Chronic pain in Australia: a prevalence study :

This research develops and evaluates a simple method of grading the severity of chronic pain for use in general population surveys and studies of primary care pain patients. Measures of pain intensity, disability, persistence and recency of onset were tested for their ability to grade chronic pain severity in a longitudinal study of primary care back pain (n = 1213), headache (n = 779) and temporomandibular disorder pain (n = 397) patients. A Guttman scale analysis showed that pain intensity and disability measures formed a reliable hierarchical scale. Pain intensity measures appeared to scale the lower range of global severity while disability measures appeared to scale the upper range of global severity. Recency of onset and days in pain in the prior 6 months did not scale with pain intensity or disability. Using simple scoring rules, pain severity was graded into 4 hierarchical classes: Grade I, low disability--low intensity; Grade II, low disability--high intensity; Grade III, high disability--moderately limiting; and Grade IV, high disability--severely limiting. For each pain site, Chronic Pain Grade measured at baseline showed a highly statistically significant and monotonically increasing relationship with unemployment rate, pain-related functional limitations, depression, fair to poor self-rated health, frequent use of opioid analgesics, and frequent pain-related doctor visits both at baseline and at 1-year follow-up. Days in Pain was related to these variables, but not as strongly as Chronic Pain Grade. Recent onset cases (first onset within the prior 3 months) did not show differences in psychological and behavioral dysfunction when compared to persons with less recent onset. Using longitudinal data from a population-based study (n = 803), Chronic Pain Grade at baseline predicted the presence of pain in the prior 2 weeks. Chronic Pain Grade and pain-related functional limitations at 3-year follow-up. Grading chronic pain as a function of pain intensity and pain-related disability may be useful when a brief ordinal measure of global pain severity is required. Pain persistence, measured by days in pain in a fixed time period, provides useful additional information.

In this review epidemiological studies concerning chronic benign pain among adults are discussed. To this end, studies focusing on chronic pain, reporting prevalences at a population or primary health care level, including subjects aged between 18 and 75 years have been collected and analyzed. Focus of analysis was on research methods, definitions of chronic benign pain used, and reported prevalences. Prevalences varied between 2% and 40% of the population. Nor method used (telephone survey, postal survey, nor definition of chronicity (>1 month; >3 months; >6 months) clearly explained the differences in prevalence in the various studies. Implications for future research are discussed.

In epidemiologic research on chronic pain, differentiation of recurrent, persistent and disabling pain states is critical in the investigation of burden, natural history, effective intervention and causal processes. We report population-based data concerning the development and evaluation of a graded classification of pain status. In a probability sample of 1016 health maintenance organization enrollees, recurrent or persistent pain was observed in 45%; severe and persistent pain in 8%; severe and persistent pain with 7 or more days of pain-related activity limitation in 2.7%; and severe, persistent pain with activity limitation and 3 or more indicators of pain dysfunction in 1.0% of the population sample. Graded chronic pain status was associated with psychological impairment, unfavorable appraisal of health status, and frequency of use of pain medications and health care. The presence of severe and persistent pain increased the likelihood of multiple indicators of pain dysfunction, but there was considerable heterogeneity in pain dysfunction among persons with comparable pain experience. Our data suggest grading chronic pain in terms of 3 axes: time (persistence); severity; and impact (disability and dysfunctional illness behaviors).