Pain is complex, subjective, and influenced by many individual factors, including mood and thought patterns. This can make measurement feel difficult or even pointless at times, but pain assessment tools remain an essential part of effective pain management.
These tools help clinicians understand a patient’s pain more clearly and assess whether a treatment is working, whether that treatment is pharmaceutical, a device, or a physical or psychological therapy.
They are also a key part of combination and multidisciplinary care, where multiple approaches are used together and progress needs to be tracked over time. In clinical research, pain assessment tools are fundamental to evaluating new treatments in specific pain conditions.
There are several widely used tools to measure pain intensity in clinical practice and research.
The Visual Analogue Scale is a simple but widely validated tool. It consists of a 100mm line, usually anchored by descriptors such as “no pain” and “worst pain imaginable”.
Patients mark a point on the line that reflects their pain level. The score is then measured in millimetres from the starting point, providing a score out of 100.
The VAS is commonly used in clinical trials because it is sensitive and allows for fine-grained changes in pain intensity to be measured.
The Numerical Rating Scale is an 11-point scale where patients rate their pain from 0 to 10.
It is quick, simple, and can be used verbally in consultations or over the phone, making it one of the most commonly used clinical tools.
The Verbal Rating Scale uses a list of descriptive categories to represent pain intensity, such as:
no pain, mild, moderate, severe, very severe, worst possible pain.
While simple, some patients find it difficult to choose a single descriptor if their pain falls between categories.
Face-based pain scales use images of facial expressions to represent different levels of pain intensity.
These are particularly useful for children or patients who may have difficulty using numerical or verbal scales.
Common examples include the Wong-Baker FACES® Pain Rating Scale and the Faces Pain Scale – Revised. These tools must be explained carefully to avoid patients interpreting the faces as emotional states rather than pain levels.
Because pain is multidimensional, simple rating scales are often used alongside broader assessment tools.
The Brief Pain Inventory (BPI), for example, is a questionnaire that assesses multiple aspects of pain, including its location, severity, and impact on daily function. It also captures treatment effectiveness and how pain interferes with different areas of life.
Other commonly used tools include:
Pain cannot be measured in a purely objective way, which is why structured assessment tools are important. They provide a consistent way to track changes over time and help guide treatment decisions in both clinical practice and research settings.