How Does Self-Declared Chronic Pain Compare to Other Definitions? A Prospective Multicenter Study.

Background: Self-declared chronic pain has not been compared to existing definitions. Our objective was to evaluate the agreement between self-declared chronic pain and different chronic pain definitions, three months after an emergency department (ED) visit. Methods: In this planned substudy of a prospective multicenter cohort study, we included consecutive patients aged ≥ 18 years with an acute pain condition discharged from the ED with an opioid prescription. Three months after their ED visit, participants were asked about their pain intensity, pain frequency, pain disability, and self-declared chronic pain. Agreement between self-declared chronic pain and five other definitions were calculated with kappas. Results: A total of 1411 participants were included; mean age was 52 (±16) years, and 53% were female. Prevalence of self-declared chronic pain was 23.0% and varied from 16.9% to 45.3% for other definitions. Agreement of self-declared chronic pain was moderate (0.57-0.60) with most definitions but lower with the pain intensity ≥ 1 definition (0.47). The proportion of chronic pain participants using opioids ( ⁓20%) or other analgesics (⁓80%) was similar with all definitions except for the pain intensity ≥ 1 definition which was associated with a lower proportion of analgesic use (11%, 64%). Conclusion: In summary, self-declared chronic pain displayed moderate agreement with other chronic pain definitions and similar analgesic consumption but lower with the pain intensity ≥ 1 definition. Nonetheless, chronic pain prevalence varied greatly depending on how it was defined. Self-declared chronic pain might be a more patient-centered outcome and could be easily applied to standardize chronic pain definition. Trial Registration: ClinicalTrials.gov identifier: NCT03953534.