Vital signs are vital: Pain

The following is one in a series of columns by guest authors illustrating the importance of vital signs to the practice of hospital medicine.

Pain can have drastically different meanings, from a 6 out of 10 while under the fluorescent lights in the post-anesthesia care unit to a 600 out of 10 while mourning heartbreak and cuddling a pint of Ben and Jerry's. Pain is subjective and intensely personal and can only be truly understood by the person suffering. However, by declaring pain a vital sign, medicine has attempted to make pain an objective, measurable data point (1).

Pondering pain is an ancient pastime. Aristotle viewed pain as a matter of the soul, an emotional experience rather than a sensory one. Pain was not one of the “senses.” Instead, it was a condition arising outside of the body and cast upon the suffering. Hippocrates recognized the diagnostic value of pain and used it as a warning sign of an underlying disease process. This concept, first explored in medical texts written in the fourth century B.C., has held up to the test of time.

In ancient religious texts, pain and suffering are described as necessary parts of life. In the Bhagavad Gita, a sacred Hindu text, life is equated with pain. The Four Noble Truths of the Buddhist faith detail “dukkha” or suffering as part of the framework for understanding life and Buddhist ideology. The Christian view of salvation depends on Christ's pain and crucifixion. Christians have historically viewed pain and suffering as an opportunity to more fully understand God.

Since the dawn of the scientific revolution, several theories for understanding the physiologic mechanism of pain perception have been proposed. Our modern understanding of pain is based on the molecular makeup of neurons, the signals traveling through specialized sensory fibers through the thalamus and into the cortex. As understanding of pain has shifted to neural pathways, effective methods for controlling pain have been devised, from the prehistoric discovery of opium to the introduction of surgical anesthesia in 1846. In the era of modern medicine, our arsenal is filled with drugs that dull and relieve pain.

Our current understanding, however, has not protected patients from experiencing pain or practitioners from misunderstanding it. In the early 1990s, it was determined that clinicians were not meeting their patients' needs for pain control, often because they failed to assess pain or reassess after treatment (2). In response, the American Pain Society introduced the concept of the “fifth vital sign” in 1996. In his presidential address to the society that year, James Campbell, MD, said, “Vital signs are taken seriously. If pain were assessed with the same zeal as other vital signs are, it would have a much better chance of being treated properly. We need to train doctors and nurses to treat pain as a vital sign. Quality care means that pain is measured and treated” (3).

A few years later, the Veterans Health Administration implemented a comprehensive national strategy for pain management, which entailed routine screening for pain with the numeric rating scale and required documentation (4). The Joint Commission has set standards for all health care facilities requiring clinicians to recognize, assess, and treat pain with safe and effective management plans. These standards encourage the incorporation of pain assessment as a regular part of the physical exam.

The most common pain assessment tool is the numeric rating scale on which a patient rates his or her pain between 0 and 10. Another is a verbal scale on which patients choose among no pain, mild pain, moderate pain, severe pain, or unbearable pain. Multidimensional pain assessment tools have also been developed for chronic pain. Some are general tools that have been validated for cancer and noncancer pain. Others are specific to the cause of pain, such as the Neuropathic Pain Scale, S-LANSS, and DN4. Many versions of “faces scales” have also been developed to make pain scales accessible to everyone, regardless of literacy or language.

Despite these efforts, many Americans continue to suffer—over 100 million were in chronic pain according to a 2011 estimate. Beyond the intense toll this takes on individuals and their friends and family, pain is also an economic burden, estimated at $635 billion dollars annually in treatment cost and lost productivity (5). We clearly have significant strides to make in the realm of pain control.

Given the long history of pain and the human fascination with describing and understanding it, it is no wonder that alleviating pain has been and remains a primary goal of medicine.