Gold mine or dumpster dive? A closer look at adverse event reports

Correlation doesn't always equal causation

All informed health decisions are based on an evaluation of risks and benefits. Nothing is without risk. Drugs can provide an enormous benefit, but they all have the potential to harm. Whether it’s to guide therapy choices or to ensure patients are aware of the risks of their prescription drugs, I spend a lot of time discussing the potential negative consequences of treatments. It’s part of my dialogue with consumers: You cannot have an effect without the possibility of an adverse effect. And even when used in a science-based way, there is always the possibility of a drug causing either predictable or idiosyncratic harm.

An “adverse event” is an undesirable outcome related to the provision of healthcare. It may be a natural consequence of the underlying illness, or it could be related to a treatment provided. The use of the term “event” is deliberate, as it does not imply a cause: it is simply associated with an intervention. The term “adverse reaction,” or more specifically “adverse drug reaction,” is used where a causal relationship is strongly suspected. Not all adverse events can be be causally linked to health interventions. Consequently, many adverse events associated with drug treatments can only be considered “suspected” adverse drug reactions until more information emerges to suggest the relationship is likely to be true.

Correlation fallacies can be hard to identify, even for health professionals. You take a drug (or, say, are given a vaccine). Soon after, some event occurs. Was the event caused by the treatment? It’s one of the most common questions I receive: “Does drug ‘X’ cause reaction ‘Y’?” We know correlation doesn’t equal causation. But we can do better than dismissing the relationship as anecdotal, as it could be real. Consider an adverse event that is a believed to be related to drug therapy: Continue reading

The risks of CAM: How much do we know?

Working in pharmacies where supplements are sold alongside traditional (over-the-counter) medications, I’m regularly astonished at the different perceptions consumers can have about the relative efficacy and safety of different types of products. Once, speaking with a customer about a medical condition she wanted to treat, I indicated that there were no effective non-prescription therapies — she needed to see a physician for access to an effective treatment by prescription — and I gestured behind the counter. “Back there?!” she pointed. “That’s where you keep the stuff that kills people! I want something natural!” Suggesting that my patients with heart disease or HIV had a somewhat different perspective, I tried (unsuccessfully) to talk her out of a questionable-looking supplement (Hint: avoid anything from a company with a P.O. box as a mailing address.) This appeal to nature, combined with a perception that natural products are safe, and conventional drugs are unsafe, is pervasive. Continue reading