GPDermDoc

The short story…it doesn’t.

The long story is that observational studies have a lot of bias.

These types of studies involve looking back and asking people about past behaviors, which can be difficult to remember (recall bias) and may be remembered differently depending on current conditions (observation bias). Subjects may also report or fail to report on other things that may impact the end observation point (confounding variables).

People who are sun exposed, sun sensitive, have a history of skin cancer tend to get more skin cancers.

They also tend to use more sunscreen.

So is the sunscreen causing the issue, or is it the sun exposure, propensity to burn and develop skin cancers?

In prospective trials, where one group has an intervention (like putting sunscreen on daily) and the other group does not (only uses sunscreen when they want) and then those two groups are followed for some time (usually years), the sunscreen applying group clearly shows benefit (less cancers and less photo damage/wrinkling).

This design helps to establish a more clear cause and effect relationship, rather than a mere correlation which we can see in retrospective/observational study (especially one that relies on a subject’s memory and doesn’t control for other variables).

The take home point here?

People lie using statistics to suit their goals.

It can go both ways but unfortunately it seems common among the wellness-grifter types.

If you hear something that seems like a paradigm shifting conclusion, please press pause.

Listen to input from scientists (btw your dermatologist is a physician, we are scientists).

We often look for results to be reproduced multiple times and with different study designs. This safeguards against bias and other unanticipated anomalies.

I’ll link an article that shows why the “conclusion” some are drawing from that UK study is not the whole story, and another link to a creator who explains this really well in my stories.

Stay cool out there! 🥵