Evaluation of Pain Characteristics & Intensity

Acute vs. Persistent Pain

The distinction between acute and persistent pain (Table: Differences Between Acute and Persistent Pain) is particularly relevant. Acute pain characteristically is of recent onset and is anticipated to have a relatively short duration of no more than days or weeks. Pain is usually considered persistent if it persists more than 3 to 6 months. Management strategies become significantly altered once pain becomes persistent and initiating timely pain management interventions is essential. For this reason, a number of experts also define persistent pain as 1) pain persisting for at least one month beyond the usual course of an acute illness or the time required for an injury to heal, 2) pain associated with a chronic pathologic process, or 3) pain recurring at intervals of months or years.

Nearly all patients with progressive diseases, such as cancer and AIDS, experience repeated episodes of acute pain which may be related to the disease, therapeutic interventions, or unrelated processes. In patients with persistent pain, intermittent episodes of acute pain may occur spontaneously or in association with a particular activity, and are referred to as breakthrough pain. Almost two-thirds of cancer patients with persistent pain report breakthrough pain. Given their frequency, breakthrough pain and other types of acute pain should be specifically assessed during the evaluation of persistent pain. A daily pattern of varying pain intensity may exist and diurnal variations are found in some painful conditions such as arthritis (i.e., pain worse in the morning).

The terms acute, persistent, and recurrent pain can be used to depict a wide variety of pain syndromes. Acute monophasic pain is usually of brief duration and is expected to resolve as the underlying cause resolves over hours, days, weeks, or months. When the acute pain is recurrent at relatively brief intervals, the impact can mirror persistent pain. Recurrent pains of this type may be reported by patients with headaches, dysmenorrhea, sickle cell anemia, inflammatory bowel disease, arthritis or musculoskeletal disorders. Pain that is present most of the time, typically fluctuating but seldom absent, comprises a broad clinical group, including persistent pain associated with cancer, nonmalignant progressive disease (e.g., AIDS, sickle cell anemia, hemophilia, and connective tissue diseases), nonprogressive or slowly progressive diseases (e.g., severe osteoporosis, postherpetic neuralgia, painful polyneuropathy, reflex sympathetic dystrophy), and idiopathic syndromes (e.g., fibromyalgia, atypical facial pain, chronic pelvic pain of unknown etiology).