Women have a higher risk of DCS! – Seriously?

A recent analysis of the DAN database has yielded a surprising result: women appear to have a significantly higher risk of decompression illness (DCI) than men. The analysis is based on nearly 128,000 dives by approximately 5,900 divers. Overall, DCI was reported in about 0.49% of dives. In the data, DCI occurred about three times more frequently in women than in men; statistical modeling even yielded an odds ratio of 4.63—a more than fourfold higher risk for women! How is this possible?

Agincourt reef, Australia

First, the study demonstrates very convincingly what one would expect anyway: The most important factor influencing the risk of DCI is the actual supersaturation upon ascent, expressed as the so-called Surface Supersaturation Gradient (DSSG). Other factors also fit well into the established picture: short surface intervals, multiple gases as an indicator of deeper and more demanding dives, physical exertion, or technical dives increase the risk. Ultimately, all of this reflects one thing: higher exposure and greater stress are associated with a higher risk of DCI.

The observed gender difference, however, raises fundamental questions. While the authors discuss possible biological differences between the sexes—such as differences in the inflammatory and coagulation systems, hormonal effects, or differences in bubble physiology—this remains speculative. And this is precisely where it is worth taking a step back.

DCI is not a random event, but is strongly dependent on behavior.

After all, decompression sickness is not a random occurrence, but is heavily dependent on behavior. Depth, duration, conservative planning, and discipline during ascent are ultimately conscious decisions. And this is precisely where a contradiction arises: It is well documented that women exhibit less risky behavior than men—whether in traffic, in extreme sports, or in financial decisions, to name just a few areas of life that have been well studied. Why should the opposite be true specifically for decompression illness, which is highly behavior-dependent?

First, one should be aware of the fundamental methodological limitations of such registry data: These are non-blinded observational data, in which neither diagnoses nor exposures are consistently standardized or independently verified, and numerous influencing factors remain uncontrolled. Such data are very valuable for identifying patterns and generating hypotheses—but they do not provide proof. A statistical association should therefore not be hastily interpreted as a causal relationship, especially when plausible alternative explanations exist.

Women take fewer risks than men.

I suspect that a possible explanation lies in the data collection process itself. The underlying data is based on self-reporting—that is, on what divers themselves report. And this is where a systematic bias could arise. It is well known that men are more likely to downplay health issues, report symptoms later, and are generally more reluctant to admit to medical complaints. A diagnosis such as decompression sickness, in particular, implies that something did not go as planned—be it in terms of planning, behavior, or assessment. It is therefore not far-fetched to assume that divers are more likely to ignore mild symptoms or fail to report them, or even admit them to themselves.

Men are more likely than women to downplay symptoms.

Conversely, it is well known that women report symptoms in greater detail and often notice physical changes earlier. This would mean that they are more likely to report or notice decompression sickness.

Statistical differences do not automatically equate to biological differences. If part of the observed difference stems from reporting behavior, a risk appears higher than it actually is. In this light, the finding of a supposedly significantly increased risk of DCI in women appears, at the very least, open to debate.

My personal impression is therefore: The study provides valuable insights into known risk factors such as supersaturation, stress, or complex dive profiles and underscores their importance. The gender difference, however, should be interpreted with caution. For association is not synonymous with causality. Before postulating biological causes, one should, for example, rule out the possibility that reporting simply differs.

Or, to put it another way: Perhaps women do not actually have a higher risk of decompression sickness. Perhaps men simply report their problems less frequently.

This is also in line with the current literature, which lacks consistent scientific evidence that women generally have a higher risk of DCS than men.