You probably know someone who seems to have a high pain tolerance — brushing off injuries like they’re nothing. You might also know people who get teary after they stub their toe.
That’s because everyone experiences pain differently.
Unfortunately, there’s no definitive lab test or x-ray-like machine that can measure pain. Instead, health care providers rely on the person in pain to describe how it feels. But describing pain is difficult. Everything people say about pain is subjective. They might say the pain is severe, but “severe” means something different to everyone.
To try to make pain assessment easier and more accurate, clinicians created pain scales. Pain scales can be a valuable tool, but when used by themselves, pain scales don’t always work as intended.
What’s a pain scale?
Pain scales are communication tools used to assess the amount of pain a person is experiencing. If you’ve had an injury or surgery, you’ve likely been asked something like, “On a scale of zero to 10 — with zero being no pain and 10 being that guy who got eaten in ‘Jurassic Park’ — how would you rate your pain?” That’s a pain scale.
There are several kinds of pain scale assessments. They vary by focus (e.g., pain intensity, pain-related experiences, pain duration) and format (e.g., single question, multi-page questionnaire, graphics or charts). Clinicians use different scales based on the situation, the individual and type of pain.
Here are a few examples of commonly used pain scales.
The Numeric Pain Intensity Scale (NPIS)/Visual Analog Scale (VAS)
The “Jurassic Park” example above is an example of the NPIS or VAS. It asks people to rate their pain intensity on a numbered scale — with zero as no pain and 10 as the worst pain imaginable.
The Faces Pain Scale
The Faces Pain Scale is similar to the NPIS, but it provides depictions of faces in pain. Like the NPIS, it asks the individual to choose a face that shows “how much it hurts.” It was originally designed to help children, aged 3 and older, communicate about their pain, but it’s often used for people of any age.
PEG-3: Pain screening tool
The Pain, Enjoyment of life and General activity (PEG) scale is a three-question assessment used for monitoring pain over time. In each question, individuals are asked to score their pain based on a 0 to 10 scale (similar to the NPIS). The assessment was designed to learn more about how pain is affecting the person’s life. The questions are:
- What number best describes your pain on average in the past week? (0 = no pain, 10 = pain as bad as you can imagine)
- What number best describes how, during the past week, pain has interfered with your enjoyment of life? (0 = does not interfere, 10 = unable to carry on any activities)
- What number best describes how, during the past week, pain has interfered with your general activity? (0 = does not interfere, 10 = completely interferes)
McGill Pain Questionnaire (MPQ)
With the MPQ, the people receiving care are given a worksheet, or instructed to use an online app, that lists 78 words associated with pain. They’re asked to choose the words that best describe their pain such as stabbing, intense, itchy, tender or tight. The health care provider then uses a scoring system to evaluate the person’s pain. Since it was created in 1975, the MPQ has been proven to be a valid measurement of pain in studies focused on various types of pain, from cancer to musculoskeletal shoulder pain.
The advantages of pain scales in pain assessment
Pain scales help clinicians understand a specific person’s pain journey and create a treatment plan. Simple pain scales, like the NPIS, provide basic information. Complex pain assessments, like the MPQ, provide more context. They both streamline communication between providers and the people they treat.
Pain scales have other benefits. For example, they:
- Are quick and easy to use. As the Faces Pain Scale shows, even a 3-year-old can understand how to communicate their current pain intensity. Additionally, simple pain scales like the Face Pain Scare or the NPIS require little equipment or training.
- Help track pain over time. When a pain scale is used consistently over time, it can help determine whether a person’s pain is getting better or worse.
- Inform treatment plans. A pain scale can also help providers gauge whether a therapy is working for a specific individual. For example, if a person takes the PEG-3 assessment three days in a row and switches medication on the second day, a lower pain score on the third day might suggest the new medication is working better than the previous one.
The disadvantages of pain scales in pain assessment
Although pain scales are useful tools, they need to be paired with more objective information to create effective treatment plans. Most issues with pain scales happen when they are used as the only or primary source of information about a person’s pain.
Pain scales are subjective
Pain scales give providers valuable — but subjective — information. For example, some people can rank their pain at an 8 out of 10 and still go to work, while others can’t get out of bed with a score of 3. One study showed that even asking a follow-up question such as “Is your pain tolerable?” adds critical information for the provider and helps align someone’s expectations with realistic treatment goals.
Pain scales provide a limited view of the pain experience
Many pain scales focus on a person’s pain level at the moment of the test and fail to address how pain affects people’s daily life. For example, pain scales often don’t accurately assess:
- Pain tolerance. Every individual’s tolerance to pain is unique. It’s shaped by biological and psychological factors — including genetics.
- Pain history. An account of previous or ongoing pain can inform how a person copes with pain and what treatments have worked in the past.
- Emotional state. Emotions can influence a person’s pain scale ratings. In addition to pain, people often feel anxiety, anger, grief, stress and helplessness.
- Pain changes with activity. Pain may get better during certain activities and get worse with others. For example, a person with chronic back pain could feel worse after sitting at a desk all day and better after a yoga class.
- Pain fluctuations over time. Many pain assessments only reflect how much pain the person is feeling at the time of the test. It can increase or decrease with the time of day. Recent studies suggest it’s more valuable to ask individuals to rate their average pain over a week or more.
Numeric pain scales can be particularly problematic
Numeric pain scales, like the NPIS, are often criticized because it’s hard to interpret what a number means to each person. Additionally, one study showed that continually asking people to rate their pain on a scale of zero to 10 implies that being 100% pain-free is an attainable treatment goal. This might lead to unrealistic expectations for a complete recovery.
Overusing pain scales can delay long-term outcomes
Most clinicians want to help people heal from an injury or — in the case of chronic pain — learn to manage the pain over the long term. But when providers place too much emphasis on a pain scale, the primary goal can become reducing short-term pain intensity instead of long-term pain management. Consequently, keeping pain scores low with medication can be a barrier to getting people back to their regular routines. Many experts believe that providing education about active pain treatments, such as relaxation techniques and mindfulness practices, can help people manage pain more effectively over time.
People sometimes equate pain scale scores with care quality
People often tie satisfaction during care (such as hospitalization or therapy) to their experiences with pain. They equate pain scale scores with the quality of care. In the 1990s, pain scale results became linked to national hospital and provider ratings which impacted their government funding. This led to pressure to prescribe opioids instead of other treatments. While pain scales aren’t as clearly linked to hospital ratings today, they can still be a prominent factor influencing how an individual experiences care.
How pain scales are used in pain assessment today
Today’s providers are transitioning away from using only pain scores and descriptors to monitor pain and treatment success. Instead, they strive to assess the person, not just the number. They ask people who are experiencing pain about what’s important to them. Is it being able to go to work? Being present for your kids? Playing basketball again? Answering questions about their goals is more powerful than a number or survey result. This profound change in thinking puts the person — not the pain — at the center of the discussion.
Some passages in this text appear in the Mayo Clinic Press Book “Ending the Crisis: Mayo Clinic’s Guide to Opioid Addiction and Safe Opioid Use.
Relevant reading
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