This has been bothering me for many years.

No, pain is not the 5th vital sign. It's not a sign at all.

Vital signs are the following: heart rate; blood pressure; respiratory rate; temperature.

What do those four signs have in common?

They can be measured.

A sign is defined as something that can be measured. On the other hand, pain is subjective. It can be felt by a patient. Despite efforts to quantify it with numbers and scales using smiley and frown faces, it is highly subjective. Pain is a symptom. Pain is not a vital sign, nor is it a disease.

How did pain come to be known as the 5th vital sign?

The concept originated in the VA hospital system in the late 1990s and became a Joint Commission standard in 2001. Pain was allegedly being under treated. Hospitals were forced to emphasize the assessment of pain for all patients on every shift with the (mistaken) idea that all pain must be closely monitored and treated .

This is based on the (mistaken) idea that pain medication is capable of rendering patients completely pain free. This has now become an expectation of many patients who are incredulous and disappointed when that expectation is not met.

Talk about unintended consequences. The emphasis on pain, pain, pain has resulted in the following.

Diseases have been discovered that have no signs and pain as the only symptom.

Pain management clinics have sprung up all over the place.

In 2010, 16,665 people died from opioid-related overdoses. That is a four-fold increase from 1999 when only 4,030 such deaths occurred. And the number of opioid prescriptions written has doubled from 109 million in 1998 to 219 million in 2011.

Meanwhile in the 10 years from 2000 to 2010, the population of the US increased by less than 10% from 281 million to 308 million.

Doctors are caught in the middle. If we don't alleviate pain, we are criticized. If we believe what patients tell us—that they are having uncontrolled severe pain—and we prescribe opioids, we can be sanctioned by a state medical board or even arrested and tried.

Some states now have websites where a doctor can search to see if a patient has been "doctor shopping." I once saw a patient with abdominal pain in an emergency room. After looking up her history on the drug use website, I noted that she had received 240 Vicodin tablets from various doctors in the four weeks preceding her visit.

That's a lot of Vicodin, not to mention a toxic amount of acetaminophen if she had taken them all herself.

What is the solution to this problem?

I don't know, but as long as pain is touted as the fifth vital sign, I do not see it getting any better.

Skeptical Scalpel is a recently retired surgeon and was a surgical department chairman and residency program director for many years. He is board-certified in general surgery and a surgical sub-specialty and has re-certified in both several times. For the last three years, he has been blogging at SkepticalScalpel.blogspot.com and tweeting as @SkepticScalpel. His blog averages over 900 page views per day, and he has over 6500 followers on Twitter.