[Pain intensity scales and assessment of cancer pain].

The ability to assess pain intensity is essential for both clinical trials and effective cancer pain management, although cancer pain assessment is complicated by a number of other bodily and mental symptoms such as fatigue and depression, all affecting quality of life. Several pain assessment tools have been shown to be reliable and reasonably valid in assessing cancer pain. Pain intensity scales are classified as self-report or observational and unidimensional or multidimensional. They include the numeric rating scales (e. g., 0 to 10), visual analogue scales (e. g., a 10-cm line with anchors such as "no pain" on the left and "severe pain" on the right; the patient indicates the place on the line that best represents the intensity of pain) or a verbal descriptor scales (e. g., "no pain", "mild pain", "moderate pain", "severe pain"). A variety of scales use drawings of faces (from smiling to distressed) for children or patients with cognitive impairment or dementia. The healthcare providers should use tools valid for the patient's age and cognitive abilities, with additional attention to the language needs of the patient.