upgrade by becoming more NS-like (Hi, J Neuro!). Meticulous science and exacting experimental designs are only respected (if at all) after the fact. Late(r) in someone's career they start getting props on their grant reviews for this. Early? Well the person hasn't yet shown the necessity and profit for the exhaustive designs and instead they just look...unproductive. Like they haven't really shown anything yet.
As we all know splashy CNS pubs on the CV trump a sustained area of contribution in lower journals six ways to Sunday. This is not to say that nobody will appreciate the meticulous approach, they will. Just to say that high IF journal pubs will trump. Always.
So the smart young PI is going to stay away from those messy sex-differences studies. Everything tells her she should. If he does dip a toe, he's more likely to pay a nasty career price.
This is why NIH efforts to promote sex-comparison studies are necessary. Promoting special funding opportunities are the only way to tip the equation even slightly more favorable to the sex-differences side. The lure of the RFA is enough to persuade the experienced PI to write in the female groups. To convince the new PI that she might just risk it this one time.
My suspicion is that it is not enough. Beyond the simple need to take a stepwise approach to the science as detailed by Isis, the career and funding pressures are irresistible forces.